ESE's works engine tuner

[husaberg]

Good, I plan on stealing it. I mean, would you like your basement cleaned?:shifty:
Stealing seems little harsh. For most of the accounts suggest a lot of the MZ technology had been "Nationalised" as it was in the first place.
Degner just disseminated it. For us all to share. Well eventually anyway.

Who knows for sure, what actually went down, I wasn't there anyway. Maybe those Suzuki's and Yamaha's getting so fast so quickly... was just a coincidence.:innocent:
But ones things for sure. The Japanese had far greater metallurgical technology and immense financial resources.

[TZ350]

Ok not a new single port but the old triple port re-jigged (as best I can) in EngMod2T to work with Wobblys pipe.

Now you didn't know you could get so much port and blow down area into an original 78 Suzuki GP125 cylinder.

Maybe next week we will get it onto the dyno, then see if this sucker eats pistons too and whats needed to cure it of the habit.

[dinamik2t]

Hey TZ, cylinder looks tidy!
Tell us about port durations in this cylinder in comparisson with the single-Ex one - unless there are any japanese cameras around :shifty:

By the way -ie: me liking the port radiuses in your cylinder- I found this tooling : http://www.ebay.co.uk/itm/260998568874?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649#ht_1681wt_1270

A radius gauge. There are also available in the 1-6, 15-20something and 26-80 mm range. It's a little 'gadgetty' :D - I got a pair for port radius measurement.

[Frits Overmars]

Find the radius gauges...

[dinamik2t]

Many thanks to Frits from my part also!

Except all other impressive stuff in the files, there is some that tingled my curiosity.
It's in the last two photos of the 5th folder, named "workbench". What are those circular stuff on the wooden rectangle, between the pipes and the cylinders?? Remind me of those mirrors the dentists use.:sweatdrop
(8th December 2011, 11:39)



Better late than ever :drinknsin -ha! How was your trip to Germany, Frits?

[Yow Ling]

Frits, Could this be an answer to the sliding seal on your friends 50

http://www.circlecycleice.com/page9.php

go to the images page and look at the compression rings. The engine is a bit erotic and out there but may have something there for us

[TZ350]

Hey TZ, cylinder looks tidy!
Tell us about port durations in this cylinder in comparisson with the single-Ex one -

The single Ex port opened 78.5 deg ATDC @ 75% the tripple was going to be 85 but now its 82 @ 73%. The transfers are the same at 116-117-117, Inlet 145/85.

[Yow Ling]

http://www.epi-eng.com/piston_engine_technology/comparison_of_cup_to_f1.htm

http://www.epi-eng.com/piston_engine_technology/engine_technology_contents.htm

[breezy]

can anyone shed any light on whats going on here. i run the piston back to front to avoid the piston ring ends falling in the in the inlet port.with what ive seen previously in other forums is that its running to lean and over heating, although the plug showed it to be running rich. it did tighten up momentarily and cut out but did run again after about 15mins in the pits. having just pulled it apart i can see that i have some issues.any feed back would be very helpfull.. thanks

[TZ350]

Lots of interesting stuff there. Like running the piston back to front. I guess the ring ends travel on the portion of barrel between the transfers and exhaust port. How wide is the exhaust port? and it looks like its running an iron cylinder, BSA Bantam? also interesting combustion chamber shape too.

The motor does look like it has got hot.

Assuming you have the mixture and ignition timing correct and no air leaks then my money is on the inside diameter of the stinger (or stinger venturi) being to small, makes good power on the dyno but eventually over heats the motor and the piston crown in particular. How does the stinger size compare to other similarly setup engines.

Hopefully, some of the (more knowledgable than me) developers on here will post their ideas too.

[crazy man]

262360262361how much would you pay for this bit of rubbish? gt50

[worm13]

ummm would a marriage do?? other then that I think your asking to much!!

[TZ350]

I have been looking at the Trombone pipe again and can see that its best used for extending over rev. So I need a pipe that makes good power at 9,000 rpm with an exhaust opening at 82 deg ATDC and then by shortining the trombone I can keep the system in resonance for a good 4k maybe even 6 at a stretch.

The down side is the plenum which adds a usefull bit of top end but only works over a limited range, good for a conventional pipe but detracts from a Trombone style pipe as the plenum only works well in one place then reduces the power elsewhere.


If you take the sim as I last ran it then do a Turbulent Model with your ignition curve,the TuMax will be thru the roof,and the program will probably scream DETO WARNING at you in the mis range.

262387

The EngMod det warning that would have told me that I was in dangerus teritory on my earlier engine.

[husaberg]

262360262361how much would you pay for this bit of rubbish? gt50

I sat my learners on a GT50, Mag wheels and a disk brake It was a mates but i still thought it was bitchen. :shit:
But where they air cooled or water cooled?

[2T Institute]

A nice pic of the latter Roberts Proton V3 cylinders (the one that started to go well before the 2002 4T change :facepalm:) Spool PV's with a ATAC chamber. Looks as though they had experiments with volumes to.

[crazy man]

I sat my learners on a GT50, Mag wheels and a disk brake It was a mates but i still thought it was bitchen. :shit:
But where they air cooled or water cooled?was air cooled now water . this one has the nz land speed record for a 50

[worm13]

was air cooled now water . this one has the nz land speed record for a 50

Who bulit that awesome machine!! hahaha I know where there are photos of it when it had set the record and there was also a matching sidecar outfit to boot!

[crazy man]

Who bulit that awesome machine!! hahaha I know where there are photos of it when it had set the record and there was also a matching sidecar outfit to boot!better post

[worm13]

better post

Yup will do, give me a couple of days to sort it all out and il post them! bike looked pretty cool way way way back in the day!

[speedpro]

I could never beat Pete on that bike but my AC50 was fast enough to keep him honest and he fell off at Whakatane and removed a bit of flesh keeping in front. I think him and Ram turned up in a van full of buckets with a sidecar tied to the roof on the inside to that meeting.

[jasonu]

A nice pic of the latter Roberts Proton V3 cylinders (the one that started to go well before the 2002 4T change :facepalm:) Spool PV's with a ATAC chamber. Looks as though they had experiments with volumes to.

Mate I don't remember any of the Roberts Protons doing well at any time.

[TZ350]

These graphs were drawn using kW's so that the curves might more visualy represent the real DIN or PS hp I might see from the back wheel on the dyno.

262417

I have been looking at the Darcy RG500 pipe that peaks at 10,500 and simulating it with a Trombone header. By shortining the header 130mm It looks like I can get the power spread to extend out to 14K.

It might be down a little on power but the total amount of power under the curve is much greater than I had before.

262438

This is the same Darcy pipe and Trombone header simulated with a 2L Plenum, the combination bumps it into the low 30's.

[husaberg]

Mate I don't remember any of the Roberts Protons doing well at any time.

Jeremy McWilliams put one on pole once,can't remember where. So it must have gone well at least that day.
He would have looked a bit younger than this though.
http://r28.imgfast.net/users/2813/47/10/07/album/proton10.jpg
http://r28.imgfast.net/users/2813/47/10/07/album/proton11.jpghttp://newsimg.bbc.co.uk/media/images/42583000/jpg/_42583501_mcwilliams203.jpg

[TZ350]

EngMod2T

262439

I remember there was a bit of a discussion about whether the expansion chamber supercharged the engine when it is in resonance.

Well at a delivery ratio of 1.4, the pipe must be doing something.

[2T Institute]

Mate I don't remember any of the Roberts Protons doing well at any time.

Jurgen van de Goorbergh finished 13th in the championship in 2001 (looks like the team sat out 4 or 5 GP's) finished best of 7th and worst 13th. Up against 4 factory NSR500's and 6 factory YZR500's and 2 factory RGV500's with the best riders the factories could afford on a self built bike with a rider they could afford, is pretty good in my books.

[dinamik2t]

The single Ex port opened 78.5 deg ATDC @ 75% the tripple was going to be 85 but now its 82 @ 73%. The transfers are the same at 116-117-117, Inlet 145/85.

Nice!
In the tripple ex setup, perhaps you should rise the TFRs a little more.
And on a side note: in the sim, I always see a drop in power when Aux. Exs are at the same opening height as the main. I believe it's best to 'retard' them about 3-5 degrees.
RSA's auxiliaries must open after the main too - at least I reckon so from the photos. Frits or Wob could enlighten us when they have time.

[breezy]

Lots of interesting stuff there. Like running the piston back to front. I guess the ring ends travel on the portion of barrel between the transfers and exhaust port. How wide is the exhaust port? and it looks like its running an iron cylinder, BSA Bantam? also interesting combustion chamber shape too.

The motor does look like it has got hot.

Assuming you have the mixture and ignition timing correct and no air leaks then my money is on the inside diameter of the stinger (or stinger venturi) being to small, makes good power on the dyno but eventually over heats the motor and the piston crown in particular. How does the stinger size compare to other similarly setup engines.

Hopefully, some of the (more knowledgable than me) developers on here will post their ideas too.

heres a port map and exhaust diamentions and cylinder head insert. the ignition ducati energiser( kart ignition) mikuni 34mm flatslide. i did a leak test before pulling it a part at 6psi for 6mins and it was fine.i think the problem has been poor carb set up and probably ignition. the b10es plugs oiled up quickly at low revs looked to be slighty rich on inspection after a unexpected plug chop oppertunity!262447262448262449

[TZ350]

An Email from Av's Dad.

Hi everyone, for those I haven't caught up with recently Avalon is
racing in Italy over the next six months in a five round Honda 600
series. This all came together very quickly and she left NZ asap to get
to a test day there. We have recently organised for her to also race the
same bike in the Italian Womens Championship to give her more track time
there.

WILsport management have come on board to assist us in making this
happen and a link to her latest report is below

http://wilsportsmanagement.com/latestnews.htm


Cheers
Keith

[TZ350]

How about a variable exhaust header. This one allows 25mm adjustment

241299
241300

Google translate says "a new control to include inflammation of RTD and the like" Thanks Google.

Kel reminded me of where he had posted pictures of a variable exhaust header.

[husaberg]

Kel reminded me of where he had posted pictures of a variable exhaust header.

Frits used the same example.

Bimota did that once: they built a pressurized thin-wall tubular frame with a manometer, so you could scientifically establish when the frame had developed a crack.
Added rigidity: sure. Maybe not so that you'd notice, but it certainly won't hurt. I once filled most cavities in my car with expanding building foam. It made the car feel twice as stiff!
Going electric on the movable pipes is not too bad either. I was talking about a Yam TZ500 four cylinder sidecar engine, but for a single the electricity consumption will not be all that much. Here are some pictures to wet your appetite:
249693249703249694


It would certainly help with useful overrev on tight tracks as well as when you have a wide ratio gearbox


Variable pipe lengths with length or temps


You have to stay within certain length percentage limits for all elements of the exhaust system; you cannot make one part a lot longer or shorter in relation to the others without losing power somewhere.
It is best to concentrate on getting all dimensions correct for maximum power. In the high gears you don't ride low revs and in the low gears you'll have enough low-down power left to pull a wheelie or spin out the rear wheel (I'm not talking about buckets though, so you might want to reconsider your case).
If you have a decent setup for angle*areas, pipe, carburation and ignition, the necessary overrev potential will come naturally; no need to sacrifice maximum power in order to make it rev a little higher.



Re adjustable pipes
I know Cagiva ran a Hydraulic system and I think electric is to slow and to thirsty for power.
I also know that Cagiva ran the power valve (YAMAHA Style I guess) and Atac valve on the Randy Mamola bike.

249692

I planed at a later stage to use a Greeves (woolley) style labryrinth seals with piston rings to seal the pipes.

My idea was compressed air. Easily rechargeable light nice and simple, super fast and a little goes along way.
I planed to run the Water injection the same way and use excess air in the pipes to reheat it them.
maybe a little fuel if there wasn't enough in the pipes to work it what do you think. I also envisaged using air/electric to trigger the Atac


Bimota did that once: they built a pressurized thin-wall tubular frame with a manometer, so you could scientifically establish when the frame had developed a crack.
Going electric on the movable pipes is not too bad either. I was talking about a Yam TZ500 four cylinder sidecar engine, but for a single the electricity consumption will not be all that much. Here are some pictures to wet your appetite:
249693249703249694

How about a variable exhaust header. This one allows 25mm adjustment

241299
241300

Google translate says "a new control to include inflammation of RTD and the like" Thanks Google.


Compressed air is rechargeable and simple. I am not so sure about 'light and going a long way'. You might want to do a rough calculation on how much volume at what pressure you consume each time the pipe is moved. That could force you to use a bigger air bottle than you had planned...
A CO2-cartridge could be your way out: I estimate its energy density to be about a hundredfold better than air. Or, what I would do in Holland: use LPG (liquified petroleum gas, or autogas). I don't know whether you guys use the stuff in NZ, but I can get it at every street corner; the pressure is about 8 bar and being liquid its energy density (just talking about the pressure, not about what happens when you light it) is much better than that of compressed air.





Saving that for pulling the slippery pipe.

Frits Overmars

A powervalve does not really give you real resonance power; it just prevents the pipe pulses from completely messing up the power curve at low revs. I expect a sliding pipe will make more low-down power.

http://www.pit-lane.biz/t1666p15-technique-rossigrm-2strokes-boat-engine?highlight=twin+rotary



If you are using an Ignitech then by adding an RZ or R1 powervalve servo means you can program any position you like into a moving slide or rotary "timing changer" - easy.
Having a movable "slide" in behind the closing edge of a rotary valve, pushed/pulled into position by servo cables, would be easy and reliable. Get on with it.


I was just pointing out that the idea of using water, great as it may be in theory, and on a dyno when looking for bottom end, it "works" just fine.
But in a controlled test to see if its was useful, it failed, as the systems effect had to be reduced so much that any gain in bottom end was still offset by a loss in the top end.
As Burgess said, when the effect was useful, it took too long to reheat the pipes.
My thoughts, from the testing I did with a PV and ATAC operated separately ( instead of combined together as many MX engines have now) is that this works real well with no down sides at all,and is easy to implement.



OK, here is some info on how to utilise the servo option on the Ignitech.
The servo has 5 wires, two are 12V +/- and the other 3 are the servo feedback positioning pot.
Always wire the two functions on separate plugs. Once you have the servo connected to the blade or whatever, disconnect the servo motor power plug.
Then on the screen you will have a readout for the servo position, as mV or as a % if using the RACE box.
I have never used the % option so here is how to program the mV setup. Drive the servo to the travel limit ( in, or down or whatever) by gripping the servo wheel with vise grips.
Cycle it back and forth a few times to get an accurate position that takes up any small slack in the cables.
Note down the "servo measured" value on the screen. Then wind the servo around to the opposite limit, note this value down.
Then in the servo screen you can enter the two values of fully up, and fully down, with an rpm span between them.
Use a few of the extra points in between, so you can, if needed, force a non linear movement with rpm ie not a straight line.
Hit program, turn off the ECU, turn it on again, and it will cycle up and down,as it has been programmed.
You can check the up and down positions and compare the "servo measured" to the "servo desired" on screen, in real time.
The hysteresis should be set usually at around 100mV, less will speed up the response, but go too low and the servo will "hunt" around the values programmed.
The RZ servos are all getting old and shagged - the newer R1 servo is mechanically very similar but uses a special molded in plug - I have the right ones to match.
The R6 and ZXR ones are not as well made, the shaft isnt supported at both ends properly.
Here is a sample wiring setup and a PV curve, set to start opening at 7200 and full open at 9000, with about 1V of span between.
You could use this to rotate a spool like an RZ, a blade like a flat PV or even the 1/2 throttle plate if you wanted to.



Something to think about while the rest of the family occupy themselves with buying, boiling, painting, hiding, searching, finding and eating easter eggs: a couple of recent videos from the Dutch 50 cc scene.
http://www.youtube.com/watch?v=mvV4xbFKs0g&feature=relmfu
http://youtu.be/0odVzSgufjk


It was designed and built by Richard Maas http://www.adriaanmeeuwsen.nl/team-pagina.html. Hopefully we will see it in action next monday.
And if I were you, I would make it go shorter with rpm :whistle:.


:niceone::niceone:
I'm impressed with how it slips all nice and steady!

Frits, may I ask, wouldn't it affect the 1st pressure wave in the diffuser, when fully inserted? -in a way to have a measurable impact on pipe effects I mean


You may. It will affect all the waves in the pipe. And it does have a measurable impact on pipe effects :2thumbsup .
But I suspect you are referring to the header intruding into the diffuser. It doesn't. Even in the shortest position everything is smooth inside the pipe.


More news from Richard Maas. Did his trombone pipe give the desired results? O yes. At 10,000 rpm it gives 4 HP more than the same engine with a fixed pipe. It runs over 17,000 rpm without the need for a powerjet and with a fixed ignition timing. It is miles better than an engine with an exhaust power valve. And the mapping of pipe length, ignition timing and powerjet pulse width has yet to be carried out. Maybe the powerjet can disappear altogether.
Only problem so far: the piece of pipe that is fixed to the cylinder, is shrouded by the pipe that slides over it, so it gets very hot. Too hot for the Viton O-ring that is taking care of sealing. Any bright ideas, anyone?

I came upon this today.

Slippy exhaust pipes
Why they're so difficult to pull, and how to fix it...
There has recently been a thread on the Mailing List in regards to the amount of effort required to "pull" the typical slippy (adjustable) exhaust pipe that is common in many road racing classes.
Well... A bit over 20 years ago, I had the same frustration, and I'll explain what I found, and how I solved the problem.
The image below show's an approximation of a "typical" slippy exhaust pipe. I have not shown the outlet hole in the "can"... (and a number of other things are missing as well), but this will serve the purpose for now. The moveable rear (convergent) cone is shown in its "out" position by the blue lines... and in it's fully "in" position by the green lines. The thick magenta line is a rough representation of the cable which pulls the rear cone/stinger assembly.
http://www.muller.net/mullermachine/docs/exhaust1.gif
OK... here's the problem in a nutshell: The amount of effort required to "pull" the rear cone is directly proportional to the difference in pressure between the front and back sides of the moveable cone. (There's some other minor things like friction, but they're insignificant compared to the pressure differential).
Since the the rear cone (at its big end) does not fit the large center section perfectly, some "pressure" leaks by the outside of the cone into the area behind the cone. If the outer rear cone (the one that supports the stinger) has too much clearance on the stinger (where I wrote "Here's the problem"), then the pressure behind the rear cone can "bleed" into the can (which has lower pressure than the inside of the exhaust pipe). This results in a pressure differential between the front (engine) side of the rear cone, and the back side.
THAT is what you are pulling "against" when you try to pull in your slippy pipe.

Now here's how I fixed the problem...
Years ago, Hartman Engineering made some very nice spun "outer" rear cones especially for slippy pipes. I started with one of those. They were made with a very large hole on the small end. (Oh... the other thing that was really nice about those Hartman cones is that they were very short. This allowed you to get the weld to the center section a long ways away from where the adjustable cone would be sliding.... which made it easier to keep the center section nice and round).
I made an insert for the small end of this cone (shown in red in the drawing below). This "insert" had a bit of a "bell-mouthed" shape to the inside diameter. I did this so that I could run a very tight fit to the stinger, without the stinger "binding" due to any misalignment that might exist. I also took the stinger material (before welding it to the cone) and had it hard-chromed, and then ground the outside diameter. This made it perfectly straight and round, as well as giving me a super fine finish that would resist any sort of galling or seizing. I gave the insert about .005 clearance on the stinger (as I recall).
How did it work?
Too well. At the time I was running Open class. Due to the power, Open engines were notorious for being almost impossible to pull the exhaust pipe for the full race (an hour long at the time). My first time on the track with this pipe was a complete surprise. The very first left-hand sweeper I went through, the rear cone went all the way in by itself, just from cornering force! The pipe was actually far too easy to pull. My solution was to experiment with "vent" holes into the can. With the clearance that I had given the stinger in my "support sleeve"... as well as the fit of the large end of the cone in the center section of the pipe... I ended up running a 3/16" diameter "bleed hole" from the outer rear cone (the short steep one in the drawing below) into the can. This gave just about the perfect "feel" in my case. I could operate the pipe handle with one finger... yet there was enough pressure on the cone to move it back out fairly quickly when I let go of the handle.
http://www.muller.net/mullermachine/docs/exhaust2.gif
You may not care to build your own slippy pipe... and we're seeing less and less classes where slippys are allowed... but hopefully this might help some of you that still run them.
Just remember: the effort required to pull the rear cone is directly related to the pressure differential on the front and back sides of the moveable cone. Anything you can do to prevent leakage around the stinger and into the can will make the pipe easier to operate... up to the point (I discovered) where it's too easy.



There are several options in lengthening a pipe. You can move the end cone, like on the above drawing, or you can lengthen the header, like on the trombone pipe.
The gas pressure generates a force that is proportional to the cross section area of the moving part and proportional to the pressure difference at either side of that area. For a moving end cone this force can be up to 4 times larger than for a sliding header. That is one reason to go for the trombone system rather than the moving cone system.

The second reason: say you wish to lengthen the total length of the pipe by 10 %. If you do it by moving the end cone, you will also enlarge the pipe volume by a little over 10 %.
But in a good pipe configuration the header length is about 1/3 of total pipe length, so in the trombone system, lengthening the pipe by 10 % will result in lengthening the header by about 30 %. That gives a far greater variation in the pipe's Helmholtz frequency than a 10 % volume change.

It is true that the length percentages of all pipe components should be in a rather fixed relation to each other. Varying the lengths of all components by the same percentage would be the theoretical optimum, but that is not feasible.
Lengthening the belly will disturb the optimum relations, as will lengthening the header. So the pipe in its lengthened version will not be the optimum for the low resonance rpm dictated by the length. But it will be a hell of a lot better than using an exhaust power valve that spoils the 180° effective exhaust timing, necessary for true resonance.
And a pipe shortened beyond its optimum may not show the optimum length relations between its components either, but it will be a lot more effective in overrev than artificially raising the exhaust gas temperature by retarding the ignition, or by weakening the mixture strenght through closing a power jet, which has the disadvantage that not all inhaled air is used for combustion.

[TZ350]

262505

130mm Trombone Header

After playing with EngMod2T for a bit I found that the interesting thing about the pipe elements needing to stay within certain percentage limits is that when you reduce the headers length, like in the Trombone arrangement the overall tuned length also reduces so the headers percentage of the overall length does not get out of balance as quickly as you might think.

[SS90]

heres a port map and exhaust diamentions and cylinder head insert. the ignition ducati energiser( kart ignition) mikuni 34mm flatslide. i did a leak test before pulling it a part at 6psi for 6mins and it was fine.i think the problem has been poor carb set up and probably ignition. the b10es plugs oiled up quickly at low revs looked to be slighty rich on inspection after a unexpected plug chop oppertunity!262447262448262449

A B10 plug? Why is that? I have no experience with Bantams (other than my old man had one when he was a spotty yuoef), but even on a tuned up one it seems a bit cold...... There are plenty of Euro build air cooled smokers pumping out serious PS with hotter plugs than that. (I assume a Bantam is Piston ported going by your port map).... If so, there is easy power to be made judging by what you have posted. If you can bring your cylinder, head, cases, piston,ignition and exhaust to Waterloo in London sometime in the next two weeks I can liberate a few nags from the celler for nix. PM me if you like. (something like a working holiday)

[crazy man]

heres a port map and exhaust diamentions and cylinder head insert. the ignition ducati energiser( kart ignition) mikuni 34mm flatslide. i did a leak test before pulling it a part at 6psi for 6mins and it was fine.i think the problem has been poor carb set up and probably ignition. the b10es plugs oiled up quickly at low revs looked to be slighty rich on inspection after a unexpected plug chop oppertunity!262447262448262449do you know dr john here in nz . he is Bantam bad

[SwePatrick]

Hello guys..

I just have to say, a really really interesting thread.
took me 2 weeks to read it.(on sparetime at work)
And when i´m saying interesting i mean INTERESTING!!!!

Still taking i glimpse here and there to see if it has been updated.

I´m building a 'overkill' Honda MB5 here in Sweden and got much much good info here.

A preview pic:

https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-ash3/564285_10150714075114475_540649474_9804621_1310594 736_n.jpg

Not complete at all on the pic,, but in progress.

[Yow Ling]

Hey Swepatrick, that looks pretty cool, what cylinder is it? Is there a race class for it?

[Yow Ling]

Did some messing round tonight , bored the cases to take a rz barrel. Dont have any idea if its clever or dumb yet, Monique can tell me
I have a bucket with a tf100 in it that I can test it in
262527262528262529262530.

[SwePatrick]

Hey Swepatrick, that looks pretty cool, what cylinder is it? Is there a race class for it?

Hello..

this bike isn´t for GP racing.. it´s for dragracing and topspeed events in Sweden for 'Mopeds'
It´s an old Kawasaki KX125 cylinder either -86 or -87.
I have bored it up to 58mm and with 49.5mm stroke(MT8 crank) it is now 136cc

A quick spec:

Kawasaki cylinder 58mm bore with woessnerpiston, new nicasil
'torus' combustionchamber 13-1 in ratio
V-force reeds
two carbs one 36mm and one 40mm(Mikuni TM/TMX)
Samarin CR125 rod, to get 1mm bigger wristpin and a little bit longer to fit better in cylinder, std is ~100mm now it´s 105mm, and finally bigger big end bearing.
Calculated exhaust(in progress right now)
6spd gearbox
Cylinder and exhaust tuned to get peak hp at ~12000rpm and ~1000rpm 'overrev'.

will build two models of clutch, one 8pcs and one 'slipclutch' with centrifugal weights.

the moped itself is an strengthened MB5 with uprated suspensions.
then lengthened and lowered to get some kind of good highspeed behaviour.

Rgds.
Patrick

[bucketracer]

Did some messing round tonight , bored the cases to take a rz barrel.

262562

A reed valve cylinder on a rotary valve bottom end. Could the cylinder be turned so you could more easily fit a Trombone pipe and the reed valve cavity used for a variable crankcase volume or better yet fit an exciter to it that sends the case volume into resonance. 12,000rpm is only 200Hz, there must be all sorts of audio drivers that could be used.

[bucketracer]

Hello guys.
I´m building a 'overkill' Honda MB5 here in Sweden
Not complete, but in progress.

That's pretty interesting, any other pictures of moped sprinters?

[dinamik2t]

or better yet fit an exciter to it that sends the case volume into resonance. 12,000rpm is only 200Hz, there must be all sorts of audio drivers that could be used.

I 'm not sure whether this is the right way (one sample per cycle) to approach it.:( But anyway, sampling freq should be at least double the signal, ie >400Hz, to avoid anti-aliasing.
Nevertheless, audio cards support frequencies close to 100kHz, so..

[Yow Ling]

262562

A reed valve cylinder on a rotary valve bottom end. Could the cylinder be turned so you could more easily fit a Trombone pipe and the reed valve cavity used for a variable crankcase volume or better yet fit an exciter to it that sends the case volume into resonance. 12,000rpm is only 200Hz, there must be all sorts of audio drivers that could be used.


Cylinder can be turned around, exhaust points downwards so would need to remove the old gp air hole. I was going to make a stuffer to fill the old inlet and use the boysen port to feed the boost post that way the sleeve can cover the old inlet ports. Exciter ? we dont need any of your fancy talk round here yet, havnt done any of the tricky stuff yet. Was struggling to hold it in the mill, rigid enough to bore the spigot, had a small emergency and thought the cases were going to be smashed , like what happens to so many fxrs without my machining help

[TZ350]

Nice!
In the tripple ex setup, perhaps you should rise the TFRs a little more.
And on a side note: in the sim, I always see a drop in power when Aux. Exs are at the same opening height as the main. I believe it's best to 'retard' them about 3-5 degrees.

I am a bit stuck with the timings as I cut the secondry exhaust ports a bit big. It was my first effort and more about seeing if it could actually be done.

At 116 the front transfers come very close to the underside of the side exhaust ports so I cant move any more there and the rear transfers need to open a little later than the fronts, so its all a bit compromised really.

I originaly wanted to make a broad spread of power but have allowed myself to get distracted by the side show of building a racing Bucket engine that reliably makes over 30hp and my tripple port is aimed at that.

262591 262592

50hp 125 Aprilia racing engine.

Side Ex boost ports are the way to go to get the blow down STA needed to make real power and to allow a smaller width main exhaust port for piston/ring reliability.


I have had some concepts about auxillery exhaust ports explained to me, and the crux of it was that not all calculated auxillery exhaust port time area is applicible, and the main advantage is not time area as such, but rather improvement of scavenging of the exhaust port when the piston is halted at BDC... better for touring engines than racing engines.

In all fairness, there are other people in the Tuning Industry that have their own ideas about the worth of Ex boost ports for racing .....

262570 262571

I think they are the Bizz but don't like wasting good cylinders on experiments, so I used an old damaged cylinder to see if it was actually possible to cut these side ports, turned out OK but not to sure about racing reliability. Although the main exhaust port is not as big as the 31hp cylinder that failed at Kaitoke so that must help.

Should be interesting on the dyno ....... and if its any good then we will see if it holds together on the track.

[dinamik2t]

Yes, unfortunately it seems there's no room for more duration. Perhaps you could try the Aprilia pattern, with the B tfr higher than the front one.
And your vertical deviders are quite wide, if you need more TFR t-a!
Have you tested the new piranha pipe yet?

[TZ350]

Have you tested the new piranha pipe yet?

The 31hp single Ex port cylinder was not supposed to destroy itself at Kaitoke as the Piranha pipe was designed for it and was scheduled to be tested after that meeting. I have had to make a new head and copper cooling fin arrangement and re-jiged the tripple port to better suit the Piranha. I hope to get the engine all back together for testing in the next few days, fingers crossed.

[dinamik2t]

fingers crossed.

I can spare 2/20 of mine also for a few days.
I would love to see a video from a dyno session, if you have the equipment!

[TZ350]

I would love to see a video from a dyno session, if you have the equipment!

Will see what can be done, if there is a spare pair of hands at the time its easy enough to make video clips for youtube with my camera.

The plan is to try the Pirana pipe and setup a safe ignition curve for it.

Then compair a 30mm OKO carb to the 24 OKO taper bored setup.

And if there is a real difference between them, try the Plenum again to see if it can overcome the restriction imposed by the 24mm carb.

Previously the plenum worked in so much as, it was able to be ridden around but at the time the restriction on power turned out to not be the 24mm carb but the lack of real blowdown STA so the plenum did not show any significant gains and there were some practical difficulties with lubrication.

Anyway if the 24mm carb looks like it has now become a real restriction then we will try the plenum idea again.

[wobbly]

Rob you could look at lifting the B,C transfers like Aprilia, and move the front of the Ex Boosts forward to gain more blowdown to suit, as the bridges
on each side of the Ex are wide - will heat up alot and expand out toward the piston - eek.

[dinamik2t]

Regarding a proper timing curve, you could find the max torque rpm from EngMod and -as Wob pointed in the past- set 28* at the mid RPM, when pipe effect starts, then 13-14* at max torque RPM and caclulate the in-between from those two.

Wob, do you think that the purity traces from Post2T can be used as an accurate tuning indicator?
I have been testing an Aprilia-like pattern, with 116-115-115 TFRs and the C-port had very low purity -unless I decreased it's timing a couple of degrees. It didn't have an impact on power, but then again scavenging was RS125-type.
Is this indicative of what happens or it's best not to rely on that parameter, since the sim already uses a fixed scavenging pattern?

262581

[TZ350]

Rob you could look at lifting the B,C transfers like Aprilia ....

Does someone have the numbers for the Aprilia handy?


move the front of the Ex Boosts forward to gain more blowdown to suit, as the bridges on each side of the Ex are wide

Do you mean narrowing down the area between the Ex boost port and main Ex port?


.... as the bridges on each side of the Ex are wide - will heat up alot and expand out toward the piston - eek.

Yes eek is right, I am not to sure about this bit myself and had thought about releving them a bit.

[dinamik2t]

Here's the EngMod equivalent of Aprilia Tfrs. It a mix of RSA/RSW cylinder derived from Frits' info on durations and data from the whiteprints from his files. But don't take the radial angles to be 100% correct. :no:

262585262586

As for the bridge between main & auxiliery exhaust. A couple of lubrication holes on the piston or a vertical lubrication band, like the aprilia piston below, would mess with the transfers??

262587

[TZ350]

Thanks for that .....

[husaberg]

Here's the EngMod equivalent of Aprilia Tfrs. It a mix of RSA/RSW cylinder derived from Frits' info on durations and data from the whiteprints from his files. But don't take the radial angles to be 100% correct. :no:

262585262586

As for the bridge between main & auxiliery exhaust. A couple of lubrication holes on the piston or a vertical lubrication band, like the aprilia piston below, would mess with the transfers??

262587

http://i1007.photobucket.com/albums/af200/motoholic71/fo110.jpg

[wobbly]

The Aprilia has the B,C ports opening 1* before the A port.
So you could leave the A port at 116 and open the rest at 115.
This will of course drop the Bl STA, so to get it back you may as well reduce the bridge width to gain some area.
Reducing the area reduces the heat soak into the bridge,thus reducing the expansion.
But it also reduces the support area for the ring and piston.
You choose the compromise.
Having all 3 ports open together will lower the midrange power, so you could also lift the main port a little to get some stagger as well as widen the top of the Aux.

The purity in the ducts is a function of the fact that the port (s) that open first, flow last due to reverse flow of the blowdown pressure into those ducts.
Thus they will have more impurity than those that open later.
You cant change the fact that the excess blowdown has to go somewhere, you choose the scavenging pattern to get the STAs needed, and you live with the result.

[SwePatrick]

TZ350..

I have ported my Kawasaki cylinder like this:
https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-ash4/421767_10150618513439475_540649474_9474811_4947466 40_n.jpg

Hard to see, but the A transfers are a couple of degrees higher at the rear end.
And then the B,C ports are all equal as rear of A port.

Mine are open in 138Degree duration and the front of A transfers are open 136.
Exhaust is 198degree´s

[dinamik2t]

Woah, 111/112 degrees! Isn't that a lot? I think you would lose a lot of power with those timings! And there seems to be quite a lot of area to be gained from the dividers.

[SwePatrick]

Nah.. i guess i will win power ;)
this is a 'dragrace' machine so 'low end' torque isn´t important.
and i wanted to keep torque low as the gearbox will have problems enough ;)

The gearbox is really closeratio, it´s setup for an 80cc machine.
So i wanted to keep the rpm range as an 80cc.

I also got an other moped that you can see in the background of first pic i posted, this is an hybrid from an MT5 and an CR80 liquidcooled engine, bored out to 88cc
that one got even harder durations. spool opens at 111 and boost at 109.5.
This one revs about 15k.
Really nasty one, hehe.

As for regaining area with porting out the dividers is true.
But i havent got the tools to get it proper ported all the way to the crankhouse.
I felt it might be unaligned in directions i want the flow.
More important than area i have learned through the years.

as it is now i have already altered the A spool to get them more aligned to the back of the cylinder.
If i want more area i have to port it all the way, my tools don´t allow that to be done nicely.

always compromises in porting an already existing cylinder. :(
If i had the knowledge and tools of casting my own, then the story will differ a lot.

Rgds.

[speedpro]

I'm running an MB5 6-speed box in my MB100 with a modified MB100 clutch with an extra pair of plates. It's making good power and the gearbox handles it without a problem. I don't think you will have a problem with the 6-speed from the original 50cc engine. FYI - the MB100 clutches drop straight in as all the shaft diameters are the same and with the extra pair of plates handle high 20s hp with stock springs. I've had a couple of MB100 that revved to 14,000rpm and nothing has come apart yet, except when I screwed up.

[SwePatrick]

Yes.. ~ 20hp is good..
But i reckon i will double that atleast.

My 88cc machine got 5disc clutch with uprated springs, it slips from time to time.
And in dragracing the dog in the gearbox are living an hard life.
any defects and the shiftforks takes the beating and snaps.
My 88cc machine is in the area around 20hp at the wheel.

https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-snc6/253781_10150214618249475_540649474_7419375_7240948 _n.jpg

that´s a pic of my 88cc hybrid.
from the beginning a watercooled cylinder, shaved off the waterjacket and replaced it with cooling fins like an std MT5 cylinder.

Quick spec 88cc:
CR80 crank
NSR50 gearbox
5disc clutch
PVL ignition
Mikuni TM28ss bored out to 30.8mm
V-force reeds
Modified Suzuki RM85 -04 exhaust.(to raise the rpm level, not perfekt i know but the moped runs hard)
Wiseco piston

PICS: 88cc
https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-snc7/59347_434338379474_540649474_5227523_7072134_n.jpg
https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-snc7/156776_477514024474_540649474_5954235_7597157_n.jp g
https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-snc6/162876_477513864474_540649474_5954230_3218643_n.jp g

My 136cc project is an 'hybrid' that too.
I have built an clutchcase that gives room for 8discs.

[speedpro]

Yes.. ~ 20hp is good..
But i reckon i will double that atleast.

You will definitely have to keep us up to date with how that goes. Couple of us have cracked 30 at the wheel and Rob is looking at even more. 40hp would be quite an achievement.

[TZ350]

262645

Red line is Speedpros 30hp at the rear wheel MB100 which has a better spread of power than my 30hp GP125 Blue line.

[Moooools]

Yes.. ~ 20hp is good..
But i reckon i will double that atleast.

My 88cc machine got 5disc clutch with uprated springs, it slips from time to time.
And in dragracing the dog in the gearbox are living an hard life.
any defects and the shiftforks takes the beating and snaps.
My 88cc machine is in the area around 20hp at the wheel.

https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-snc6/253781_10150214618249475_540649474_7419375_7240948 _n.jpg

that´s a pic of my 88cc hybrid.
from the beginning a watercooled cylinder, shaved off the waterjacket and replaced it with cooling fins like an std MT5 cylinder.

Quick spec 88cc:
CR80 crank
NSR50 gearbox
5disc clutch
PVL ignition
Mikuni TM28ss bored out to 30.8mm
V-force reeds
Modified Suzuki RM85 -04 exhaust.(to raise the rpm level, not perfekt i know but the moped runs hard)
Wiseco piston



That is very interesting.

Is there a good reason why this couldn't be done to get a 125cc aircooled cylinder that is all nice and modern. I don't know what is the best starting point but maybe Aprilia RS125? Surely you could stack it full of cooling fins too if you bunched them up. And machine a new head from scratch.

I kind of like that backwards thinking. And seems an easier option than resleeving/destroking.

[TZ350]

That is very interesting. Is there a good reason why this couldn't be done to get a 125cc aircooled cylinder that is all nice and modern. I don't know what is the best starting point but maybe Aprilia RS125? Surely you could stack it full of cooling fins too if you bunched them up. And machine a new head from scratch. I kind of like that backwards thinking. And seems an easier option than resleeving/destroking.

We have thought about it and there were some early aero cylinders with copper finning pressed onto them. Unfortunatly the way the cylinder head studs are arranged on the RGV cylinders we have, make it difficult. There is an Aprilia 125 cylinder somewhere here at work, I will dig it out and have another look. Interesting to see someone has actually done it, good work.

[cotswold]

That is very interesting.

Is there a good reason why this couldn't be done to get a 125cc aircooled cylinder that is all nice and modern. I don't know what is the best starting point but maybe Aprilia RS125? Surely you could stack it full of cooling fins too if you bunched them up. And machine a new head from scratch.

I kind of like that backwards thinking. And seems an easier option than resleeving/destroking.

Just my 5 cents worth, his bike is a 1/4 mile drag bike which would be run for 10-15 secs am guessing, we would be looking at running 10-15 minutes, cooling is not such a big deal for a few seconds but is quite important over 15 minutes.
Will be keen to see how this goes as an A/C 125 Aprilia or Cagiva has a certain appeal.

[Moooools]

Just my 5 cents worth, his bike is a 1/4 mile drag bike which would be run for 10-15 secs am guessing, we would be looking at running 10-15 minutes, cooling is not such a big deal for a few seconds but is quite important over 15 minutes.
Will be keen to see how this goes as an A/C 125 Aprilia or Cagiva has a certain appeal.

Well TZ seems to be managing okay with air cooling. And if you are making the fins yourself it would be easy to get it right (radially protruding fins on the head and closely spaced fins on the barrel. Plus you would get the benefit of an Al bore.

It would be best to cut the jacket off and then have it 3D scanned, CAD up the fins and have them laser cut so they are a nice fit. They wouldn't be the easiest thing to get looking good by hand.

[dinamik2t]

Question: What difference a Drag curve is supposed to have from a RoadRace curve?
In a 125cc engine for Roadrace, say the best would be 50hp at 12.5k, with lots of overrev. The corresponding Drag best what should be like? Lower revs for more torque and as much power as possible?

[F5 Dave]

Hello guys..

I just have to say, a really really interesting thread.
took me 2 weeks to read it.(on sparetime at work)
And when i´m saying interesting i mean INTERESTING!!!!

Still taking i glimpse here and there to see if it has been updated.

I´m building a 'overkill' Honda MB5 here in Sweden and got much much good info here.

A preview pic:



Not complete at all on the pic,, but in progress.
Aww, I'm coming over all nostalgic like.:first:

Those front ends are dreadfully bendy, even if corners don't figure. I bored the top plate & welded on some clamps cut from another bottom clamp & this stiffened things up & allowed me to drop the front end down an inch or so. The rear sw mount is pretty unconnected & a brace above the pivot works wonders, but watch the chain run.

[jasonu]

TZ350..

I have ported my Kawasaki cylinder like this:
https://fbcdn-sphotos-a.akamaihd.net/hphotos-ak-ash4/421767_10150618513439475_540649474_9474811_4947466 40_n.jpg

Hard to see, but the A transfers are a couple of degrees higher at the rear end.
And then the B,C ports are all equal as rear of A port.

Mine are open in 138Degree duration and the front of A transfers are open 136.
Exhaust is 198degree´s

Kawasaki what?

[husaberg]

Just my 5 cents worth, his bike is a 1/4 mile drag bike which would be run for 10-15 secs am guessing, we would be looking at running 10-15 minutes, cooling is not such a big deal for a few seconds but is quite important over 15 minutes.
Will be keen to see how this goes as an A/C 125 Aprilia or Cagiva has a certain appeal.

It certainly does have an appeal but the 24mm carb with a reed valve is off putting. i am musing the reed valve motor may suffer more with the restricted carb size than say the Disk valve engine such as Tz's does.
Peter Jones (oyster) i understand has previously done a AC RG125 conversion. I have no details regarding it's performance maybe Yow or Kicka can add something?
I would also guess the fuel rules for the drag motor could allow methanol as well. I remember some 70's drag bikes used to cut off fins and also some water cooled ones used to run without water to allow for faster warm ups so as to minimise the running time of the highly strung engines.

[F5 Dave]

I am a bit stuck with the timings as I cut the secondry exhaust ports a bit big. It was my first effort and more about seeing if it could actually be done.

At 116 the front transfers come very close to the underside of the side exhaust ports so I cant move any more there and the rear transfers need to open a little later than the fronts, so its all a bit compromised really.

I originaly wanted to make a broad spread of power but have allowed myself to get distracted by the side show of building a racing Bucket engine that reliably makes over 30hp and my tripple port is aimed at that.



50hp 125 Aprilia racing engine.

Side Ex boost ports are the way to go to get the blow down STA needed to make real power and to allow a smaller width main exhaust port for piston/ring reliability.



But in all fairness, there are some people with experiance in the Tuning Industry that have differing ideas about how worth while extra Ex boost ports are for racing .....

262570 262571

I don't like wasting good cylinders on experiments, so I used an old damaged cylinder to see if it was actually possible to cut these side ports, turned out OK but not to sure about racing reliability. Although the main exhaust port is not as big as the 31hp cylinder that failed at Kaitoke so that must help.

Should be interesting on the dyno ....... and if its any good then we will see if it holds together on the track.
TZ, just looking at the pics (which look well cut) it would seem the subs will bleed into the transfers, have you made flush pin plugs? I am surprised at Wob's comments about the hot bridge, when I'd done it I'd assumed the extra area would give support & not overheat, but I suppose it isn't attached to a particularly well cooled area.

My CPI barrels have some area there. Hmm Perhaps that's a clue. There have been some issues there.

What engines have had this indicate the behaviour Wob? It is easier to cut them further forward, but I'd been scared to & wanted to connect as much ally into the passage as possible.

[SwePatrick]

Kawasaki what?

Kawasaki KX125 -86/87 something.
cylinder got KIPS, i have kept it to see if i can adjust the curve with different settings on valves.
But no automatic adjusting, as it is hard to build it onto the Honda engine ;)

[TZ350]

Ok, dug out some cylinders and took some photos.

I think the bulk of the heat that needs to be lost from the cylinders cooling system mostly comes from the underside of the exhaust port duct, the top of the upper cylinder and the top of the transfer ducts when hot exhaust gas enters them after the blow down STA has become to short for the RPM.

I don't think that just cooling the upper cylinder would be enough for road racing.

262662

Aprilia 122

There must be a good reason that cooling water enters the cylinders around the exhaust port first. It could be an issue air cooling the underside of the exhaust tract properly.

262663

It does look like it would be possible to cut the water jacket away enough to get fins onto the upper part of the cylinder but as the bulk of the heat comes from the exhaust port area and the top of the transfers. Getting enough good finning onto them to cool them adequately looks a bit harder.

262664

Still the Aprilias inlet looks like it is made to do the business.

262666

RGV250

Same issues cooling the exhaust port area.

262665

Another problem with the RGV cylinder is the head studs, if you cut the water jacket away you loose the head stud holes.

262661

I had thought about putting the fins on the outside and filling the water jacket with fine copper dust and cooking oil for heat transfer.

[TZ350]

TZ, just looking at the pics (which look well cut) it would seem the subs will bleed into the transfers, have you made flush pin plugs?

No plugs, it wasn't planned they just grew that close.


I am surprised at Wob's comments about the hot bridge, when I'd done it I'd assumed the extra area would give support & not overheat, but I suppose it isn't attached to a particularly well cooled area.

Me too, I would have thought wider would be better too, I will just have to suck it and see now.

[SwePatrick]

About heat in my 88cc machine.
A little powerloss thou.. but i bored the cylinder a couple of hundreds bigger.
In other words: i got instead of 0.07mm clearance for piston i got 0.09 in clearance.

this is also good with all forged pistons to do as they are prone to seize a bit.

I bored my 136cc project 58.02mm instead of 58.00.

this allows the piston to take som more heat before it smears on the cylinderwall and ruins the day at the track.

easy to understand why,,, i haven´t got GP budget and wan´t to race all summer.

Rgds
Patrick

[husaberg]

Ok, dug out some cylinders and took some photos.


There must be a good reason that cooling water enters the cylinders around the exhaust port first. It could be an issue air cooling the underside of the exhaust tract properly.



262661

I had thought about putting the fins on the outside and filling the water jacket with fine copper dust and cooking oil for heat transfer.
Why not absorb some of that heat as well instead of just transferring it
Specific heat values of common materials: (not conductivity)
Material Specific Heat
(kJ/kg/degree C)
Water 4.18
Aluminium 0.94
Copper 0.39
Air 1.01
Concrete 0.88

Instead of cooking oil I would use a solid at room temp medium with copper . but with external fining and lots of it.
Paraffin wax, , its typical characteristics are:
• Melting point: 52 degrees C
• Specific heat: 3.27 kJ per kg per degree C
• Specific heat of fusion: 210 kJ/kg
So to increase the temp of 1kg of the wax from 47 to 52 degrees takes 16.35kJ, but to push it past 52 degrees takes nearly 13 times as much energy. (Or, to risk causing confusion, you could dissipate in it a power of 14kW for 15 seconds to melt 1kg.)


Paraffin wax is non-toxic, doesn't explode (although it will catch fire if you expose it to a naked flame) and is easily handled. Special waxes designed specifically for this change-of-state heat storage purpose are also available with melting points in 10-degree C increments from 50 degrees to 100 degrees C,
But if a Wax with a melting point of 100 degrees (similar to water unpressurised boiling point) was selected and some external source of fining was available to help dissipate the heat?
Would it still be air cooling? would it work? fiik

But then again as you see water cooling is still far more efficient. 4.18 vs 3.27 kj/kg per deg C

[wobbly]

As with most things we deal with there is two sides of a coin involved that leads to having to compromise.
A bridge with a smaller area/volume will expand less,but of course it also has less face area to support the piston/ring.
The ultimate expression of this is the Aprilia that uses as much area as possible to gain Blowdown STA.
The opposite is the CPI cylinders that have alot of material between the main port and tha Aux.
I needed alot of blowdown in the RZ400 cylinder to make 120CHp so the width has been halved,its just about to go on the dyno
with Wossner pistons using the same ovality as the 485 with wide bridges.
The new pistons have a cutaway above the pin that extends to the bore centerline, so I couldnt go any wider the other way.
So we shall see the effect immediately.

[twotempi]

Hi guys,

I want to use a particular ProX piston but it comes with two holes drilled in the skirt for lubricating a exhaust port bridge.
My cylinder does not currently have a bridge so what are your opinions on what to do.

Possible options are

1) Do nothing to the holes. Yes, there will be some leakage but..............
2) Use say a brass domed head rivet with knurled shank inserted from inside the piston - and peened over very carefully on the outside.
3) Spot weld the holes
4) Put bridge into exhaust port - which would allow better STA as well.
5) Some other option that i have not thought of

My preferences are either 1) or 4)

What do you think?
thanks in advance

[dinamik2t]

What's the model of your piston?
Using a different brand/model, without bridge holes but similar dome/wrist pin/heights isn't an option?

[speedpro]

TZ uses pistons with holes to lubricate the ex port bridge but he doesn't have a bridge in the port. He's filled the holes with something along the lines of Devcon but super dooper. Hasn't come out yet.

[Yow Ling]

Hi guys,

Possible options are

4) Put bridge into exhaust port - which would allow better STA as well.

My preferences are either 1) or 4)

What do you think?
thanks in advance

How would you do that? I have thought along those lines , maybe if I was a gynacologist I could do it. I just not that clever.

[bucketracer]

I want to use a particular ProX piston but it comes with two holes drilled in the skirt for lubricating a exhaust port bridge.
My cylinder does not currently have a bridge so what are your opinions on what to do.


TeeZee just glues his with Belzona, when people questioned it he posted pictures of race pistons from an Aprilia or Honda RS that were done that way, now I think he intends trying Devcon.

[bucketracer]

Before I start on my Wobbly engine I wanted finish the Ex side port mods on my old air cooled engine and run it up on the dyno.

First step is to prep a new piston, I have been using a dished piston but Wob tells me they are not that great so future ones will be flat top.

230863

The oiler holes for the exhaust bridge need plugging.

230864

Normaly I would weld them but was persuaded to try glueing them with some super duper stuff thats as tough as shark shit.

And hey, this is Buckets, we are allowed to try new ideas.

So the were prept up with a dremmil.

230866

And the finished result.

230865

Then new holes were drilled for oiling the bridge between the exhaust and transfers.

230862

The Ex/Trans bridge


232140

After 40+ dyno pulls at near 30hp the glue blocking the oiler holes is still there inside the piston..


232766

Thomas comes up with the goods again......... RSA ?

232769

Transfers

232768

Main Ex Port 66% of bore

232767

Old bridge oilers glued up, so now we know for sure that gluing the piston works, just like Thomas said it would.

TeeZees posts where he talks about glueing the oiler holes.

[TZ350]

The first piston that I glued, I used Belzona, this one is glued with Devcon F.

262693 262692

A bit of prep and a thin layer of glue worked into the holes to seal them. I think a thin layer is less likely to pull lose than a thicker one.

[SwePatrick]

there´s one more way..
soldering. use alutite.

http://www.youtube.com/watch?v=OLvDHwQFvAM
http://www.youtube.com/watch?feature=player_embedded&v=zaaZ0R8-2Bw#!

[TZ350]

Took the failed piston off tonight. Not only does it have what looks like detonation damage over the exhaust port, it has turned the ring and there is a lot of mechanical damage too. The blue line is where the ring peg is.

On a positive note this piston has done many dyno runs, the full race meeting at Te Puke and a fast practice at Kaitoke and only failed during the slow warm up laps for the next session.

Looking at the underside of the piston there is the localised over heating from the detonation but no central stain on the underside of the piston crown that you would expect if the engine was generally running hot.

From comments that Wob has posted, the problem seems to have been that the ignition curve was OK for hard out full throttle work like a dyno run or hard out racing but was to advanced in the mid range when just trickling around.

[TZ350]

TZ uses pistons with holes to lubricate the ex port bridge but he doesn't have a bridge in the port. He's filled the holes with something along the lines of Devcon but super dooper. Hasn't come out yet.

262711

The glued up bridge oiling holes and one of the new holes drilled for oiling the area between the exhaust and main transfer ports.

[F5 Dave]

so you will run a TPS on a splitter cable or whatever & anything less than full run a rtd curve. Would like to see how that goes.

[TZ350]

The more tec posts from the last ten pages.....


There are several options in lengthening a pipe. You can move the end cone, like on the above drawing, or you can lengthen the header, like on the trombone pipe.
The gas pressure generates a force that is proportional to the cross section area of the moving part and proportional to the pressure difference at either side of that area. For a moving end cone this force can be up to 4 times larger than for a sliding header. That is one reason to go for the trombone system rather than the moving cone system.

The second reason: say you wish to lengthen the total length of the pipe by 10 %. If you do it by moving the end cone, you will also enlarge the pipe volume by a little over 10 %.
But in a good pipe configuration the header length is about 1/3 of total pipe length, so in the trombone system, lengthening the pipe by 10 % will result in lengthening the header by about 30 %. That gives a far greater variation in the pipe's Helmholtz frequency than a 10 % volume change.

It is true that the length percentages of all pipe components should be in a rather fixed relation to each other. Varying the lengths of all components by the same percentage would be the theoretical optimum, but that is not feasible.
Lengthening the belly will disturb the optimum relations, as will lengthening the header. So the pipe in its lengthened version will not be the optimum for the low resonance rpm dictated by the length. But it will be a hell of a lot better than using an exhaust power valve that spoils the 180° effective exhaust timing, necessary for true resonance.
And a pipe shortened beyond its optimum may not show the optimum length relations between its components either, but it will be a lot more effective in overrev than artificially raising the exhaust gas temperature by retarding the ignition, or by weakening the mixture strenght through closing a power jet, which has the disadvantage that not all inhaled air is used for combustion.


I thought that closing the power jet after peak power only restored the proper air fuel ratio? And the over rev was extended because the exhaust gas was not being cooled by an over rich mixture.



I guess that's what happens when water injection changes the temperature of the exhaust gas, water injection looks like it would be a good idea if it was practical and didnt have any down sides.



I have simulated the Slippery pipe in EngMod2T before and was not that encouraged by the results but your explanation of the Trombone looks interesting and I will try that in EngMod now.



More good old engineering and design compromises to play with.



Do I understand this correctly, given sufficient blow down and exhaust STA an exhaust duration of 180 deg would be the optimum at any rpm?

Thanks Frits ..... gives me a bit more to think about.


The short answer is yes. But why is it that each time you people sit down for five minutes to write a question, I have to sit down for two hours to write an answer?http://www.kiwibiker.co.nz/forums/images/smilies/msn-wink.gif

When the exhaust port opens, a pressure pulse starts moving through the exhaust pipe. It is reflected at the end cone and it should be back at the cylinder just before the exhaust port closes.
Next a part of this reflected pulse bounces off the partly-closed exhaust port and a residual pulse starts moving down the exhaust pipe. This residual pulse too is reflected by the end cone and starts moving back to the cylinder. Ideally it will arrive at the exhaust port just when the port opens again. Then the cylinder pressure and the pressure of the residual pulse combine their energy and the resulting pulse will be stronger than the pulse from the previous cycle. And the combined pulse from the next cycle will be stronger still, and so on; we have achieved true resonance.

Some may argue that we want a low pressure in the exhaust pipe when the port opens because then the spent gases will experience less resistance while leaving the cylinder. But that is not true. Gas flow depends on a pressure difference ratio. But once that ratio reaches 2, the flow velocity will reach Mach 1, the speed of sound. Raising the pressure difference any further will not raise the flow velocity any further.
The cylinder pressure at exhaust opening can be as high as 7 bar and the pressure of the reflected pulse will be about 2 bar. Thus the pressure ratio is well above 2, so lowering the pressure in the exhaust duct outside the cylinder will not do any good to the flow.

What has the exhaust timing got to do with the 'true resonance' I mentioned above?
The initial pulse starts moving at Exhaust Opening and it has to be back at Exhaust Closing, or a little earlier. This pulse travels with the speed of sound and its journey up and down the exhaust pipe will take t seconds.
The residual pulse starts moving at Exhaust Closing and it has to be back at the next Exhaust Opening. This pulse also travels with the speed of sound and its journey up and down the exhaust pipe will also take t seconds.
So from EO to EC takes t seconds and from EC to EO also takes t seconds. In English: the exhaust port should be open just as long as it should be closed.
Assuming that the crankshaft rotates with a uniform speed, this means that the crank angle during which the exhaust is open must be equal to the crank angle during which the port is closed. So both angles must be 180°.

I developed this line of thought some 40 years ago, but when I first published it in 1978 (in the motorcycle magazine Moto73 of which I was the technical editor) everybody called me crazy. Some people still do, but I got used to it http://www.kiwibiker.co.nz/forums/images/smilies/tongue.gif.

Above I made a couple of assumptions. The crankshaft does not rotate with a uniform speed, but at high revs the deviation is negligible. In case you really want to know, I did the math for the Aprilia RSA125. At a nominal rpm of 13,000 the minimum rotation speed is 12970 rpm @ 107° after TDC and the maximum value is 13031 rpm @ 356° aTDC. What's more significant: the deviation in crankshaft position from truly uniform rotation is always less than 1°. So that really is negligible.

Second assumption: both the initial pulse and the residual pulse move with the speed of sound. Not true: the pulse pressures in exhaust waves are so high that acoustics rules do not apply any more. We are dealing with gas dynamics here and the stronger a pulse, the faster it moves. Since the residual pulse is weaker than the initial pulse, they move at different speeds. But we will leave this aside for now.

Third assumption: the initial pulse starts moving as soon as the exhaust port starts opening. More or less true, but we are not interested in the first weak appearance of the pulse; we want to know when the pulse reaches its maximum amplitude. And that requires a certain amount of open exhaust port area. It turns out that for our desired theoretical exhaust timing of 180° we will need a geometrical exhaust timing of about 190°, depending on the shape of the port: does it open gradually or does it open over its full width all at once.

The obvious question will be: why has the Aprilia RSA125 a geometrical exhaust timing of about 200°? True, at 190° the maximum torque value would be higher, but the engine would not want to rev because the blowdown time.area would be too small.
The 200° are a compromise: a bit less torque and a bit more revs; as long as the torque decline is smaller than the rpm rise, we gain horsepower.


That Dutch trombone pipe moved from +70 mm length to -20 mm length, so its effect was concentrated on the lower revs (although raising max.rpm from 14,500 to over 17,000 rpm was a welcome bonus).


The tech term for what Frits is describing is Superposition of the Ex pulse.
This is easily described in a sim, where a residual pressure ratio is seen sitting at the Ex port when it is opening.
The "new " pulse is added to this residual, and a very large pressure ratio exits down the duct to the header.
The larger the initial ratio, the larger the amplitude of the wave in the diffuser - this creates a deeper depression around BDC, and it is this that initiates the biggest mass flow
from the transfers.
The lower Ex timings of 190 and below create larger residual pressure ratios,over a wider band, and thus these work with a good pipe design to use "resonance" to increase band width and also peak power.
Big problem though is this whole concept is at odds with maximising blowdown to allow good peak power and more importantly, overev power.

The sim shows RGV100 making serious power with the superposition pulse going down the duct - off the scale.

Re the trombone pipe results you did sims for TeeZee.
Look carefully when you say it seems to affect the top end "more ".
At 9000 the lowest reading is 13 Hp, the highest reading is 17 Hp, thats an increase of 4 Hp, thats 31% more power in the bottom end, that then allows the thing to rev to 17,000.
Seems a not bad result.

Re the powerjet temp result you mentioned.
The effect of the solenoid powerjet is as you described - this I only discovered recently with a datalogger that I could set the sample rate of the EGT high enough to read the temps quick enough - along
with some exposed junction probes.
I was testing a RS125 on the dyno and it was making NO power past 12500, looking at the data you could see the egt drop from 640 C to 580 in around 400 rpm.
After fixing the fact some idiot had left out the rpm plug in the loom, the solenoid now switched on at 12200, and the temp stabilised at 650 past 12500 and the thing than reved out to 13500 +.
So the powerjet switching isnt making the mixture "lean"as such, it is simply maintaining the correct mixture, and thus the temp in the pipe.


http://www.epi-eng.com/piston_engine_technology/comparison_of_cup_to_f1.htm

http://www.epi-eng.com/piston_engine_technology/engine_technology_contents.htm


Frits used the same example.
It would certainly help with useful overrev on tight tracks as well as when you have a wide ratio gearbox
Variable pipe lengths with length or temps
I came upon this today.

Husabergs post is worth a look.


262505

130mm Trombone Header

After playing with EngMod2T for a bit I found that the interesting thing about the pipe elements needing to stay within certain percentage limits is that when you reduce the headers length, like in the Trombone arrangement the overall tuned length also reduces so the headers percentage of the overall length does not get out of balance as quickly as you might think.


Rob you could look at lifting the B,C transfers like Aprilia, and move the front of the Ex Boosts forward to gain more blowdown to suit, as the bridges
on each side of the Ex are wide - will heat up alot and expand out toward the piston - eek.


Here's the EngMod equivalent of Aprilia Tfrs. It a mix of RSA/RSW cylinder derived from Frits' info on durations and data from the whiteprints from his files. But don't take the radial angles to be 100% correct. http://www.kiwibiker.co.nz/forums/images/smilies/no.gif

262585262586

As for the bridge between main & auxiliery exhaust. A couple of lubrication holes on the piston or a vertical lubrication band, like the aprilia piston below, would mess with the transfers??

262587


The Aprilia has the B,C ports opening 1* before the A port.
So you could leave the A port at 116 and open the rest at 115.
This will of course drop the Bl STA, so to get it back you may as well reduce the bridge width to gain some area.
Reducing the area reduces the heat soak into the bridge,thus reducing the expansion.
But it also reduces the support area for the ring and piston.
You choose the compromise.
Having all 3 ports open together will lower the midrange power, so you could also lift the main port a little to get some stagger as well as widen the top of the Aux.

The purity in the ducts is a function of the fact that the port (s) that open first, flow last due to reverse flow of the blowdown pressure into those ducts.
Thus they will have more impurity than those that open later.
You cant change the fact that the excess blowdown has to go somewhere, you choose the scavenging pattern to get the STAs needed, and you live with the result.


As with most things we deal with there is two sides of a coin involved that leads to having to compromise.
A bridge with a smaller area/volume will expand less,but of course it also has less face area to support the piston/ring.
The ultimate expression of this is the Aprilia that uses as much area as possible to gain Blowdown STA.
The opposite is the CPI cylinders that have alot of material between the main port and tha Aux.
I needed alot of blowdown in the RZ400 cylinder to make 120CHp so the width has been halved,its just about to go on the dyno
with Wossner pistons using the same ovality as the 485 with wide bridges.
The new pistons have a cutaway above the pin that extends to the bore centerline, so I couldnt go any wider the other way.
So we shall see the effect immediately.

[TZ350]

More work on the triple port cylinder.

262719

Ring ends just meet on the bridge between the boost and B transfer port. The other lines are so I can drill oilers for the bridge between the ex port and main transfers and make a port in the piston for the boost port.

262720

Piston protrudes 1.2mm at TDC.

262722

Lower cooling fin is 2mm thick.

262723

Later on I plan on using a head gasket to thermally isolate the top copper cooling fin and head from the lower copper cooling fin and cylinder so the head can run cooler than the cylinder.

262718

Checking the squish clearance, and yes its 0.8mm.

262721

How the two copper cooling fins stack on the head leaving a (will be) polished alloy combustion chamber.

[TZ350]

262724

Chambers bending up his main shock bracket, we have all the sophisticated tools like CNC folders.

262725

Chambers is making a copy of a RS125 canterlever swing arm for his RG50.

[jasonu]

262724

Chambers bending up his main shock bracket, we don't have a lot of sophisticated tools.

262725

Chambers is making a copy of a RS125 canterlever swing arm for his RG50.

http://www.youtube.com/watch?v=oVOxa9I2Obs

In reference to the tasty beverage in the last pic

[worm13]

262360262361how much would you pay for this bit of rubbish? gt50

262748

heres that photo I said I knew about and have one of a matching sidecar for it aswell

[crazy man]

262748

heres that photo I said I knew about and have one of a matching sidecar for it aswellthe sidecar looks like it has a stinger t100 in it

[TZ350]

a couple of recent videos from the Dutch 50 cc scene.

http://www.youtube.com/watch?v=mvV4xbFKs0g&feature=relmfu

http://youtu.be/0odVzSgufjk

<iframe src="http://www.youtube.com/embed/mvV4xbFKs0g" allowfullscreen="" frameborder="0" height="315" width="560"></iframe>


That Dutch trombone pipe moved from +70 mm length to -20 mm length, so its effect was concentrated on the lower revs (although raising max.rpm from 14,500 to over 17,000 rpm was a welcome bonus).


I have been looking at the Darcy RG500 pipe that peaks at 10,500 and simulating it with a Trombone header. By shortining the header 130mm It looks like I can get the power spread to extend out to 14K.

262828

The total amount of power under the curve is much greater than I had before.

After we get the triple port and Pirana pipe testing out of the way I want to try my hand at one of these Trombone pipes. They look like the key to making an all conqering 2-Stroke.

262828

The plan is to make a pipe that works well down low and then use the Trombone effect to get lots of extension of the working range. Not so much about peak hp numbers, that 2-Strokes can be good at but dramaticaly increasing the area under the power curve.

I need a Trombone section that can collapse 130mm, now there is the trick, how do I make that .....:scratch:

[dinamik2t]

Have you given any thought on the setup yet?
The dutch racer has a backward facing cylinder and a straight pipe, which makes it quite "easy" to vary its length.
On a curved header it will be challenging to come up with an efficient moving system. I like it! :d

[TZ350]

Have you given any thought on the setup yet?

One possibility is to use one of those water cooled after market 50mm big bore kits you see advertised for scooters and fit it backwards on the GP cases and have a 100cc water cooled screemer.

262830 262831

Or I could make a pipe like this one, as there is plenty of room in front of the engine I could use the the first part of the pipe as the Trombone. Or even the vertical bit could slide in and out.

262832

This is one of Speedpros pipes where the muffler comes forward instead of pointing out the back. Its pretty easy to see that if the back could pivot, the front Trombone section could move up and down easily with the pipe pivoting at the back.

[Yow Ling]

One possibility is to use one of those water cooled after market 50mm big bore kits you see advertised for scooters and fit it backwards on the GP cases and have a 100cc water cooled screemer.



Or I could send you a rz250 barrell they fit both ways on the gp cases, got a lifetime supply of them !

[TZ350]

<iframe src="http://www.youtube.com/embed/QOkGhFTEGuE" allowfullscreen="" frameborder="0" height="315" width="420"></iframe>

A "Real Mans" dyno .....

First run 19.9 hp second run 23 hp.

Actually not to hard to make with a disk brake for an energy sink and a load cell to measure the torqe.

[husaberg]

I am sure some pics of the bikes or engines have been added before a British attempt at a prepackaged Rotax tandem twin TZ beater from the 80's made in both 250 and 350cc.

Lozza will be well aware of this When i was looking for pics his name pops up quite a few times.
One thing i have not picked up on is they had mirrored disks on at least one of the bikes.
I always thought the rear disked Derbi or Aprilia was strictly for packaging?
http://4.bp.blogspot.com/_qhEyRCc7sKE/S38NUd8BUjI/AAAAAAAAAhg/VdpTz4_W7QA/s320/rsa919.jpg
but was it mainly for a better transfer layout with more symmetry as well?
Possible advantages with the twin disk i can see include a symmetrical flow and the inlets would be smaller so less obtrusive to the transfers.
It should also possibly offer better drive-ability( it does of course fail the KISS test though.)
Frits I think posted a twin disk 50 done in the 70's.


The Kreidler engine shown by TZ350 was cutting edge technology in 1962, but I do not think any of you want to copy transfer passages that, together with twin rotary disks and a twelve-speed gearbox, produced all of 10 HP out of 50 cc.
In case you wonder: the transfer timing was 142°; the single exhaust was way over 200°. Don't try this at home....
Below are some more pictures of the same engine, showing the twin carbs and the screwed-in caps that gave access to the transfer ports for easy modification.
You can also see the hand-operated three-speed gearbox behind the foot-shifted four-speed box.
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=250807&stc=1&thumb=1&d=1321437117http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=250811&stc=1&thumb=1&d=1321437680


oh to fit the trombone pipe in why not tip the motor forward TZ it has advantages being a disk valve with the side sucker carb.
The gearbox breathing and oiling will need work and the ground clearance might suffer a bit.
and yes the selector will be a bit in the way not as neat as the Rumi which was a reverse cylindered design as well.

[wobbly]

That dyno run looks more like a Hitler gas chamber than a dyno cell.
With the header leaking like a sieve and the carb sucking dirty air, no way is anything repeatable going to happen.

[TZ350]

<iframe src="http://www.youtube.com/embed/HYxs6qF6-oE" allowfullscreen="" frameborder="0" height="315" width="420"></iframe>

Here we go, a simple disk brake dyno.

[TZ350]

262856 262857 262858

The triple exhaust and Piranha pipe.

Finally sorted all the little issues and got it together. It has a great little RS(?) muffler, I hope it has the real RS sound when its on full song.

The game plan is to put it up on the dyno, check the compression and if its not crazy high, then load a safe ignition curve and warm it up. Then let it cool right off and torque the head down again before giving it a real run to see whats what.

[kel]

262857

The triple exhaust and Piranha pipe.

Finally sorted all the little issues and got it together. It has a great little RS(?) muffler, I hope it has the real RS sound when its on full song.

The game plan is to put it up on the dyno, check the compression and if its not crazy high, then load a safe ignition curve and warm it up. Then let it cool right off and torque the head down again before giving it a real run to see whats what.

Looking good!
Any chance of extending the stinger to move the muffler further away from the foot peg? That precious test pilot :apumpin: who last punted your bike was seen to slip off the left peg on more than one occasion.

[TZ350]

Looking good! Any chance of extending the stinger to move the muffler further away from the foot peg?

It doesnt have a venturi so the stinger is still part of the equation and we can't extend it, but next time your over we could try and bend it down a bit and see if that works.

[husaberg]

<iframe src="http://www.youtube.com/embed/HYxs6qF6-oE" allowfullscreen="" frameborder="0" height="315" width="420"></iframe>

Here we go, a simple disk brake dyno.


Hence the B in the BHP.<_<

why can't we just use a alternator and make something useful like er.....electricity. Rather than just heat.
We could then go all metric and measure the output in K-Watts as well:laugh:
http://t3.gstatic.com/images?q=tbn:ANd9GcTEPBxHp_EBe1zKmPXs2WmNFuK7VW9Gx Gj8ey8MTjXyUaJuGz9BIszns_uIhttp://3.bp.blogspot.com/-x9ICPVD9vWE/Ttb1qpL7AOI/AAAAAAAAAC8/xuL_QJWiKcg/s320/DEFINITION+OF+1HP.jpghttp://www.pakwheels.com/blog/wp-content/uploads/2010/11/power-300x260.jpghttp://www.makingthemodernworld.org.uk/stories/the_age_of_the_engineer/03.ST.02/03.SC.RM.09/03.SC.RM.09.jpg

http://www.youtube.com/watch?v=fg3HoWSFjiU&feature=player_embeddedhttp://www.gearfuse.com/wp-content/uploads/andrew/5_apr07/windshearinc02_1.jpg

[TZ350]

Lambretta with MAXIMUM POWER 55 HP on wheel

<iframe src="http://www.youtube.com/embed/OKNy3hGC1YY" allowfullscreen="" frameborder="0" height="315" width="420"></iframe>


I have been looking at some of the Scooter dyno runs on YouTube, here is a Lambretta that makes 55hp, I have no idea of its capacity, though its probably more than 125cc.

Most of the vespas I have seen are 18-20ps for 133cc 22-27ps for 175cc and 30-32ps for 210cc.

[wobbly]

Two things I dont get.
Why would you build an engine, put it in the bike, put it on the dyno - THEN check the com.
Doing the cc on the engine is basic task 1A.

Also, the pipe was designed specifically to use a stinger nozzle, it was also designed specifically to use 78* Ex timing.
I know this is ONLY buckets, but how the hell can a pipe I designed for an application that is completely different, and then isnt built as designed,ever going to work properly - it cant and wont.

[Frits Overmars]

Life is hard, Wob.

In the picture below, if the engine is moved still a bit further back, you might be able to fit a straigth trombone pipe between cylinder and front wheel. And who cares about front wheel load; that only affects handling...

Did I mention that horsepower can gain you tenths of seconds and handling will give you whole seconds?

[bucketracer]

Two things I dont get.
Why would you build an engine, put it in the bike, put it on the dyno - THEN check the com.

I think TeeZee probably wants to know the compression pressure for future reference and compare it to other known engines. Also he probably finds it much easier to spin the Beast over using the Dyno's starter motor than trying to pull it over by hand.

As for the stinger and port timing, there is a good chance TeeZee has taken the trouble to check it all out using EngMod2t.

[bucketracer]

In the picture below, if the engine is moved still a bit further back, you might be able to fit a straigth trombone pipe between cylinder and front wheel. And who cares about front wheel load; that only affects handling...

Did I mention that horsepower can gain you tenths of seconds and handling will give you whole seconds?

My guess is TeeZee has checked the weight distribution with rider aboard between the front and back wheels and the engine is placed where he thinks is best for handling, he may have even posted the numbers somewhere.

[bucketracer]

262885 262886 262887

Ok found the pictures.

TeeZee and Chambers put quite a bit of thought into positioning their engines.

I can't think why anyone would be silly enough to think they wouldn't have.

[Frits Overmars]

With the rider in position the weight distribution should be clearly biased towards the front. Judging from the pictures I can hardly imagine this is the case.

[bucketracer]

With the rider in position the weight distribution should be clearly biased towards the front. Judging from the pictures I can hardly imagine this is the case.

Pretty silly to jump to an assumption and poke fun, smarter to have asked.

Ok, they used old bathroom scales, and as I remember it they aimed for 52% on the front wheel with the rider in a semi upright position as they might be when turning into a corner. They also used the Mt Welly Kart scales to check their results, certainly the weight bias right or wrong was not left to chance.

[husaberg]

It's the same everywhere in racing (except dragracing): engine power may give you tenths of seconds; chassis setup will give you whole seconds.


.

One look at Fi5hys Bucket and you can see the empathise on handling and modest easy to ride power is all you need for a winner.

Thanks for your interest.....
In the team there are two Honda RS125 chassis with Suzuki GP125's in them, from memory, all up they weigh about 75kg, the handling is superb and the young guys who ride them swear by them, but they can be cramped to ride.
And there are two Yamaha FZR250 chassis with GP's for those on the team who prefer armchair comfort with their racing. the FZR's at 81 and 93kg weigh about the same as the 90kg stripped down Suzuki GP125's they replaced. One of the FZR's has wire wheels and is 12kg lighter than the other one.
9kg diff in the wheels and another 2-3kg in the smaller disk, calipers, cut down sub frame and lighter chamber. The FZR's look big but are 10+kg lighter than most Suzuki FXR's which are typically 105-110kg.
In running the FZR's we are looking at riding comfort and better handling than the old Suzuki GP chassis could manage. We are getting reasonable hp but figure good handling will get us further now than extra hp will. There are three F5 bikes, two runners and one a work in progress and two of the old Suzuki GP's are going to be kept on as loan bikes when we can get some good standard engines for them.
Only one of the FZR's is on the track at the moment, it took 250 hours of work to get it there. The other is still a little way off yet but getting there. Most of the team and particularity Chambers try to do an hour or two on their projects most nights. I post what I can of what they are up too. Speedpro also runs an FZR with a very quick Honda MB100 motor, he is the one who got us interested in them.
So everyone is right ok.
But
Come on guys i am sure it would be more fun to take this to the chassis thread. http://www.kiwibiker.co.nz/forums/showthread.php/145224-Race-chassis

i am sure Fits is literally chomping at the bit to answer my musings on the reasoning of the rear disk or twin disk valves. posted back a page.

I am sure some pics of the bikes or engines have been added before a British attempt at a prepackaged Rotax tandem twin TZ beater from the 80's made in both 250 and 350cc.

Lozza will be well aware of this When i was looking for pics his name pops up quite a few times.
One thing i have not picked up on is they had mirrored disks on at least one of the bikes.
I always thought the rear disked Derbi or Aprilia was strictly for packaging?
http://4.bp.blogspot.com/_qhEyRCc7sKE/S38NUd8BUjI/AAAAAAAAAhg/VdpTz4_W7QA/s320/rsa919.jpg
but was it mainly for a better transfer layout with more symmetry as well?
Possible advantages with the twin disk i can see include a symmetrical flow and the inlets would be smaller so less obtrusive to the transfers.
It should also possibly offer better drive-ability( it does of course fail the KISS test though.)
Frits I think posted a twin disk 50 done in the 70's.


http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=250807&stc=1&thumb=1&d=1321437117http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=250811&stc=1&thumb=1&d=1321437680


oh to fit the trombone pipe in why not tip the motor forward TZ it has advantages being a disk valve with the side sucker carb.
The gearbox breathing and oiling will need work and the ground clearance might suffer a bit.
and yes the selector will be a bit in the way not as neat as the Rumi which was a reverse cylindered design as well.

There is a 6 speed casette box on TM at the moment
http://images.trademe.co.nz/photoserver/tq/37/215041737.jpg http://www.trademe.co.nz/Browse/Listing.aspx?id=470773873
maybe a set of new cases could be carved out to suit fitting the chassis better, they could handle a reverse cylinder a bigger disk better crankcase cooling as well as a 6 speed box?

[TZ350]

.... if the engine is moved still a bit further back, you might be able to fit a straigth trombone pipe between cylinder and front wheel. And who cares about front wheel load; that only affects handling...

:laugh: .... yes it does look a tad to far back but funnily enough, at the time some people thought we had it to far forward, I can only describe the chassis as "roomy".

[Frits Overmars]

Pretty silly to jump to an assumption .... certainly the weight bias right or wrong was not left to chance.My silly assumption about engine positions was based on the fact that the weight distribution of the Aprilia RSA turned out to be worse than that of the preceding RSW model because the RSA engine had to be moved further back because of the front-exiting exhaust pipe. So in the top picture the engine already is too far to the rear...

[Brian d marge]

Spend 29 euros on tony foales software

will save u lots of frustration


Stephen

[jasonu]

With the rider in position the weight distribution should be clearly biased towards the front. Judging from the pictures I can hardly imagine this is the case.

That is mostly because of the ( crap (IMO sorry TZ)) chassis they chose to use. Even with extra bracing, better wheels and slicks it is still basically a fancy commuter chassis with plenty of weight and crap geometry. With all the time and effort that has gone into the engine surely a TZ125 or NX4 RS125 chassis is in order. I am sure that once the motor is properly up and running and reliable they will perform a chassisectomy transplant.

[F5 Dave]

262748

heres that photo I said I knew about and have one of a matching sidecar for it aswell
Crumbs, that brings back memories! Been a long time since I've seen it like that. Had its front brake on my H100 for some time. Wonder where that went?

[F5 Dave]

My silly assumption about engine positions was based on the fact that the weight distribution of the Aprilia RSA turned out to be worse than that of the preceding RSW model because the RSA engine had to be moved further back because of the front-exiting exhaust pipe. So in the top picture the engine already is too far to the rear...


None of the rest of us think it was a silly assumption, i think the lads get a bit enthusiastic. But on the other hand, don't those spoked wheels look retro cool?

One of the battles we face placing commuter engines into frames they were never intended for is the sprocket ends up quite far from the sw pivot. It is a compromise but I go for having to deal with running a loose chain & getting the engine as forward as can.

The 250/4 chassis TZ has makes the compromise a step further, but at least it looks more comfortable than me squeezing onto my NF4.


TZ one wonders if you limited the travel on your road set up suspension (that has to deal with pot holes & pillions) the SW variation would be less so you could cope with sprocket distance if you desired.

[bucketracer]

In the picture below, if the engine is moved still a bit further back, you might be able to fit a straigth trombone pipe between cylinder and front wheel. And who cares about front wheel load; that only affects handling...


None of the rest of us think it was a silly assumption,

It was silly to assume Chambers and TeeZee wouldn't have thought about engine position and handling, sure they might not have it right but they would have thought about it.

What offended me was the mocking tone. Would have been better to ask then suggest a suitable ratio.

Any way TeeZee has told me I have "Won" the job of re measuring the Beast.

[F5 Dave]

Please don't offend the world renownd GP expert over internet 'tone', remember he is here by choice

[bucketracer]

Ok ......

262914

A picture speaks a thousand words.

262915 262916

Bike without rider, 48kg front and 48kg rear for 50/50% weight Bias.

262917 262919

Bike with rider, 87kg Front and 104kg Rear for 46% Front 54% Rear.

262918

Engine has to move forward.

Now that begs the question, what is an appropriate weight distribution for a small race bike that doesnt go all that fast?

[F5 Dave]

Perhaps I can answer that question with another;

What pushes the front more?;
- A bike at high lean angles on a Kart track with really tight corners taken at lowish speeds running 4yr old production slicks underinflated to increase temp, or,
- A late 80's RS 125 (to get power closer) on a longer track higher speeds with same tyres but higher pressures?


No, I don't know the answer either.:mellow:


both answers make me want to get the weight forward though.

[husaberg]

Ok ......

262914

A picture speaks a thousand words.

Bike with rider, 87kg Front and 104kg Rear for 46% Front 54% Rear.


Engine has to move forward.

Now that begs the question, what is an appropriate weight distribution for a small race bike that doesnt go all that fast?

I abandoned the NSR frame for the same reason as to get the weight distribution right would entail cutting the spars to do that. Well it is easier to start fresh.

Have you asked Crazy for a replica rs geometry frame quote?
http://images.trademe.co.nz/photoserver/98/207518798_full.jpghttp://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=255797&d=1327297260http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=259933&d=1332029930
But wight distribution is effected by the rider placement as well as he (TZ)is far heavier than the power plant.
TZs frame this is .....The tank is huge and set far back(no doubt most of it was airbox) the subrame looks heavy the clips ons are high.You can lower the forks raise the arse etc.....
but handling is subjective. find some bike with handling you like and replicate it as close as you can.(All of it)

Or put a radiator on it at the front that would help. Maybe a rule change to ballast the 2 strokes will be on the cards:blink:then you can add ballast.

No idea on the best weight distribution but if you reverse yours it will be equal to a 1990 RSV250 Aprilia.
54% front 46% rear Although it was modded later to......no idea what.But as the riders complained at the time about it being too lively under braking.....

[Yow Ling]

Does it have a handling problem or are you guys just inventing one?

Before you go crazy moving the engine why not put 5kg of lead over the front wheel ?

What is the loaded weight distribution for a RS framed bucket ?

[richban]

Does it have a handling problem or are you guys just inventing one?

Before you go crazy moving the engine why not put 5kg of lead over the front wheel ?

What is the loaded weight distribution for a RS framed bucket ?

My bike is 50/50 without rider and 50/50 with rider. I thought I had some sort of chatter problem at the GP. Next race I just leaned forward into a more aero position through the same corner. Fixed. he he.

[richban]

Bike with rider, 87kg Front and 104kg Rear for 46% Front 54% Rear.




That does seam quite a big difference. Is that in a tuck position?

[kel]

Have you asked Crazy for a replica rs geometry frame quote?

TZs frame this is .....The tank is huge and set far back(no doubt most of it was airbox) the subrame looks heavy the clips ons are high.You can lower the forks raise the arse etc.....


Re the crazy frame, I asked, its about a months wages. When you factor in the mortgage, single income, kids etc it works out to be two years savings in real terms. I want one!
Husaberg your comments on the frame are pretty much spot on with my thoughts but as I know next to nothing about chassis set up (cant even set the preload right :facepalm:) then its guaranteed not to be that simple. Before it died last time out we dropped the forks, I was wanting to add preload to lift the rear as well, and that tank well it sure is big and does stop a skinny bugger like me from getting the weight over the front although I think my weight distribution would have more forward bias than the scales test. Dave M was making speedpros bike boogie so the FZR certainly can be riden hard, but then he probably would have disapeared into the distance on an RS chassis.

Seems I've upset people re crazy price (no pun intended). I wasnt stating that its over priced, rather the limitations of my meagre salary and family commitments! Considering the time, effort and quality its extremely good value - note the comment "I want one!" Very sorry, thank you, carry on.

[Henk]

I loved the Crazy frame with Bert's motor in it at Kaitoke. I'd ask him to PM me a rough price but with all the associated RS bits to make it all work I'd probably cry.
Lovely bike to ride though.

[husaberg]

Re the crazy frame, I asked, its about a months wages. When you factor in the mortgage, single income, kids etc it works out to be two years savings in real terms. I want one!
Husaberg your comments on the frame are pretty much spot on with my thoughts but as I know next to nothing about chassis set up (cant even set the preload right :facepalm:) then its guaranteed not to be that simple..I was wanting to add preload to lift the rear as well

Ouch that hurts....:laugh:

One other simplistic idea as well is to add a link to the chain would would be surprised.
One other one was too bring the steering head back with eccentric cups the NSR have huge bearing not sure about the FZR's
But yes they were simplistic but Honda, Yamaha and Suzuki have all made howlers of 500GP bike frames.With huge budgets. these include a YZR500 that was reputedly un-ridable it think it had a coaxel swingarm from memory that one in the mid 90's.So bad it was KR had to go get some ROC frames (that were a copy of the dimensions of the old YZR's) Honda with the upside down bike and well pretty much any four to 1991 ish and Suzuki with the frame 2 inches out for Kevin.Luckily for him they hadn't crushed the old ones and were able to use the old ones.
Yet the euros seem to get it right it is an art but you can paint by numbers as well.
Me well i brought a NF4 frame and forks (Co-incidentally from Crazy)for less than a Weeks wages seeing as the NSR125 and NF4 are reasonably similar. i am confident of not upsetting the handling too much. I would rather have had a NX4 but couldn't find one.Or a crazy frame replica.
I seriously started to make a CF one one but too much time and too hard work and the ancillaries killed the cost.

Oh yeah adding more spring preload actually makes the rear suspension effectively softer BTW.The best handling tip is simple ride the bike lots.

And if i had a Disk valve single, and if i couldn't live with a RS frame couldn't afford a Crazy frame i would probably do a spine frame. or sell a kid?
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=253308&d=1324623497
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=253471&d=1324700308

[speedpro]

The other way I have thought of to get weight forward is to use heavy water in the radiator. There's nothing about it in the rules but "Homeland Security" might ask a few questions.

[Frits Overmars]

It was silly to assume Chambers and TeeZee wouldn't have thought about engine position and handling.It would have been silly of me to assume so. I didn't. People can think about all kind of things but that doesn't mean they will always come up with the right solutions. Judging by the picture I assumed that whoever built the bike had not realized the importance of the weight distribution.
What offended me was the mocking tone. Would have been better to ask then suggest a suitable ratio.You may have a point there, Bucketracer.
Please don't offend the world renownd GP expert over internet 'tone', remember he is here by choiceNo worries, Dave. I can take as good as I can give.
...Bike without rider, 48kg front and 48kg rear for 50/50% weight Bias.Over here, bikes without riders are not allowed on a racetrack. Yeah, there is that mocking tone again. For decades I have seen useless if not downright misleading quotes of rider-less weights, like 'This bike has a one to one power to weight ratio'. It makes me bristle.
...What is an appropriate weight distribution for a small race bike that doesnt go all that fast?I would suggest about 60% front, 40% rear, both for fast and not so fast bikes. If I recall correctly, the latest and fastes Aprilia GP-bike, the RSA250, had 62% front.

[husaberg]

I would suggest about 60% front, 40% rear, both for fast and not so fast bikes. If I recall correctly, the latest and fastest Aprilia GP-bike, the RSA250, had 62% front.
Can you access the figures for the RSA and RSW 125's Frits? As i would suggest the HP would be perhaps more comparative?
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=249819&d=1320056953&thumb=1http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=262959&stc=1&thumb=1&d=1329599156
I would hazard a guess the 125's are a little less front end biased than the 250's?
I had a poke around for the RS125 Honda weight distribution figures but it is not so freely listed.

[bucketracer]

People can think about all kind of things but that doesn't mean they will always come up with the right solutions. Judging by the picture I assumed that whoever built the bike had not realized the importance of the weight distribution.

Yes your right, they did realized its importance and think about it and you can bet TeeZee researched it on the net but they were never confident about what a good weight distribution looked like and tried for what seemed a sensible 50/50.


I would suggest about 60% front, 40% rear, both for fast and not so fast bikes. If I recall correctly, the latest and fastes Aprilia GP-bike, the RSA250, had 62% front.

Well I am blown away by that, we would never have thought 60-62% on the front, thanks for that, its very helpful.

[Frits Overmars]

Can you access the figures for the RSA and RSW 125's Frits? As i would suggest the HP would be perhaps more comparative? I would hazard a guess the 125's are a little less front end biased than the 250's? I had a poke around for the RS125 Honda weight distribution figures but it is not so freely listed.You are no doubt right about the HP, Husa. But alas, momentarily I am in a country far, far away from home and I have no access to my archives.
What you'd need is the RSW's weight distribution because it has been proven to be better than the RSA's. Lots of GP-riders who were 'lucky' enough to get an RSA at their disposal, had great trouble through lack of front end feedback. In fact, the last rider to become world champion on an RSW125, Hungarian Gábor Talmácsi in 2007, declined the offer of an RSA for the second half of the season for that reason.
The Honda RS125 (the latest version, with link rear suspension), though handling better than its predecessor, handles markedly worse than either an RSW or an RSA, according to GP-riders who made the switch. What I do know, is that this Honda's wheelbase, at 1210 mm, is too long for most kart circuits. I don't know about your racetracks, but I assume (a lot of assuming going on today) that they will be (more or less like) kart tracks.

[F5 Dave]

Many of us race on actual Kart tracks. Some race on full size tracks, or rather the short track option of full size tracks. Our GPs tend to be on longer tracks.

[TZ350]

262999 263000

http://www.motorcycle.com/shoot-outs/moriwaki-md250h-vs-aprilia-rs125-shootout-89190.html

An interesting read.

[F5 Dave]

Is it? Why did they even bother comparing a road bike with a race bike? Against a customer 'onda RS125 would have been better. They sort of mentioned it but had no real time, it would have made so much more sense.

[husaberg]

You are no doubt right about the HP, Husa. But alas, momentarily I am in a country far, far away from home and I have no access to my archives.
What you'd need is the RSW's weight distribution because it has been proven to be better than the RSA's. Lots of GP-riders who were 'lucky' enough to get an RSA at their disposal, had great trouble through lack of front end feedback. In fact, the last rider to become world champion on an RSW125, Hungarian Gábor Talmácsi in 2007, declined the offer of an RSA for the second half of the season for that reason.
The Honda RS125 (the latest version, with link rear suspension), though handling better than its predecessor, handles markedly worse than either an RSW or an RSA, according to GP-riders who made the switch. What I do know, is that this Honda's wheelbase, at 1210 mm, is too long for most kart circuits. I don't know about your racetracks, but I assume (a lot of assuming going on today) that they will be (more or less like) kart tracks.

I was being a little checky asking for both.But as i assumed the only difference in the chassis was the weight distribution (i had read on the Pitlane I think thread about the difference in handling) so i was just wondering what the difference in distribution actually was.
I had also read the Aprilia was preferred (esp to the canterlever Nf4) but as Honda love specs statistics and dimensions i thought i might be able to find it easier.
I had seen as production racer model rsr?125 Aprilia once for sale here.
http://raresportbikesforsale.com/wp-content/uploads/2010/05/RSR125LH1-300x225.jpghttp://raresportbikesforsale.com/wp-content/uploads/2010/05/RSR125LHnaked1-300x225.jpghttp://raresportbikesforsale.com/wp-content/uploads/2010/05/RSR125carb-300x225.jpghttp://raresportbikesforsale.com/wp-content/uploads/2010/05/RSR125Dash-300x225.jpg
Not sure on the year 96? or model RSR?but it was about at least 3 times the cost of an equivalent RS125 Honda or like $16000 US. So i would not be hacking one up for a bucket in the near future anyway.
http://raresportbikesforsale.com/1996-aprilia-rsr125-gp-rare/

[quallman1234]

Have weighed my RS, it is pretty much 50/50 maybe a tiny bit front heavy, with a full tank.

[richban]

Is it? Why did they even bother comparing a road bike with a race bike? Against a customer 'onda RS125 would have been better. They sort of mentioned it but had no real time, it would have made so much more sense.

Yeah agree. I remember seeing that ages ago and thought what a waist of time. If they were getting the same hp/liter as we do on the FXR the MD would be well over 42. Maybe 43. But hey its only a 250 MX engine. And the RS is a road bike. What the?

[TZ350]

263007

Got it up on the dyno, did the compression test and then warmed it up, and another comp test, 150 psi, engine warm but not hot. Now I will let it cool right off and then re-tighten the head before giving it a proper run.

263008

My reason for giving it a comp test, I wanted a base line, also EngMod gives a compression pressure figure so I wanted to double check that against my ccing work and our other known engines. I thought 9.7cc for 7.2:1 corrected or 13.7:1 geometric was pretty exacting and I was concerned about measuring it accurately.

[TZ350]

Is it? Why did they even bother ...

I thought the HP figures interesting ...

[Ocean1]

The other way I have thought of to get weight forward is to use heavy water in the radiator. There's nothing about it in the rules but "Homeland Security" might ask a few questions.

Homeland Security's predecessors did have a puzzling interest in an early 70’s French Whitbread Round the World entry.

Eventually transpired it was ballasted with uranium.

[wobbly]

Dont want to sound like im slinging shit at you TeeZee but again I dont understand why you would spec a combustion chamber with a huge squish - 0.8mm when 0.65 is fine.
And no squish width, that gives no squish velocity at all at 18.7M/Sec - this is just throwing away alot of power everywhere in the useable band.???.
As the Ex height has a big influence upon the trapped dynamic com, I use the trapped ratio.
For your air cooled 125 on AvGas a ratio of 7.4 will work reliably no matter where the port is.
Here is the output with the Ex at 82*, double the squish velocity, and near on the same pumping pressure prediction.

[husaberg]

Homeland Security's predecessors did have a puzzling interest in an early 70’s French Whitbread Round the World entry.

Eventually transpired it was ballasted with uranium.

Shame homeland security wasn't more interested in the French crew of the yacht Ouvea.

Oh well they do buy a lot of dairy exports and apples i guess:shutup:

[TZ350]

I dont understand why you would spec a combustion chamber with a huge squish - 0.8mm when 0.65 is fine.
And no squish width, that gives no squish velocity at all at 18.7M/Sec - this is just throwing away a lot of power everywhere in the useable band.???.

True, but its 0.8 static I expect its less at 12,000 rpm, maybe 0.6.


And no squish width, that gives no squish velocity at all at 18.7M/Sec - this is just throwing away a lot of power everywhere in the useable band.???.

The std head has no squish at all, the squish you see is what appears after machining 4mm of the head, not much I know but it is all I have to work with without going to a lot of trouble welding up a head before machining it. Maybe next time.


As the Ex height has a big influence upon the trapped dynamic com, I use the trapped ratio.

Me too, and the head clearance volume changes quit a bit between 82* and 78.5* for the same com ratio.


For your air cooled 125 on AvGas a ratio of 7.4 will work reliably no matter where the port is. Here is the output with the Ex at 82*, double the squish velocity, and near on the same pumping pressure prediction.

That's very interesting.

[TZ350]

263018

The Piranha pipe with the 3ex exhaust opening at 82* ATDC

This is where we got to tonight, not great, just like Wob said, and its cutting off just where it should realy be starting to get going.

But there is an up side, it means that I can raise the main exhaust port to 78.5 where Wob wants it and get a bit of seperation between it and the opening point of the secondries.

263019 263017

Sprung a few leaks in the chamber, working with 0.8mm is just a bit to hard, we need to practice a bit I think. .... :laugh:

[dinamik2t]

But there is an up side, it means that I can raise the main exhaust port to 78.5 where Wob wants it and get a bit of seperation between it and the opening point of the secondries.

I am pretty sure you would lose even more power if you do that with the tripple EX setup.
I would suggest to rise the B,C TFR to 114~115; I believe this will help gain some high RPM power & overrev.

Next of course is the head, which you said it's done for now. To add to Wob's saying -if I can claim to do that-, you don't necessarilly have to use a short squish height. Make a head with a SAR =~45% and there you have your 30+ MSV, while keeping a safe squish height for rod/bearing movements @ high RPM.

Does the pipe has the 23mmD at baffle ending as in Wob's design or does it go directly to the 24.5mm RS stinger? If yes, count a few ponies gone missing from there too.:bye:

Finally, out of curiosity I run my 125cc sim with a dummy 24mm intake to see how it goes. It's 41.5hp, while +3 with the full 38 intake. My timings, if you feel like inspirating, are 81.5 for the main, 84.5 aux, 116/115/115 TFR. And "only" 13* ADV at its peak torque @ 11.8k.

[wobbly]

Squish depth in most 125 engines is safe at 0.65mm in that this means the piston will clip the head at around 14500,its a proven concept.
As you are going nowhere near that rpm there is no reason to run a wider clearance.
Getting good squish velocity induced turbulence in the end gases dictates a lesser need for ignition advance to generate the max combustion pressure.
Less advance = less negative work in compressing the mixture, its all free Hp.
What you have created is a chamber that would work well on a 125 ICC kart engine.
These have fixed advance and will detonate the end gases with close squish and big SARs, but when you have a digital ignition you have the huge advantage of
being able to accurately map the optimum advance to suit the flame speed across the chamber.
As I said, the faster the turbulence induced burn speed, the less timing is needed, for optimum performance.

And yes the pipe design i did was based around using a stinger nozzle.The pipe works very differently without a nozzle,and I would have done something completely different
if just a normal pipe stinger was going to be used.

[richban]

263018

The Piranha pipe with the 3ex exhaust opening at 82* ATDC

This is where we got to tonight, not great, just like Wob said, and its cutting off just where it should realy be starting to get going.

But there is an up side, it means that I can raise the main exhaust port to 78.5 where Wob wants it and get a bit of seperation between it and the opening point of the secondries.

263019 263017

Sprung a few leaks in the chamber, working with 0.8mm is just a bit to hard, we need to practice a bit I think. .... :laugh:

Looks Good Rob. If you can get rid of the dips at the start of the rev rang and the one at the top that looks like a very ridable weapon. Could the one at the top be an main air/jet main jet miss match. Not sure if the PWKs even have an air jet as such but I know that sometimes when you start pushing heaps of air through small carbs the main jet / air jet / bleed can become unbalanced. From what I have read and yet to put into practice. You want to run the main Air/Bleed/Jet the biggest that works. More air better atomization more clean burn more power. So I have been hoping anyway. Could be wrong but Just sharing some ideas that I am trying. Keep up the good work.

Re the bike setup. Something that should be cheap ish and eazy. I would be doing is a 415 chain conversion. No need to push the big chain and heavy sprockets. Should loose a heap of weight out of the rear. Then a new subframe and seat hight might put the rider in a more happy place as Husa has mentioned. The tank is massive for sure but when the seat comes up it won't seam such a beast.

[dinamik2t]

Wob, the highest-possible MSV rule (with min safe squish I mean) applies to all fuel types?
I remember reading a lot of discutions in a respectable 2t forum, concluding that needed MSV is relevant to fuel burn characteristics. and for example in normal unleaded (pump?) gas an MSV > ~30m/s would induce more heat to the engine than do good. Is this obsolete or just wrong ? (kind of the same though)
I am expressing it a little wrong or missing something - hopefully you too have Frits' special guessing ability :sweatdrop

[TZ350]

... get one of these with the extra wire to ground.
When it sees deto it can ground an Ignitech input and retard the timing automatically.

You get flashing lights and engine protection all in one shot, and cheap as chips - made in Czech so it likes being connected to an Ignitech - same lingo.

Works perfectly - when you get it trimmed correctly it will tell you where to manually pull out timing, then it just operates as a failsafe.

http://www.ebay.com/itm/Knock-gauge-for-detonation-sensor-klopfsensor-NEW-/110818862446?pt=Race_Car_Parts&hash=item19cd51a56e&vxp=mtr#ht_1582wt_1297

263028

Ok mine turned up today.

263027

And a couple of two wire sensors I picked up cheap from the local garage.

[2T Institute]

Wob, the highest-possible MSV rule (with min safe squish I mean) applies to all fuel types?
I remember reading a lot of discutions in a respectable 2t forum, concluding that needed MSV is relevant to fuel burn characteristics. and for example in normal unleaded (pump?) gas an MSV > ~30m/s would induce more heat to the engine than do good. Is this obsolete or just wrong ? (kind of the same though)
I am expressing it a little wrong or missing something - hopefully you too have Frits' special guessing ability :sweatdrop

30m/s would be about the minimum you want.

[TZ350]

Looks Good Rob. If you can get rid of the dips at the start of the rev rang and the one at the top that looks like a very rideable weapon.

Rich, thanks for the encouragement, I have found that whenever I try something new I slip back for a bit before getting it sorted. Wobs pipe and engine layout is good for 30+, its my interpretation of it and workmanship that’s let it down, but I will get it sorted.


Could the one at the top be a main air/jet main jet miss match. I know that sometimes when you start pushing heaps of air through small carbs the main jet / air jet / bleed can become unbalanced. You want to run the main Air/Bleed/Jet the biggest that works. More air better atomisation more clean burn more power

Yes I am sure your right a “air/jet main jet miss match” is one of the issues.

Interestingly, it needs the power jet off below 8,000 rpm to get good carburation down low.


Re the bike setup. Something that should be cheap ish and easy. I would be doing is a 415 chain conversion. No need to push the big chain and heavy sprockets. Should loose a heap of weight out of the rear. Then a new subframe and seat hight might put the rider in a more happy place as Husa has mentioned. The tank is massive for sure but when the seat comes up it won't seam such a beast.

There are five GP engines/bikes in the Team ESE stable running 428 chain and sprockets, we already have a big investmint in sprockets and try to keep things interchangeable.

I am pretty sure the Bike was 50/50 with rider on board, maybe it was when the back was jacked up higher than it is now, or it was Chambers bike with the wire wheels we measured, the rear wire wheel on his bike is much lighter than an original FZR one.

I am definitely going to do something about the weight distribution now that I know what a good one looks like.

[richban]

Interestingly, it needs the power jet off below 8,000 rpm to get good carburation down low.



Hummm. Maybe the power jet jet is to big. Is it working to early? Main to big with power jet on maybe. Anyway look forward to seeing it out on track again.

[dinamik2t]

Good luck with the Deto sensing TZ. I like the little warning instrument!

Here's how I mounted my sensor. I drilled-tapped an old head bolt and screwed a stud.

263051263052

My sensor has a PN 0-261-231-001, what's yours?
According to this http://www.phormula.co.uk/KnockCalculator.aspx , deto freq for 56mm bore should be 10.2kHz.
According to Bosch datasheets for PN -047 (http://www.bosch-motorsport.de/en-US/literature/en-US/Knock_Sensor_KS-R_Datasheet_51_en_2779074187.pdf) & -120 (http://www.bosch-motorsport.de/pdf/sensors/knock/KS-P.pdf), sensors are able to catch frequencies from 1 to 20 kHz.
I assume all Bosch sensors can sense knock within this range (?)

edit: As for the pick-up voltage, I think it won't be more than +-10V. I had a voltage test yesterday with a data acquisition device in real time! I spinned the crank by hand and recorder the voltage waveform from the pick-up in the PC. As RPM increase, amplitude (and freq of course) of the pulses increase - by hand-spinning it didn't exceed 3~3.5 VAC. Sure it was a lot of fun to watch! :D

[TZ350]

Hummm. Maybe the power jet jet is to big. Is it working to early? Main to big with power jet on maybe. Anyway look forward to seeing it out on track again.

Yes I enjoyed seeing you guys at Kaitoke, it was a brilliant weekend.

With no power jet at all the top falls off earlier with less over rev. I think it just comes on to early and I can use the Ignitec to fix that.

[TZ350]

Good luck with the Deto sensing TZ. I like the little warning instrument!

Here's how I mounted my sensor. I drilled-tapped an old head bolt and screwed a stud.


Thanks for the pics and tips. To be honest I am not sure what the the pickup has to do with it, at the moment I dont understand it at all.

I will look for any numbers on my pickups, could you please tell me more about how the whole thing goes together.

[richban]

I think it just comes on to early and I can use the Ignitec to fix that..

Fancy. Spoze you want it to start working a just past 3/4 throttle almost full.
I was just watching a video of Kaitoki. Good fun.

[dinamik2t]

I don't know either why pick-up voltage would be required.:scratch:
Perhaps it has something to do with the amperage limit of the output wire?

[TZ350]

I was just watching a video of Kaitoki. Good fun.

We will be back ..... :msn-wink:

[TZ350]

Taper Bored 24mm OKO, its 24mm at the very front, 29mm at the slide and 31mm at the manifold end.

263055 263056 263057

In the middle picture you can clearly see the air correction jet, its just a drilling in the carb body. It was about 0.8mm and I have opened it to 1.45 but after reading Riches post I will try bigger.

263054

Posted because someone asked me where the Power Jet is positioned on my carb.

263073

My plan is to use an electric air solenoid (purchased from JayCar) to bleed air into the powerjet to interrupt its function below 7,000 rpm or so.

[husaberg]

Taper Bored 24mm OKO, its 24mm at the very front, 29mm at the slide and 31mm at the manifold end.

263055 263056 263057

In the middle picture you can clearly see the air correction jet, its just a drilling in the carb body. It was about 0.8mm and I have opened it to 1.45 but after reading Riches post I will try bigger.

263054 Posted because someone asked me where the Power Jet is positioned on my carb.

My plan is to use an electric air solenoid to bleed air into the powerjet to interrupt its function below 7,000 rpm or so.

I will try to keep this post small i will trim it down a bit later and put it more in an order etc.

When using a simple powerjet nozzle the tip position matters in that no flow will occur until the slide is well past the exit hole, and there is sufficient airflow
to drag fuel up the feed tube above the bowl level.
With the aftermarket add ons and the ones as used by Lectron you can shorten the dump tube so that the flow will only occur at high slide openings,as well as high air flow.
These also have a built in "lag "control in that it takes time for the fuel to rise up the tube and dump out the exit into the air stream.
With a solenoid controlled setup all this is pretty much irrelevant as the flow can only occur when the solenoid is not powered up, and this
is TPS as well as rpm dependant inside the ECU program..
The carbs as used on the MX bikes has the dump tube very low in the bore as they added and subtracted fuel at low slide positions in those bikes.
For a race engine I bend the tube up to around 1/2 bore, as this is where the exit is on the Kehin SPJ carb for RS125/RS250 Honda.
And the general setting is the solenoid is powered up ie no flow below 4000 and 60% TPS and is powered up again at around 12400 to lean off the mixture and increase revon.
This causes a problem with Ignitechs that are used with only a capacitor, as at startup the solenoid is powered up, dragging all the voltage out of the ECU, so I convert the ECU output
to a 3 step truth table, and have the setting such that below 1500rpm the solenoid isnt powered.


Aha, I see. I think I got it now, Frits.
If the powerjet is positioned in the middle of the venturi or at a lower point, that will affect how much it will flow, correct?

I remember both Lectron and Mikuni aftermarket PJ kits' instructions, saying that the end tip of the pj should be around the middle of the carb.
Yet the Keihin PJ of the carbs for the mx250 models is down low! Position would also affect which fraction of the flow becomes more rich or not, or that doesn't matter??

255006


Nope. It is drawn by the dynamic pressure at the fuel exit points in the carburetter. And that pressure depends on the mean air flow velocity along those exits.
Air flow velocity is at its highest in the center of the narrowest part of the inlet tract, so the location of the fuel exit will make a difference. And by mean air flow I mean (air flow into the engine + backflow)/2.
You see, more than enough variables; more than enough differences between the exit points of the fuel flow through the main jet and the flow through the power jet.

254941

Made an adjustable PJ out of a model aero engine carb needle jet for controlling the PJ. Now to get one of those solenoids the Husaburg posted to shut off the PJ for a bit of extra over rev.

Made some progress with the shorter inlet tract and expect to get the lower mid range back again with a bit of fiddling with the carburation.

Just a little bit more and the single exhaust port engine with the RS pipe will be very close to EngMod2T's predicted power output.

254940 125cc rotary valve with a 24mm carb and air cooled.

Measured 31 rwhp (estimated 34 crank hp) on the dyno tonight, red line is last night before the inlet tract was shortened and the jetting/ignition adjusted.

I have ordered one of Wobblys special kitset "A" Kit Pipes for a Suzuki GP125 ..... so hopefully 1 or 2 more hp and a wider spread of power. Then there is the ATAC idea for better low end.



Re the tiny bleed hole in the TZ powerjet tube - I always thought that this was a good idea to emulsify the fuel as it exited the dropper.
But years ago i did some wet tests on the flowbench with a VCR video camera ( pretty trick shit stuff back then ).
The Mikuni was a horror scene when played back slo mo,with huge "gobbs" of fuel exiting the main and powerjet.
We then stuck on a Lectron - wow, lovely fine mist of fuel from the back of the flat needle face - and it flowed 12% more air - size for size with a venturi 2mm smaller behind the slide.

Next is the current state of TeeZees GP125, here is the latest dyno curve digitised with 16% added to simulate crank power.
Then there is the sim with an actual RS early model pipe.
Then there is the new pipe of my design.
Of most interest is that in this case the sim is giving slightly too much crank power - but the shape and peak point are all but perfect.
I would be confident now that any change in the sim, would be reflected in reality on the dyno.
In my experience the later Dynojets like a twin roller 168 with Eddy current load control to slow the acceleration rate down ,seem to read around 5 to 10% lower
so this would put the sim and the dyno reading very close, as the shape is spot on now.


You have to be very carefull with the switch point and the run time on the dyno.
The switch point is dead critical to 100rpm,so i always set it too high initially and make sure that the dyno is loading the acceleration rate to be as close to that on track as you can.
This gives the pipe time to heat up and affect the power over the top, as it would in reality.
On a RS250 dropping the switch point from 12800 ( std) to 12400 gives easily another 800 rpm of virtually no power drop past peak.
On the track,if the rider can feel the switch point ( it feels like hooking another gear)the jet is too big,when its right it should be seamless and just keep reving out.
Leaded fuel is the opposite to unleaded, in that as leaded likes to run lean - you can only use a small powerjet and thus only switch off a small amount.
A leaded engine works best with around 35 to 38 PJ, the unleaded fuel can switch a 60, in Keihin numbering, as the crap fuel makes best power at peak when quite rich..


And something that I scraped from the net.........

""The solenoid control on TZ type powerjets really just shuts off fuel flow to the powerjets right at the top of the rev range to lean the mixture off to increase the over-rev once you are past peak power.

I don't have the solenoids plugged in currently though as I find they work well enough for my current needs with the powerjets simply responding to venturi vacuum pressure in pretty much the same way as the oem 3MA powerjets work.""

233787233788

And here is a picture of the carbs and what I can make out, a dyno graph without, and with the power jet solenoids shutting off (red line) and extending the over rev.

So it looks like you can use an electric power jet like a standard one and when the carburation is sorted, try switching it of by activating the solenoid at or just after peak power and see what happens with the over rev.


The FPE superkart engine that won the NZ road title at Manfield a few weeks ago makes 92 RWHp on the Dynojet 168 I use.
Still not quite as good as the RS250 setup we did that won at Laguna Superkart Worlds a couple of years ago.

The powerjet carb is controlled by the Ignitech with a combination of throttle position and rpm in a "truth table".
In general the solenoid is activated with 12V ( no fuel flowing) below 4000 rpm and 75% throttle on the TPS.
Above 75% and around 12400 rpm it is activated again to lean off the fuel curve over the top of the pipe.
Looks like you will be able to reverse the fuel exit, blocking off the hole on the throttle bore side, and take off fuel from the outside bung, thru a needle jet and into the top of the venturi next to the slide.


Recently I got myself (Ebay) a 38mm carb with Throttle PS and Electric PJ from a motor crosser.

Wobbly told me that on those the PJ nozzel is to low and starts to flow to soon for a road racer and the MX ones are hard to tune.

230481

I couldn't afford to buy a good second hand TZ or RS unit. So I figure that moving the discharge nozzel.

230483

And adding an adjustable jet from a large model aero engine could be worth a try.

230482

On the dyno I have seen how a leaner mixture rev's on further and how richining it up for best power the over rev drops off.

I think that as the rpm goes up the mixture strength on an ordanery carb at max rpm goes over rich.

And at the moment I think the idea is that the PV is shutoff after peak power to get back to the correct mixture and by retarding the ignition at the same time extend the over rev, but I am sure there is more to it.

I would love to know more about how this type of carb should be used and/or setup.



The modern take on powerjets is to turn them off after peak power to extend the rev range. This assumes that you are happy for your engine to rev that much further past peak power & on many buckets perhaps this is not so good unless you have uprated the crank assembly. The jet will start to flow, depending on its position. Some don't seem to work well without an airbox if they aren't very prominant, or perhaps if the suction isn't so much (putting big carb on a smaller cylinder). In some cases they are best blocked off presumably if the air jet doesn't match very well & is tending to increasing richening with airflow as it is.


With all the talk about wanting to utilize only a couple of gear changes per lap, I would have thought that the solenoid powerjet was a gift from heaven.
A late model well tuned RS125 will rev to around 12400 if the PJ is disabled,turn the PJ function back on and it will go to 13800+.
Its so simple and you retain exactly the same lower rev power,but with easily another 1000rpm to work with you have the choice of adding teeth on the back, getting better acceleration from torque multiplication, or keeping the same gears - but increasing the terminal speed.
And from the dyno curves I have seen, most of the 100 buckets with short stroke lengths, arent even beginning to stress the bottom ends - with less peak rpm than the 54.5mm stroke 125 bikes or karts that will easily run to 13000 all day.



Some more RSA125 development info from Jan Thiel

"No pressure transducers were ever used in our engine development.
And time/aerea was never calculated.
The port timings remained practically the same during 15 years!
What we did was trying different angles and radiuses, mainly on
the transfer ducts. I think we tried 40 different types of transfer ducts
that did not chanche the time/aerea. It was all about in which direction
the charge entered the cilinder and how the tranfer streams influenced upon
each other! Also about 200 different exhaust pipes were tried. After 2004
nothing much was changed but we improved with different power jet and
ignition mapping. It seemed nearly impossible to improve the transfer ducts
any more. The exhaust ducts were CNC machined, using different programs,
mainly to reduce exhaust duct volume. Also about 100 head designs were tried"

Didnt calculate time area? Im guessing that means the time area requirement hasnt changed any in the last 15+ years.
So there you go its all about the transfer ducts, now where have I heard that before?
Check out the attached photos, I guess the idea of thinning the transfer duct bridge has gone out the window, and the exhaust duct hows that for a crazy shape


231454
231455
231456


Recently I got myself (Ebay) a 38mm carb with Throttle PS and Electric PJ from a motor crosser.

Wobbly told me that on those the PJ nozzel is to low and starts to flow to soon for a road racer and the MX ones are hard to tune.

230481

I couldn't afford to buy a good second hand TZ or RS unit. So I figure that moving the discharge nozzel.

230483

And adding an adjustable jet from a large model aero engine could be worth a try.

230482

On the dyno I have seen how a leaner mixture rev's on further and how richining it up for best power the over rev drops off.

I think that as the rpm goes up the mixture strength on an ordanery carb at max rpm goes over rich.

And at the moment I think the idea is that the PV is shutoff after peak power to get back to the correct mixture and by retarding the ignition at the same time extend the over rev, but I am sure there is more to it.

I would love to know more about how this type of carb should be used and/or setup.


Ok now we have a stepper motor controled power jet........

The 'high compression brickwall' is no longer as hard as it used to be. With leaded fuel the compression ratio was 19,5; nowadays it is about 15. The 'brickwall' arose from the high expansion ratio (which is identical to the compression ratio). The higher this ratio, the more the burnt gases in the cylinder cool down before they enter the exhaust, thus lowering the resonance frequency of the exhaust system.
Riders complained that the engine would not rev, especially not in the lower gears, where the revs rose so quickly that the rising wall temperature of the exhaust pipes could not keep up with them. So you had cold exhaust gas and cold pipes.

The problem was to a large extent solved when the solenoid-controlled on/off-power jets were replaced with stepper motor-controlled jets that could continuously adjust mixture strenght, allowing the engine to rev more freely.

229455

This is it. The stepper motor itself originates from a Fiat Uno where it regulates the idling rpm

Regarding the Aprilia RSW/RSA125 single, Jan Thiel told me that in seven years of testing the racing department had not been able to establish which was best: low or high inertia. I would choose low.....

Frits Overmars

[husaberg]

I am a bit stuck with the timings as I cut the secondry exhaust ports a bit big. It was my first effort and more about seeing if it could actually be done.

At 116 the front transfers come very close to the underside of the side exhaust ports so I cant move any more there and the rear transfers need to open a little later than the fronts, so its all a bit compromised really.

I originaly wanted to make a broad spread of power but have allowed myself to get distracted by the side show of building a racing Bucket engine that reliably makes over 30hp and my tripple port is aimed at that.

262591 262592

50hp 125 Aprilia racing engine.

Side Ex boost ports are the way to go to get the blow down STA needed to make real power and to allow a smaller width main exhaust port for piston/ring reliability.



In all fairness, there are other people in the Tuning Industry that have their own ideas about the worth of Ex boost ports for racing .....

262570 262571

I think they are the Bizz but don't like wasting good cylinders on experiments, so I used an old damaged cylinder to see if it was actually possible to cut these side ports, turned out OK but not to sure about racing reliability. Although the main exhaust port is not as big as the 31hp cylinder that failed at Kaitoke so that must help.

Should be interesting on the dyno ....... and if its any good then we will see if it holds together on the track.

Found these other pics of the Aprilia on the thread EX ports.


Some more RSA125 development info from Jan Thiel

"No pressure transducers were ever used in our engine development.
And time/aerea was never calculated.
The port timings remained practically the same during 15 years!
What we did was trying different angles and radiuses, mainly on
the transfer ducts. I think we tried 40 different types of transfer ducts
that did not chanche the time/aerea. It was all about in which direction
the charge entered the cilinder and how the tranfer streams influenced upon
each other! Also about 200 different exhaust pipes were tried. After 2004
nothing much was changed but we improved with different power jet and
ignition mapping. It seemed nearly impossible to improve the transfer ducts
any more. The exhaust ducts were CNC machined, using different programs,
mainly to reduce exhaust duct volume. Also about 100 head designs were tried"

Didnt calculate time area? Im guessing that means the time area requirement hasnt changed any in the last 15+ years.
So there you go its all about the transfer ducts, now where have I heard that before?
Check out the attached photos, I guess the idea of thinning the transfer duct bridge has gone out the window, and the exhaust duct hows that for a crazy shape


231454
231455
231456
AND a Honda EX

No not planning anything too radical.

228854228855

Wobbly was just explaining to me the lengths the rotary valve boys are going too, to compete with the reed valvers and how it might be hard to get a big enough inlet port on our GP's with their smallish side rotary valves.

228856

Yum yum stuff........ head inserts and an electric power jet carb with a throttle position sensor.
228857

Real transfer ports ..........

[SwePatrick]

I´m having a wonder here..

Why not restrict the airflow where there´s no fuel blended in into the airmass.
Then you can choose an.. say 36mm carb and build a big plenum on the carb with an perfect lavalnozzle at 24mm?

Take a look at Formula 3 cars.
They have an HUGE plenum with a tiny restrictor, inside the plenum theres an long diverging kone to stack upp the air again.

Or are you restricted by rules that carb MUST be 24mm?

pics:
http://www.blogcdn.com/www.autoblog.com/media/2007/12/fpv-420f3.jpg
http://upload.wikimedia.org/wikipedia/commons/thumb/1/1d/De_laval_nozzle.svg/800px-De_laval_nozzle.svg.png
http://formula.tamk.fi/wp-content/gallery/fs011-building/221040_10150173308568559_786138558_6712850_1562970 _o.jpg

By looking at your modded Koso carb i think it might be worth a test, but it might be a problematic one to jet correct.
(A cone like this you lathed is to be at 7degrees+-1.)
Why jettingproblems?
because you got the highest airspeed at the very front of the carb, not at the point where you want it,, at the venturi where the needle is located.
You just might 'choke' the airflow at the front of carb.

Rgds
Patrick

[TZ350]

Interesting pictures and ideas, maybe the thing would be to use your idea and direct injection into the cylinder like Orbital does ...


Or are you restricted by rules that carb MUST be 24mm?


Yes my carb must be 24mm.

263074

The other restrictions are, what we can achieve with Mr Rattly, the old lathe

263084 263085

and basic hand tools.

[wobbly]

I would lift the main port to 80* then lift the B & C ports to around 114.5 or so.
You have the perfect tool to see if the STAs are in the ballpark - run it thru EngMod and see what happens.
Means you have a setup that mirrors the Aprilia design philosophy.

[TZ350]

My sensor has a PN 0-261-231-001, what's yours?
According to this http://www.phormula.co.uk/KnockCalculator.aspx , deto freq for 56mm bore should be 10.2kHz.

263081

BOSCH p/n 0 261 231 046

263082

Other sensors can be found here too. http://www.bosch.com.au/content/language1/html/4563.htm

[husaberg]

I´m having a wonder here..

Why not restrict the airflow where there´s no fuel blended in into the airmass.
Then you can choose an.. say 36mm carb and build a big plenum on the carb with an perfect lavalnozzle at 24mm?


because you got the highest airspeed at the very front of the carb, not at the point where you want it,, at the venturi where the needle is located.
You just might 'choke' the airflow at the front of carb.

Rgds
Patrick

Frits has mentioned this at some stage. The idea being only the airflow was restricted before the additional mass of the fuel mixed in with it if i recall correctly.

Found it thread tools rock. I knew Frits would have a picture.


256967

This is what my ventori tube looks like, flow is from left to right, two ramps, leading ramp is 34 deg included and trailing ramp is 14 deg included angle.

Could the flow be improved by making the leading edge ramp into an aero foil shape like the leading edge of an aeroplane wing as in your picture.

It would certainly shorten up the tube and get the venturi point closer in behind the slide.



Yes, make it into a bellmouth. That will get you both a shorter unit and a better inflow. You might also consider putting the restriction in the bellmouth if your rules allow it. That would mean you can have a considerably longer trailing ramp (the widening can start right after the bellmouth, i.e. under the throttle slide). It also means that only the air, not the fuel, has to pass through the restriction. That way the total mass that has to be accelerated through the restriction, will be about 8 % less.
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=257001&d=1328626099
Still a good idea though.

[bucketracer]

Taper Bored 24mm OKO, its 24mm at the very front, 29mm at the slide and 31mm at the manifold end.

263056 263057 263054


TeeZees carb has the 24mm restriction ahead of the slide so only air passes through it and I think he was actually testing it before Frits suggested it. But in reality on TeeZees engine there is a fare bit of fog when its making max power so its probably a moot point. This is the carb he used on his 31rwhp setup.

The answer to the, three times past the main jet fog at max power question suggested by Frits, was that the fog may indicate the inlet stream is bouncing off the closing disk and that it may be possible to shut the inlet a little later.

[F5 Dave]

ok, a question for the panel;
Small end bearing axial (to piston) clearance; How much is too much? Obviously if the bearing can travel far enough so the rollers touch the edge of the rod they will grab on the sharp end & lock immediately causing mondo destruction. I found this out the hard way running RD50 pistons in my MB50 20 years ago, they needed thrust washers in that application.


The MB pistons (in the 50 as the 100, which is what I'm now talking about, the 100) are bevelled at the piston pin bosses. They leave a scant .4mm clearance at the top & ~4mm at the bottom, which is obviously nice for lubrication. Yamaha KT pistons are straight edged at the bosses.

The OEM stuff I have measured for small pistons seems to run 1mm clearance, so .5 per side. 250cc cylinders run up to almost 2mm it seems.

So I'm left with the suitability question over 17mm wide MB SE bearing in a Yam piston with 19.2mm between the bosses, so 2.2mm clearance. With a wider rod it should not make it out of the small end.

I'm not overly happy with the 2.5mm rollers (making for a 14x19 bearing) that only has 11 rollers, but they seem to go ok in std bikes. Most of the 18x14 brgs seem to run 12 rollers.

[wobbly]

I had a quick look at the 3Ex GP125 in Engmod.
Lifting the main Ex to 80* needs to have the B,C transfers lifted to 113.8* to get the STA near balanced again.
It will then have staggered Ex plus reverse staggered transfers,Mr Thiel would be proud.

[TZ350]

I had a quick look at the 3Ex GP125 in Engmod.
Lifting the main Ex to 80* needs to have the B,C transfers lifted to 113.8* to get the STA near balanced again.
It will then have staggered Ex plus reverse staggered transfers,Mr Thiel would be proud.

That looks good Wob, it will take me a few nights next week to get it sorted then we can give it a spin up.

[TZ350]

I was recently asked about servos for the Ignitec and if I thought a Radio Control servo could be used for the exhaust power valve.

Well I don't think so, or at least not easily or without a bit of work, and they are only 3 to 5V or so too.

My understanding is that a normal power valve servo is a motor and feedback potentiometer. And how it works is that the Ignitec is shown where the fully open and fully closed points are, ie 100% travel. Then the Ignitec can position the power valve anywhere from 0% closed to 100% open using the feed back potentiometer.

A RC servo works the same internally but is controlled by a variable input frequency transmitted from the pilots radio hand set. As the pilot wiggles a knob the frequency of that knobs channel changes a little bit and that tells a little chip inside the RC servo the changes to make.

263116

RC Servo

263114

An RC Servo Tester mimicks the pilots handset, you turn the knob on the tester to vary the frequency being sent to the RC servo and hence its position.

263115

The change in frequency is interpreted by the chip inside the RC servo.

And the chip positions the servo motor using an internal feedback potentiometer just like the Ignitec does with a power valve servo.

263117

I was able to use a RC servo to open/close the Vtec Valve by using two RC Servo testers, one set to open, the other to closed and a Relay that the Ignitec activated when it was time to open the Vtec.

It may be possible to cut into a RC servo and bypass its internal electronics and modify it to work like a normal power valve servo.

This link may show more: http://www.societyofrobots.com/actuators_servos.shtml

If anyone manages to modify a high torque RC servo to work as an ordinary power valve servo, it would be great to have the details posted here.

[husaberg]

I was recently asked about servos for the Ignitec and if I thought a Radio Control servo could be used for the exhaust power valve.

Well I don't think so, or at least not easily or without a bit of work, and they are only 3 to 5V or so too.


263117

I was able to use a RC servo to open/close the Vtec Valve by using two RC Servo testers, one set to open, the other to closed and a Relay that the Ignitec activated when it was time to open the Vtec.

It may be possible to cut into a RC servo and bypass its internal electronics and modify it to work like a normal power valve servo.

This link may show more: http://www.societyofrobots.com/actuators_servos.shtml

If anyone manages to modify a high torque RC servo to work as an ordinary power valve servo, it would be great to have the details posted here.


Are they any cheaper than say a RI servo Rob? I would have thought they (The R1 servo)were err..almost Taylor made for this sort of applications.
Wob wants me to buy one but as i already have an RZ one i am loathe to shell out for one. He warned me they after sitting arround wouldn't last though.
OK so i read a thread the other day were someone (On a Bucket) did the same and guess what just as Wob suggested the old RZ servo soon gave up the ghost.
I guess Wob may have learnt that one the hard way as well.
From what understand the R1 servo is a direct replacement for an RZ is that right? (Not that i am that happy about sullying Honda with Yam parts mind you):shit:

[TZ350]

I had always been a little wary of running the RC servo for the Vtec Valve inside the plenum because of the explosive fuel vapor.

http://www.societyofrobots.com/actuators_waterproof_servo.shtml

But this article on water proofing a servo by filling it with oil would also work to make it explosion proof.

[TZ350]

Are they any cheaper than say a RI servo Rob? I would have thought they (The R1 srvo)were almost Taylor made for htis sort of applications. From what understand the R1 servo is a direct replacement for an RZ is that right?

Yes the person who asked was having reliability issues, I don't know if they had tried an R1 unit though. I was not promoting the RC servo as a solution, just replying to an interesting question. Me, for a power valve I would try Wobblys R1 suggestion and play with converting a RC servo only if I got bored.

[Bert]

I was recently asked about servos for the Ignitec and if I thought a Radio Control servo could be used for the exhaust power valve.

Well I don't think so, or at least not easily or without a bit of work, and they are only 3 to 5V or so too.

If anyone manages to modify a high torque RC servo to work as an ordinary power valve servo, it would be great to have the details posted here.


Yes the person who asked was having reliability issues, I don't know if they had tried an R1 unit though. I was not promoting the RC servo as a solution, just replying to an interesting question. Me, for a power valve I would try Wobblys R1 suggestion and play with converting a RC servo only if I got bored cutting my fingers off.

Interesting things these High torque RC servos.. many of them contain metal gears; which would be a great improvement over some Exhaust servos that I've pulled apart...
Thanks for posting up further interesting information.

[TZ350]

... front wheel load; affects handling ... horsepower can gain you tenths of seconds and handling will give you whole seconds?

Improving the handling by moving the engine forward to put more weight on the front wheel.

263175

Its hard to see what can be done. There is already quite a distance between the front sprocket and swing arm pivot, and it doesnt look wise to increase it.

On the dyno under power this bike has a definit squat, is that good or bad? does it unload the front wheel in a corner? this bike does suffer from front end chatter when pushed hard.

Maybe shortining the frame rails to bring the front wheel back to the engine is a possibility and fitting a lighter sub frame and rear wheel like Bert suggested.

Yes, improving the handling is something we are very interested in.

[teriks]

I was recently asked about servos for the Ignitec and if I thought a Radio Control servo could be used for the exhaust power valve.

Well I don't think so, or at least not easily or without a bit of work, and they are only 3 to 5V or so too.
If you have a good DC-source, a BEC for ~20US$ could solve the voltage problem:
Example: http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXSWL3&P=ML


This is the CC BEC 10A Receiver Battery Eliminator by Castle Creations.

FEATURES: Eliminates the need for a receiver and servo battery pack Draws higher voltage from the motor batteries and drops it to a voltage level suitable for the receiver and servos

SPECS:
Length: 1.2" (30mm)
Width: .6" (15mm)
Height: .4" (10mm)
Weight: .4oz (11g)
Input voltage: 5V to 25.2V (2S to 6S LiPo)
Current output: 12 volts input = 7 amps* continuous, 10 amp peak; 24 volts input = 5 amps* continuous, 7 amp peak
*Ratings are determined with a 5mph airflow on the BEC
Selectable Output: 4.8 - 9.0V via the Castle Link (sold separately) Default voltage is 5.1V



It may be possible to cut into a RC servo and bypass its internal electronics and modify it to work like a normal power valve servo.

A decent RC servo is surprisingly fast and accurate, IMO it would be nice if you are able to provide a pulse train and let the servo electronics do it's stuff.
Could be a decent product for ignitech to develop, might be worth asking?
RC servo control info: http://www.mitchr.me/SS/batteriesRequired/RCcontrolTheory/index.html

[husaberg]

Improving the handling by moving the engine forward to put more weight on the front wheel.

263175

Its hard to see what can be done. There is already quite a distance between the front sprocket and swing arm pivot, and it doesnt look wise to increase it.

On the dyno under power this bike has a definit squat, is that good or bad? does it unload the front wheel in a corner? this bike does suffer from front end chatter when pushed hard.

Maybe shortining the frame rails to bring the front wheel back to the engine is a possibility and fitting a lighter sub frame and rear wheel like Bert suggested.

Yes, improving the handling is something we are very interested in.
Depends on how far you wish to go really.
The steering head doesn't look that steep with your current set up either the steering head can be brought back fairly easily as well. Assuming the steering head bearings can be made smaller OD so you can use an eccentric cup or cups without major changes.
The weight bias can be improves with the engine tilted forward.
but the problem you have is it was designed for a 4 stroke 4 with a engine (four stroke leaning forward at 45 degrees or so.(Oh it is wide too as well with kinks in the spars too)
If it was me i would bite the bullet make a jig with the specs you want (say NX4 based) and make the frame fit that.
oh yeah put a fairing on the front that will help too.

Or just weld another steering head into the frame you have now wow there is ample room by the look of it.

But by the time you did all this it would have been far far easier to make a spine frame to the required dimensions.
You may have a drive shaft the right size laying about somewhere and a suitable donor frame for the steering head.
You know you want to TZ.

[richban]

Improving the handling by moving the engine forward to put more weight on the front wheel.

263175

Its hard to see what can be done. There is already quite a distance between the front sprocket and swing arm pivot, and it doesnt look wise to increase it.

On the dyno under power this bike has a definit squat, is that good or bad? does it unload the front wheel in a corner? this bike does suffer from front end chatter when pushed hard.

Maybe shortining the frame rails to bring the front wheel back to the engine is a possibility and fitting a lighter sub frame and rear wheel like Bert suggested.

Yes, improving the handling is something we are very interested in.

From what the scales say the bike sits 50/50 without a rider. Personally I think that is fine. Don't move the engine. All your problems start when you put the jockey in position. So all you need to do is change the riding position to something that works. Sub frame for sure coz that will give you a weight saving no matter what. lifting the seat hight so the rider can get a little more on top of that tank. As I mentioned before. I had front end chatter at the GP. I was just being lazy in a bad body position. I changed that and the bike was clued. When we were looking at my bike on the scales I could alter the front end load with body position by 4ish kg. Question is do you go for a setup that locks the rider in to the correct setup or one that allows more movement.

[richban]

Depends on how far you wish to go really.
The steering head doesn't look that steep with your current set up either the steering head cant be brought back fairly easily as well assuming the steering head bearings can be made smaller OD so you can use an eccentric cup or cups without major changes.
The weight bias can be improves with the engine tilted forward.
but the problem you have is it was designed for a 4 stroke 4 with a engine (four stroke leaning forward at 45 fdegrees or so.
If it was me i would bite the bullet make a jig with the specs you want (say NX4 based) and make the frame fit that.
oh yeah put a fairing on the front that will help too.

Or just weld another steering head into the frame you have now wow there is ample room by the look of it.

But by the time you did all this it would have been far far easier to make a spine frame to the required dimensions you know you want to TZ.
You must have a drive shaft the right size laying about somewhere and a suitable donor frame for the steering head.

Yeah true that. The engine it used to have must have weighed in around 50kg. I am sure you can make some major improvements easy.

[wobbly]

I have had at least 5 of the old RZ servos die on me - they are just too old now.
The R1 EXUP servo is cheap ( I have a box full of them off Ebay ) and all but a direct replacement - bar the female plug is part of the body.
Get the male plug with some lead on it or I have plenty of plugs here.

Squat is complete shite on a racebike,drop the rear of the motor as far as you can, the chain will rub on the swingarm in the static positiion.
Lowering the sprocket creates anti squat, so as you wind in the power, the rear rises and loads up the front, stopping chatter.
Worst place for this is the sweeper onto the straight at Hampton.

[richban]

Worst place for this is the sweeper onto the straight at Hampton.

Or Pothole at Ruapuna.

[husaberg]

Yeah true that. The engine it used to have must have weighed in around 50kg. I am sure you can make some major improvements easy.


There was a reason i choose a MC16 frame for a start off it had pretty straight rails and i believe it was the narrowest Honda NSR frame.
As it was made for a V-twin it was also a great deal narrower than a 4 cylinder one.
These below are the dimensions for a NSR250 one the MC16 should be similar it might be a better starting point failing that i guess the swingarm, forks etc might slot in a TZR frame.
But like i said it would be easier i reckon to make your own. You have the technology and the facilities. You have access to a NX4 frame as well too.

[F5 Dave]

Bump? .

ok, a question for the panel;
Small end bearing axial (to piston) clearance; How much is too much? Obviously if the bearing can travel far enough so the rollers touch the edge of the rod they will grab on the sharp end & lock immediately causing mondo destruction. I found this out the hard way running RD50 pistons in my MB50 20 years ago, they needed thrust washers in that application.


The MB pistons (in the 50 as the 100, which is what I'm now talking about, the 100) are bevelled at the piston pin bosses. They leave a scant .4mm clearance at the top & ~4mm at the bottom, which is obviously nice for lubrication. Yamaha KT pistons are straight edged at the bosses.

The OEM stuff I have measured for small pistons seems to run 1mm clearance, so .5 per side. 250cc cylinders run up to almost 2mm it seems.

So I'm left with the suitability question over 17mm wide MB SE bearing in a Yam piston with 19.2mm between the bosses, so 2.2mm clearance. With a wider rod it should not make it out of the small end.

I'm not overly happy with the 2.5mm rollers (making for a 14x19 bearing) that only has 11 rollers, but they seem to go ok in std bikes. Most of the 18x14 brgs seem to run 12 rollers.

[husaberg]

Bump? .

ok, a question for the panel;
Small end bearing axial (to piston) clearance; How much is too much? Obviously if the bearing can travel far enough so the rollers touch the edge of the rod they will grab on the sharp end & lock immediately causing mondo destruction. I found this out the hard way running RD50 pistons in my MB50 20 years ago, they needed thrust washers in that application.


The MB pistons (in the 50 as the 100, which is what I'm now talking about, the 100) are bevelled at the piston pin bosses. They leave a scant .4mm clearance at the top & ~4mm at the bottom, which is obviously nice for lubrication. Yamaha KT pistons are straight edged at the bosses.
The OEM stuff I have measured for small pistons seems to run 1mm clearance, so .5 per side. 250cc cylinders run up to almost 2mm it seems.
So I'm left with the suitability question over 17mm wide MB SE bearing in a Yam piston with 19.2mm between the bosses, so 2.2mm clearance. With a wider rod it should not make it out of the small end.

I'm not overly happy with the 2.5mm rollers (making for a 14x19 bearing) that only has 11 rollers, but they seem to go ok in std bikes. Most of the 18x14 brgs seem to run 12 rollers.

Maybe you should have offered a Chocolate fish?
As for the width stuff not sure ....
but I do share your concerns regarding 19x14mm small ends and how often do we agree on anything.(other than to disagree)
Samarin i think had same other widths (i think). I personally would rather go 18x14mm and then some beautiful billet silver plated ones are available in these sizes and are freely available.

I think your case is a rare example when Honda parts should not be used in your Honda powered Honda framed er...Non Honda.

Added a frame pic for TZ
I think this frame is an 1994 Aprilia 125 as well BTW.
Its from the Aussie GP at Eastern Creek.

[2T Institute]

Maybe you should have offered a Chocolate fish?
As for the width stuff not sure ....
but I do share your concerns regarding 19x14mm small ends and how often do we agree on anything.(other than to disagree)
Samarin i think had same other widths (i think). I personally would rather go 18x14mm and then some beautiful billet silver plated ones are available in these sizes and are freely available.

I think your case is a rare example when Honda parts should not be used in your Honda powered Honda framed er...Non Honda.

Added a frame pic for TZ
I think this frame is an 1994 Aprilia 125 as well BTW.
Its from the Aussie GP at Eastern Creek.

That's a TZ125 4JT frame not an Aprilia. Have used the 14 X19 small end in a kart motor that lived at 14,000 only one to fail was when we were forced to run a bearing for the extra meeting when the supplier was out of stock. With the width of the bearing according to my crank bloke( a clever Kiwi as well :bleh:) there was a certain year TZ that switched to a wider bearing, with the rollers poking out the sides of the rod, that solved lots of small end drama's on the previous model.

[husaberg]

That's a TZ125 4JT frame not an Aprilia. Have used the 14 X19 small end in a kart motor that lived at 14,000 only one to fail was when we were forced to run a bearing for the extra meeting when the supplier was out of stock. With the width of the bearing according to my crank bloke( a clever Kiwi as well :bleh:) there was a certain year TZ that switched to a wider bearing, with the rollers poking out the sides of the rod, that solved lots of small end drama's on the previous model.

:stupid:Well i bow my head in shame. nah not really i just thought it looked to right to be a Y.A.M.A.hoo.:o
Does explain why it is striped done though as it probably blew up trying to keep up with a Honda or Aprilia

I thought this was interesting.
The R0.5 Minimono (half an R1 - geddit??) came together after a deal was brokered with Yamaha Europe to supply a YZ426 engine - the Japanese giant’s Euro-HQ in Amsterdam is full of people interested in Supermono racing, and the chance to see how the firm’s new generation of ground-breaking off-road four-strokes would perform on tarmac, has been an unanswered question many of them were eager to resolve. Dave Pearce initially planned to match this motor up with a TZ125 chassis sourced from his fomer race mechanic Katsuaki Umemoto, who today runs Tigcraft Japan - but opted instead to design his own Tigcraft tubular steel frame for the bike while retaining the Yamaha suspension, because of the vibration and extra stresses which a heavier, torquier fourstroke engine would impose on the 125 GP bike’s aluminium Deltabox chassis, typified by the fact that it broke the TZ125 cushdrive the first time they tried to bumpstart it!

http://www.designdatamanager.com/images/Cathca2.jpghttp://www.designdatamanager.com/images/Cathca1.jpghttp://www.designdatamanager.com/images/Cathca4.jpghttp://t3.gstatic.com/images?q=tbn:ANd9GcSycLdph4iio4iTfx8uh6GtKVXQto4yG in1H9r6G7L1aFpBFMKrqg
Chassis geometry is the same as the TZ125 which inspired the bike, with a 22-degree head angle and just 82mm of trail from the 35mm Kayaba upside down forks, which retain the same springs as on the GP bike they’re sourced from, with only slightly stiffer damping settings. The GP racer’s aluminium swingarm is also retained, pivoting in the vertically-split engine cases and working a Dutch-made TechnoFlex shock via the stock TZ125 rising-rate link. "The shock is exactly as supplied for a 125 GP road racer, but with 25% more rebound damping, which we’ve found seems to suit big-pistoned singles better," says Dave Pearce. Fitted with RS125 Honda polycarb bodywork, but a special aluminium Tigcraft fuel tank reflecting the greater bulk of the four-stroke engine, the R0.5 Minimono weighs in at just 88 kg. with oil and water, but no fuel - a figure achieved without the use of any titanium, says Pearce, apart from the bolts securing the single 300mm front Braking petal disc, and its 185mm rear counterpart. "It’s important to stress that this is a very low-budget bike," says Dave. "We effectively have no carbon-fibre or titanium in it at all, and it’s been designed to readily accept the running gear from any Honda RS125R or Yamaha TZ125. It’s hard to over-emphasise how completely different the Minimono is to ride compared to the Gallina or another of the big 700cc-plus singles - though ironically it does share quite a lot in common in terms of technique and riding style with a Ducati Supermono. That’s because the key to redressing La Ducatina’s horsepower and weight disadvantages compared to the maxi-singles has always been to exploit its sweet handling and extreme 54/46% frontal weight bias (thanks to the horizontal cylinder’s heavy desmo head) to maintain corner speed and keep up momentum. The R0.5 has the same weight distribution, and asks you to ride it the same way, making the guff about the danger posed by conflicting lines through corners from little and large,
http://www.designdatamanager.com/scorpion-racing/minimono/mainbody.html

[RAW]

Hello all, great forum, great to see a bunch of enthusiest sharing ideas, knowledge & encourigement

My question, can anyone assist with the direction to the page where Frits Overmars mentioned, fuel pump type / site link, pressure ect upon the Aprillia

Cheers all, keep up the great sharing of a common interest, Without competers we all LOOSE

[kel]

That's a TZ125 4JT frame not an Aprilia.
Would make a great bucket. There's a TZ125 chassis on Yahoo Japan for approximately $280NZ
263202
Shame they don't offer overseas shipping

[husaberg]

Would make a great bucket. There's a TZ125 chassis on Yahoo Japan for approximately $280NZ
263202
Shame they don't offer overseas shipping

We do have a Japan based contributor remember, where is he has been a bit quiet lately. Maybe he is bored and ........

I work at Asaka, ( actually it s asakadai , next station up ) and I can vouch for that article ,
Stephen
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=263191&stc=1&thumb=1&d=1336180360
We import thousand's of second hand cars per year into new Zealand imagine how many frames someone (say Stephen) could stuff in a say a Second hand Hiace van.
I also think Bert may have a contact in Japan as well.

Tigercraft from Grumph as well

[Frits Overmars]

Improving the handling by moving the engine forward to put more weight on the front wheel.
Its hard to see what can be done. There is already quite a distance between the front sprocket and swing arm pivot, and it doesnt look wise to increase it. I agree. But how much is your wheelbase? Bringing the front wheel back towards the engine might be an option. Riding against a brick wall is the quickest solution, but it is rather difficult to bend both fork tubes exactly the same amount. Dropping the head stock is a better idea. Maybe you can shorten the lower fork legs so you can get the tire closer to the lower yoke. And / or you can revert that lower yoke which will give you more room to move the fork tubes up in the yokes before the lower fork legs hit that yoke.
On the dyno under power this bike has a definit squat, is that good or bad? does it unload the front wheel in a corner? this bike does suffer from front end chatter when pushed hard.Squat does not unload the front wheel; it drops the center of gravity so your rate of acceleration is less limited by wheelie-tendencies (which may not be all that important for a bucketracer). Chatter can come from anywhere: tires, damping, frame flexing; just ask poor Valentino Rossi.
Maybe shortening the frame rails to bring the front wheel back to the engine is a possibilityIf you do that, you may want to steepen the fork angle as well. You can go well below 20°, provided you watch the trail; it should be about 85 to 95 mm for your kind of bike and tires, and you can control it with yoke offset. Optimum would be yoke offset zero, as this would bring the masses of forks and wheel closer to the steering axis. That reduces steering inertia; it leaves more wheel feedback to reach the handlebars which will give the rider a better impression of the available grip and a lot more confidence in the bike.
Yes, improving the handling is something we are very interested in.That is very good, but by now you may have gathered it is a rather complicated matter; not something I can explain on a saturday morning.

[F5 Dave]

. Have used the 14 X19 small end in a kart motor that lived at 14,000 only one to fail was when we were forced to run a bearing for the extra meeting when the supplier was out of stock. With the width of the bearing according to my crank bloke( a clever Kiwi as well :bleh:) there was a certain year TZ that switched to a wider bearing, with the rollers poking out the sides of the rod, that solved lots of small end drama's on the previous model.
Thanks for the input.

Ideas anyone on clearance. is 2.2 total waay too much?

[TZ350]

Yes, improving the handling is something we are very interested in.


I agree. But how much is your wheelbase? Bringing the front wheel back towards the engine might be an option, but by now you may have gathered it is a rather complicated matter; not something I can explain on a saturday morning.
From memory, the wheel base is 140mm longer than the Honda RS and I can realistically cut about 100mm out of the frame rails and maybe get the rest by steepening the forks.

I am grateful for your input, I will make a start with what you have told me already and post my progress as I go, any tips or suggestions along the way will be welcome.

[TZ350]

... yoke offset. Optimum would be yoke offset zereo, as this would bring the masses of forks and wheel closer to the steering axis. That reduces steering inertia; it leaves more wheel feedback to reach the handlebars which will give the rider a better impression of the available grip and a lot more confidence in the bike.

Thanks for the insight ...


Maybe you can shorten the lower fork legs so you can get the tire closer to the lower yoke. And / or you can revert that lower yoke which will give you more room to move the fork tubes up in the yokes before the lower fork legs hit

Inverting the bottom yoke for clearance, good idea, I will look into it ...


... you may want to steepen the fork angle as well. You can go well below 20°, provided you watch the trail; it should be about 85 to 95 mm for your kind of bike and tires, and you can control it with yoke offset.

My bike is 22.5 deg and the RS is 21 as best as I can tell. How much below 20 is sensible?

[speedpro]

I have a similar 3LN FZR chassis with emulators in the front forks and the suspension setup exactly as Robert Taylor said but with one turn extra on the emulator adjustors. I've slid the triple clamps down the forks about 20mm and with no springs, fully compressed the forks "just" touch the bottom of the triple clamp. I was looking at the chassis tonight trying to see where it could be shortened and it isn't obvious yet. One thing I am considering is moving the motor forward, maybe 100mm or so, but as mentioned the sprocket ends up a long way from the swingarm pivot. I'm thinking maybe a cambelt tensioner mounted on the 10mm adaptor plate with a small sprocket on the outside, set back close to the pivot. My thoughts were to fully compress the rear suspension and mount the motor low enough so that the chain just runs on the roller. The cam belt tensioner has an eccentric mounting system to allow adjustment which might be useful as well. I was actually looking at doing this engine relocation with a view to achieving something else. I also just thought that I could turn the unused top part of the alloy lower fork legs off allowing the triple clamps to be slid down a bit more. It's nice and stable so can be made a bit steeper yet.

[F5 Dave]

Thanks for the insight ...



Inverting the bottom yoke for clearance, good idea, I will look into it ...



My bike is 22.5 deg and the RS is 21 as best as I can tell. How much below 20 is sensible?

When I measured my RS it was 23 fairly cranked up. my gauge is a 3' long tube on a pivot drilled in a reasonable decent size of ply that can be flat on the ground & with lines scribed from a large protractor. The long tube means easier to line up with the fork tube in a few places.

You'll know when you've gone too far, the bike will self steer when leaned over & its bloody 'orrible.

[husaberg]

When I measured my RS it was 23 fairly cranked up. my gauge is a 3' long tube on a pivot drilled in a reasonable decent size of ply that can be flat on the ground & with lines scribed from a large protractor. The long tube means easier to line up with the fork tube in a few places.

You'll know when you've gone too far, the bike will self steer when leaned over & its bloody 'orrible.


I had saved this stuff from a while back this his how the RS125 Honda frames seem to stack up STD.

http://www.fatbaq.com/rs125/1991.jpg
Year: 1991
Make: HONDA
Model: RS125R

Item Specification
Dimensions Overall length 1,830 mm
Overall width 560 mm
Overall height 985 mm (38.8 in)
Wheelbase 1,260 mm
Ground clearance 110 mm (4.3 in)
Dry Weight 68 kg
Half dry weight 71 kg (156 lbs)
Frame Caster angle 25 °
Trail length 95 mm
Tire pressure-Front 1.8kg/cm2
Tire pressure-Rear 2.0kg/cm2
Tire size-Front 2.65 x 3.25-17
Tire size-Rear 2.85 x 4.00-17
Front brake Single disc / 296 mm
Rear brake Single disc / 186 mm
Suspension-Front Telescopic 90 mm
Suspension-Rear Swingarm 110 mm
Frame type Twin tube
Fork oil capacity 210 cc
Fuel system Fuel capacity 12 liter
Mixing ratio 30:1

http://www.fatbaq.com/rs125/1997_alt.jpg
1997 Honda RS125 Specifications
Item Specification
Dimensions Overall length 1,800 mm (70.9 in)
Overall width 570 mm (22.4 in)
Overall height 985 mm (38.8 in)
Wheelbase 1,215 mm (47.8 in)
Ground clearance 110 mm (4.3 in)
Seat height 700 mm (27.6 in)
Half dry weight 71 kg (156 lbs)
Frame Type Aluminum twin tube
Front suspension Telescopic, inverted type
Rear suspension Swingarm, Pro-link
Front brake Single disc / 4 piston caliper
Rear brake Single disc / 1 piston caliper
Fuel capacity 13.0 liter (3.4 US gal)
Caster angle 23 ° 30'
Trail length 84mm (3.3 in)
http://www.fatbaq.com/mainpage.phtml?topic=rs125_timeline
The next candidates for the wind tunnel test were the 1990 and 1996 Honda RS125 GP bikes. To look at the bikes, you'd expect the more current model to have the more slippery shape. The older RS has a blunter nose and a sharply cut-off tailsection, which don't "look" aerodynamic. But the wind tunnel proved otherwise
http://www.sportrider.com/tech/146_0106_aero/index.html

[richban]

I had saved this stuff from a while back this his how the RS125 Honda frames seem to stack up STD.

http://www.fatbaq.com/rs125/1991.jpg
Year: 1991
Make: HONDA
Model: RS125R

Item Specification
Dimensions Overall length 1,830 mm
Overall width 560 mm
Overall height 985 mm (38.8 in)
Wheelbase 1,260 mm
Ground clearance 110 mm (4.3 in)
Dry Weight 68 kg
Half dry weight 71 kg (156 lbs)
Frame Caster angle 25 °
Trail length 95 mm
Tire pressure-Front 1.8kg/cm2
Tire pressure-Rear 2.0kg/cm2
Tire size-Front 2.65 x 3.25-17
Tire size-Rear 2.85 x 4.00-17
Front brake Single disc / 296 mm
Rear brake Single disc / 186 mm
Suspension-Front Telescopic 90 mm
Suspension-Rear Swingarm 110 mm
Frame type Twin tube
Fork oil capacity 210 cc
Fuel system Fuel capacity 12 liter
Mixing ratio 30:1

http://www.fatbaq.com/rs125/1997_alt.jpg
1997 Honda RS125 Specifications
Item Specification
Dimensions Overall length 1,800 mm (70.9 in)
Overall width 570 mm (22.4 in)
Overall height 985 mm (38.8 in)
Wheelbase 1,215 mm (47.8 in)
Ground clearance 110 mm (4.3 in)
Seat height 700 mm (27.6 in)
Half dry weight 71 kg (156 lbs)
Frame Type Aluminum twin tube
Front suspension Telescopic, inverted type
Rear suspension Swingarm, Pro-link
Front brake Single disc / 4 piston caliper
Rear brake Single disc / 1 piston caliper
Fuel capacity 13.0 liter (3.4 US gal)
Caster angle 23 ° 30'
Trail length 84mm (3.3 in)
http://www.fatbaq.com/mainpage.phtml?topic=rs125_timeline
The next candidates for the wind tunnel test were the 1990 and 1996 Honda RS125 GP bikes. To look at the bikes, you'd expect the more current model to have the more slippery shape. The older RS has a blunter nose and a sharply cut-off tailsection, which don't "look" aerodynamic. But the wind tunnel proved otherwise
http://www.sportrider.com/tech/146_0106_aero/index.html



FXR 150
Caster: 24 degrees
Trail: 85 mm

Mine is jacked 10mm in the rear must measure it. Handles fab. Just a heap of flex. Hey but what you don't know won't hurt you. Must ride some more bikes.

[Ocean1]

One thing I am considering is moving the motor forward, maybe 100mm or so, but as mentioned the sprocket ends up a long way from the swingarm pivot. I'm thinking maybe a cambelt tensioner mounted on the 10mm adaptor plate with a small sprocket on the outside, set back close to the pivot. My thoughts were to fully compress the rear suspension and mount the motor low enough so that the chain just runs on the roller.

Looong time ago my old man built a frame from scratch, the countershaft drive went to a sprocket on the swingarm pivot, another from there to the rear axle. It's almost certainly been done elsewhere too.

Doubt you've got room for twin sprockets on the pivot, but if you can manage it you get to put your motor wherever you like. You also get to reduce unsprung weight by making the rear sprocket much smaller.

[Brian d marge]

We do have a Japan based contributor remember, where is he has been a bit quiet lately. Maybe he is bored and ........

http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=263191&stc=1&thumb=1&d=1336180360
We import thousand's of second hand cars per year into new Zealand imagine how many frames someone (say Stephen) could stuff in a say a Second hand Hiace van.
I also think Bert may have a contact in Japan as well.

Tigercraft from Grumph as well
One of the biggest problems is the shipping back to NZ , I have just wrapped a frame up , and it will get there but its not very efficient .

if someone can show me a way I dont mind ( time is tight but ,,, )

Stephen

[casal-fan]

Squat does not unload the front wheel; it drops the center of gravity so your rate of acceleration is less limited by wheelie-tendencies

Isn`t a wheelie the outermost sublime manifestation of unloading the front wheel?
The back squating, appears to be a manifestation of center of gravity shifting backwards, thus removing weight from the front wheel...???
Sorry, I´m not getting it.

[TZ350]

The back squating, appears to be a manifestation of center of gravity shifting backwards, thus removing weight from the front wheel...???
Sorry, I´m not getting it.

Sorry, I hadn't realy thought about it and should have explained that the squating compresses both the front and back suspension. I think the bike basically hinges in the middle at the swing arm pivot and the whole bike squats down. I will try and get a video clip of it next time its on the dyno and then we can see for sure whats happining.

[Buckets4Me]

for those fans of TT3D close to the edge

<iframe src="http://www.youtube.com/embed/zgSo6nxuH7U" allowfullscreen="" frameborder="0" height="315" width="420"></iframe>


<iframe width="420" height="315" src="http://www.youtube.com/embed/KGQQFh4aHpM" frameborder="0" allowfullscreen></iframe>

[bucketracer]

... the squating compresses both the front and back suspension. I will try and get a video clip of it next time its on the dyno ...

Its possible that the front suspension is compressed as a reaction to the bike driving the dyno drum around.

[Yow Ling]

Instead of shortening the frame to redistribute the weight , why not move the fuel forward you could put it up by the steering stem just inside the frame rails that would move 2 or 3 kg forward, maybe but the battery in there as well, adjust the bars so you have more rider forward, motor can stay where it was happy

[Buckets4Me]

Its possible that the front suspension is compressed as a reaction to the bike driving the dyno drum around.

my rs would rise up as the back wheel moved closer to the frount wheel pushing the seat and tank up

[casal-fan]

Sorry, I hadn't realy thought about it and should have explained that the squating compresses both the front and back suspension. I think the bike basically hinges in the middle at the swing arm pivot and the whole bike squats down. I will try and get a video clip of it next time its on the dyno and then we can see for sure whats happining.


Its possible that the front suspension is compressed as a reaction to the bike driving the dyno drum around.

Maybe the piece that is missing is simple.
Squat alone, will unload the front wheel. But there are countermesures in the chassi design to control squat, and reestablish chassi geometri.
Simplyfied, these countermesures would be swingarm angle, lenght, and chain sprockets position in relation to each other.

Saying that squat alone will not unload the front wheel, might cause misunderstandings.

http://www.youtube.com/watch?v=XflVAlCbIKI
In this video, the machine is fastened very close to the swingarm pivot point.
Watch how the front compresses when wheel is under acceleration. In a normal dinamic situation, rear squat would occour.
Rear squat, combined with chassi contermesures, and chassi tune would have something to say in a out of corner acceleration f.exe.

[TZ350]

http://www.youtube.com/watch?v=XflVAlCbIKI
In this video, the machine is fastened very close to the swingarm pivot point.
Watch how the front compresses when wheel is under acceleration. In a normal dinamic situation, rear squat would occour.

Good video, yes my bike compresses the forks like that, will try and get a video next time.

[wobbly]

The back squating under power is a function of the top chain pull force vector pulling the rear wheel upwards, not a C of G shift issue..
But get the front sprocket position in relation to the wingarm pivot correct,and you can reverse this force and produce anti squat.
This is why many production type class racers convert to way smaller front and rear sprockets, it lowers the top chain pull.
Look up the many references to anti squat geometry, its easy to understand when you see the forces at work.
I first saw this at Fast By Ferrachi in USA where he had a 916 on the Dynojet.
By simply moving the swingarm pivot up or down, they could make the rear drop, or rise under full throttle power runs - the bike effectively didnt move at all to change the C of G - it simply raised or dropped
the rear due to chain pull.
Rear squat that cant be dialled out by geometry change, can be ameliorated by adding some rear preload and some more compression damping.
We did this on Discombes TZ350 , then he went from not just winning Junior Pre 82 , and breaking lap records,to getting to the front of Senior as well.
An extra 3 turns of rear spring preload and 2 com clicks stopped the rear squat from unloading the front, that even with emulators would go mad as he came off trailing throttle into the power on sweepers.
With the new setting he can power drift both ends, mid turn, with the throttle pinned.

[husaberg]

The back squating under power is a function of the top chain pull force vector pulling the rear wheel upwards, not a C of G shift issue..
But get the front sprocket position in relation to the wingarm pivot correct,and you can reverse this force and produce anti squat.
This is why many production type class racers convert to way smaller front and rear sprockets, it lowers the top chain pull.
Look up the many references to anti squat geometry, its easy to understand when you see the forces at work.
I first saw this at Fast By Ferrachi in USA where he had a 916 on the Dynojet.
By simply moving the swingarm pivot up or down, they could make the rear drop, or rise under full throttle power runs - the bike effectively didnt move at all to change the C of G - it simply raised or dropped
the rear due to chain pull.
http://image.sportrider.com/f/18135606+w750+st0/146_0904_14_z+aprilia_rsv4_factory+CADadj_swingarm _pivot.jpghttp://image.sportrider.com/f/8999478/146_0404_2004_yamaha_R1_14_engine_z.jpghttp://t2.gstatic.com/images?q=tbn:ANd9GcRF6JeALnZz5QSbJpBLP7pjTz2q3BjXO lV_hTE-E_7uxTGNNFPhXilOPyAnhttp://www.reach.net/~seven/rc30_c.JPG
Performance bikes (I think)did a write up on dialing out squat in relation to the Kawa ZX900R.
The initial 900 suffered a lot from squat it unlike the ZXR750 was not equipped with an adjustable swing arm pivot.
If we were to take a look at pretty much all the Gp500's and most all the superbikes from the 90's on, the GP500's also had movable engine mounts for the most part had this feature.(they incidentally alleviated the situation with a new shock with more comp damping and and link plus a different counter-shaft sprocket)

A notable exception was the Honda RC45 and look how long this took to get right and in the end it needed a 5 foot psycho.
I am not say the bucket needs it as moving the engine is a much better idea.

[SwePatrick]

This is cool..

It confirmes my theories about how 'wheeliehappy' different chassies are.
I have on my MB5 raceproject made adjustable brackets för swingarm.
Very very simple and only three different holes to choose from.
It´s a test this summer.. i´m hoping i´ll manage without wheeliebars just to get the look of the bike correct :)

Rgds.

[F5 Dave]

2nd bump. I don't want to run thrust washers if I can avoid it.

ok, a question for the panel;
. . .
So I'm left with the suitability question over 17mm wide MB SE bearing in a Yam piston with 19.2mm between the bosses, so 2.2mm clearance. With a wider rod it should not make it out of the small end.

I'm not overly happy with the 2.5mm rollers (making for a 14x19 bearing) that only has 11 rollers, but they seem to go ok in std bikes. Most of the 18x14 brgs seem to run 12 rollers.

[TZ350]

Year: 1991 HONDA RS125R
Item Specification
Wheelbase 1,260 mm
Dry Weight 68 kg
Half dry weight 71 kg (156 lbs)
Frame Caster angle 25 °
Trail length 95 mm
Suspension-Front Telescopic 90 mm
Suspension-Rear Swingarm 110 mm
Fork oil capacity 210 cc
Fuel system Fuel capacity 12 liter

1997 Honda RS125 Specifications
Item Specification
Wheelbase 1,215 mm (47.8 in)
Half dry weight 71 kg (156 lbs)
Front suspension Telescopic, inverted type
Rear suspension Swingarm, Pro-link
Fuel capacity 13.0 liter (3.4 US gal)
Caster angle 23 ° 30'
Trail length 84mm (3.3 in)




NSR MC16

Wheelbase 1360mm
Seat Height: 750mm
Weight: 125Kg
Castor: 26° chopper like
Trail: 103mm as above



My NSR MC21 Frame

Castor 23° 15'
Trail: 87mm
Wheelbase 1340mm
Seat Height: 770mm

Some basic data on my FZR250 3LN Frame:
Caster Angle 24.5 deg which is 0.5* less than a 91 RS125 @25*
Trail 87mm which is 8mm less than a 91 RS125 @ 95mm
Wheelbase 1,375mm which is 115mm longer than a 91 RS125 @ 1,260 mm
Front fork travel 130mm which is 40mm longer than a 91 RS125 @ 90 mm
Fork Oil 10w
Front Spring Rate 7.8N/mm
Rear wheel travel 117mm which is 7mm longer than a 91 RS125 @ 110 mm
Shock absorber travel 50mm
Spring free length 173mm
Fuel Tank capacity, 14Ltrs
Original dry weight 146kg, oil and full tank 166kg

263326

Some other quickly measured comparisons.

Rear axle to swing arm, 3LN 510mm 91 RS125 455mm
Front axle to swing arm, 3LN 860mm 91 RS125 815mm
Seat Height, 3LN 730mm 91 RS125 675mm
Foot Peg to Seat 3LN 415mm 91 RS125 340mm
Front Axle to crank 3LN 630mm 91 RS125 480mm

And Stearing Head to the front of the Seat, 3LN 630mm 91 RS125 630mm

So I wont be shortening the chassis rails to bring the front wheel back but I might shorten the forks to lower the front end and steepen the caster angle. Also reducing the height of the tank and implementing some of Yow Lings weight forward suggestions and Richbans rear end lightening ideas could be the go.

[husaberg]

Some basic data on my FZR250 3LN Frame:
Caster Angle 24.5 deg 22 deg
Trail 87mm
Wheelbase 1375mm 1275
Front fork travel 130mm
Fork Oil 10w
Front Spring Rate 7.8N/mm
Rear 117mm
Shock absorber travel 50mm
Spring free length 173mm
Fuel Tank capacity, 14Ltrs
Original dry weight 146kg, oil and full tank 166kgn 75kg http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=263178&stc=1&thumb=1&d=1326352786

A bit easier to do with the computer than for real:soon:

NSR MC16
Length: 2035mm
Width: 705mm
Height: 1105mm
Wheelbase 1360mm
Seat Height: 750mm
Ground Clearance: 135mm
Weight: 125Kg
Fuel Tank: 16 litre (primary)1.2 litre (reserve)
Castor: 26° chopper like
Trail: 103mm as above

[richban]

My NSR MC21 Frame

Castor 23° 15'
Trail: 87mm
Length: 1975mm
Width: 655mm
Height: 1060mm
Wheelbase 1340mm
Ground Clearance: 135mm
Seat Height: 770mm

[husaberg]

Some basic data on my FZR250 3LN Frame:
Caster Angle 24.5 deg which is 0.5* less than a 91 RS125 @25*
Trail 87mm which is 8mm less than a 91 RS125 @ 95mm
Wheelbase 1,375mm which is 115mm longer than a 91 RS125 @ 1,260 mm
Front fork travel 130mm which is 40mm longer than a 91 RS125 @ 90 mm
Fork Oil 10w
Front Spring Rate 7.8N/mm
Rear wheel travel 117mm which is 7mm longer than a 91 RS125 @ 110 mm
Shock absorber travel 50mm
Spring free length 173mm
Fuel Tank capacity, 14Ltrs
Original dry weight 146kg, oil and full tank 166kg

263326

Some other quickly measured comparisons.

Rear axle to swing arm, 3LN 510mm 91 RS125 455mm
Front axle to swing arm, 3LN 860mm 91 RS125 815mm
Seat Height, 3LN 730mm 91 RS125 675mm
Foot Peg to Seat 3LN 415mm 91 RS125 340mm
Front Axle to crank 3LN 630mm 91 RS125 480mm

And Stearing Head to the front of the Seat, 3LN 630mm 91 RS125 630mm

So I wont be shortening the chassis rails to bring the front wheel back but I might shorten the forks to lower the front end and steepen the caster angle. Also reducing the height of the tank and implementing some of Yow Lings weight forward suggestions and Richbans rear end lightening ideas could be the go.

I would be interested to see the measurements against the NX4 in the ESE stable.
I found this on the Speedpro's thread (i hope he doesn't mind) i also seen this Lovely RS50 framed H100
2001 2003 RS50 Aprilia
24 rake
Trail 102mm
Wheelbase 1280mm
120mm front suspension travel
110mm Rear suspension travel
http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=238719&d=1305195696


Coments re Speedpro FZR framed Bucket.

I've made changes to the riding position. Avalon commented it was like riding a couch with the seat and handlebar positioning. Because of that I've put the original FZR seat back on the bike rather than just sitting on the fibreglass tailpiece and placed the handlebars under the top triple clamp in the original position. Basically it's back to a stock FZR250 riding position. After riding the scooter all week it has a definite head down arse up feel to it. It was OK at the track today and I'm gonna give it a go tomorrow but my thoughts are that the handlebars are going back on top of the triple clamp. For some strange reason I was uncomfortable in the right onto the back straight, running clockwise, and tended to run wide. It also feels like I'd have less chance of saving it if something happened. My right wrist was letting me know about it as well as it's still unhappy after a big crash 30 odd years ago. It "looks" right so I'm thinking it's just me. My son has also commented that I sit upright more than others. could be that I know something others haven't figured out yet though that'd be a first.

[SS90]

Lambretta with MAXIMUM POWER 55 HP on wheel

<iframe src="http://www.youtube.com/embed/OKNy3hGC1YY" allowfullscreen="" frameborder="0" height="315" width="420"></iframe>


I have been looking at some of the Scooter dyno runs on YouTube, here is a Lambretta that makes 55hp, I have no idea of its capacity, though its probably more than 125cc.

Most of the vespas I have seen are 18-20ps for 133cc 22-27ps for 175cc and 30-32ps for 210cc.

Keep looking, 125cc (123.67cc to be exact) Vespas have been putting out more than 28PS for at least 5 years.

There are several kits available that you can simply bolt on and achieve between 24 and 28 PS depending on the exhaust you use, and plenty of people are making bespoke cylinders pushing that limit higher in workshops all over Europe

Sometimes Youtube does not have the answers.

[husaberg]

Keep looking, 125cc (123.67cc to be exact) Vespas have been putting out more than 28PS for at least 5 years.

There are several kits available that you can simply bolt on and achieve between 24 and 28 PS depending on the exhaust you use, and plenty of people are making bespoke cylinders pushing that limit higher in workshops all over Europe

Sometimes Youtube does not have the answers.
10 carotactors I guess they had larger carbs than 24mm then.

Anyway,

As a side note, while I appreciate the fact that the peak horsepower number will vary from Dyno to Dyno, and pay little attention to that, in almost 10 years of operating various Dyno's around the place, I have personally never seen more that 17 P.S and 14 N.M (at the rear wheel) on an air cooled disc valve two stroke, running a 24mm carb.

I have probably done over 200 runs on that type of set up. (on various engines)

Number are just numbers though!

Lookig forward to it Teezeetreefiddy!:2thumbsup

[SS90]

Hm, oh a typo? Well, that's just proves me wrong doesn't it!
I posted a run about 3 years ago from a run on. 133 cylinder with I think 21 or 22 PS (and 24mm carb, (made by a clever chap in late 2002 if memory serves me correctly) which I indicated that that was the highest power 24mm carbed disc valve engine I had seen.

Limitations of available gear ratios limit several factors in engine design/tuning. It would be interesting for someone in Kiwiland to explore the idea of getting an old 4 speed AX100 to crank out some numbers. Must be plenty of those around considering the fact that most of us have up because of the 4 speed gear box!

I also wonder if the Suzuki GP100 has a lower primary drive ratio that the GP125? And, if so, are they interchangeable? This could sort out some of those big gaps between upchanges (Oh and alter you power output on the dyno too)

[Frits Overmars]

Hm, oh a typo? ....I also wonder if the Suzuki GP100 has a lower primary drive ratio that the GP125? And, if so, are they interchangeable? This could sort out some of those big gaps between upchanges.I do hope that is a typo. You can't be serious, altering gear box steps by changing the primary ratio :facepalm:.

[SS90]

I do hope that is a typo. You can't be serious, altering gear box steps by changing the primary ratio :facepalm:.

Not so much a typo, but rather an over simplification.
Shorten the primary drive ratio to alter the gearbox speed, in the situation this engine is in (5 speed commuter Style ratio) this would be an obvious advantage.
Assuming that a GP100 1) has a lower ratio and 2) is compatible.

[bucketracer]

Keep looking, 125cc (123.67cc to be exact) Vespas have been putting out more than 28PS for at least 5 years.

Boys being Boys if anyone actually had a 28ps Vespa you can bet it would be posted on YouTube for his mates to admire.

It would be interesting to see a vid if anyone can find one.

[SS90]

Boys being Boys if anyone actually had a 28ps Vespa you can bet it would be posted on YouTube for his mates to admire.

It would be interesting to see a vid if anyone can find one.

Has it ever occurred to you that YouTube doesn't have the ability to measure engine power output?

[Haufen]

Boys being Boys if anyone actually had a 28ps Vespa you can bet it would be posted on YouTube for his mates to admire.

It would be interesting to see a vid if anyone can find one.

http://www.youtube.com/user/gp1tuningparts

These engines seem to be slightly larger in engine displacement than 125cc, but not by much. 32 hp out of 125cc seems feasible.

[twotempi]

There seems to be an old myth that if you change the primary gear ratio it somehow closes up the gearbox ratios.

As Fritz exclaimed this is definitely a myth.

What happens is that you spin the clutch and gearbox shafts at a different speed , which you then have to allow for by altering the final drive ratio.

However there may be benefits by spinning the clutch faster and thereby reducing the torque loading on the clutch if this component is marginal. BUT you may get bigger internal power loses in the gearbox by churning up the oil more.

[SS90]

:shifty:
There seems to be an old myth that if you change the primary gear ratio it somehow closes up the gearbox ratios.

As Fritz exclaimed this is definitely a myth.

I never claimed that.I said that changing the primary ratio might "sort out" the gaps between up changes.

There doesn't seem like many (any) other options for gear ratios in a GP 125.
Unless someone can point us to a "WikiHow" page on making your own gearbox?

[Yow Ling]

:shifty:

I never claimed that.I said that changing the primary ratio might "sort out" the gaps between up changes.

There doesn't seem like many (any) other options for gear ratios in a GP 125.
Unless someone can point us to a "WikiHow" page on making your own gearbox?

Lucky for us You tube has the how to on this one
about 3 minutes into this video Gabriel Gnani is forging a blank for a new gear

Easy as bro !!

http://www.youtube.com/watch?v=I-2rJtnkYq4&feature=relmfu

[SS90]

Lucky for us You tube has the how to on this one
about 3 minutes into this video Gabriel Gnani is forging a blank for a new gear

Easy as bro !!

http://www.youtube.com/watch?v=I-2rJtnkYq4&feature=relmfu

I just missed one bit, was that 500 degrees or 550 degrees?:msn-wink:

[bucketracer]

I also wonder if the Suzuki GP100 has a lower primary drive ratio that the GP125? And, if so, are they interchangeable? This could sort out some of those big gaps between upchanges (Oh and alter you power output on the dyno too)

I would be interested in seeing the maths that support your assertion that a change in the primary drive ratio alters the power output on the dyno.

263363

A graph you posted of a multi gear run.

Three different overall gear ratios and pretty much the same power output from each.

Changing the primary gear ratio affects the overall gear ratio just like changing gears does. But as we can see from the graph there is no real change in rear wheel hp.



http://www.youtube.com/user/gp1tuningparts
These engines seem to be slightly larger in engine displacement than 125cc, but not by much. 32 hp out of 125cc seems feasible.


<iframe src="http://www.youtube.com/embed/qaryTiIlrzo" allowfullscreen="" frameborder="0" height="315" width="560"></iframe>

154ccm FALC 60x54, Keihin Airstriker 38, Vespatronic, Exhaust: Falc 2011
Extreme 36,3HP an over 27 Nm !!

Yes good find, I knew there had to be some good video clips around. But 154cc is 23% bigger than TeeZeez 125 and the 38mm Airstriker is a bit bigger than the 24 TeeZee is allowed to run.

Which makes TeeZee's 31ps effort from a 1970's cylinder look not too shabby by todays tuning standards in Europe.

It would still be interesting to see something closer to TeeZee's rotary valve 125cc air cooled with a 24mm carb if possible.

[wobbly]

Interested as to why these guys even think that getting an EXTREME 36 Hp from a 150cc special cylinder with a 38mm carb
is worthy of raving about and videoing on U tube.
Take a MX based TM125 cylinder that makes more than that as a 125 and drop in a 60mm piston,port and pipe it with good attention to detail
and it makes over 50 RWHp on a Dynojet twin roller with load control, on UNLEADED pump gas.
Now get excited, but no im not putting it on here nor U Tube.

[Haufen]

Interested as to why these guys even think that getting an EXTREME 36 Hp from a 150cc special cylinder with a 38mm carb
is worthy of raving about and videoing on U tube.
Take a MX based TM125 cylinder that makes more than that as a 125 and drop in a 60mm piston,port and pipe it with good attention to detail
and it makes over 50 RWHp on a Dynojet twin roller with load control, on UNLEADED pump gas.
Now get excited, but no im not putting it on here nor U Tube.

That's true of course. But as these cylinders are limited by the standard stud pattern and air cooling those results (RWHp+unleaded pump gas) are not that bad.

I am not familiar with the bucket regulations. Can you pick any cylinder you want as long as you stay within the 100/125 cc displacement limit?

[SS90]

Interested as to why these guys even think that getting an EXTREME 36 Hp from a 150cc special cylinder with a 38mm carb
is worthy of raving about and videoing on U tube.
Take a MX based TM125 cylinder that makes more than that as a 125 and drop in a 60mm piston,port and pipe it with good attention to detail
and it makes over 50 RWHp on a Dynojet twin roller with load control, on UNLEADED pump gas.
Now get excited, but no im not putting it on here nor U Tube.

I heard somewhere you have worked with Jim Lomis there Wobbly.... He does quite a bit of work with Tuned Vespas (although he is not, nor does he claim to be, at the forefront of technology)

But that aside, have you ever tried to implement many of the things you have talked about on here through a 4 speed box before? (this is just a question, nothing inflammatory intended)

The GP 125 current woes seem to me to be exasperated by this drive for high RPM (with pipe designs all aiming for 14,000 plus rpm)

I have shown several dyno runs with similar peak power, just thousands of rpm less, and over a far wider "band"

This is neither difficult, nor costly to achieve.

I see that Speedpro's engine is "the business" as far as power goes, but, from what I understand, not doing much winning, even with it's advantage (over Teezee's) of a 6 ratio box.

I would again put forward the idea of reducing certain aspects of the engine(s), particularly the blowdown time (therefore Peak power rpm range) and building a pipe to suit.

Like I say, less is more. Particularly when you have shitty gear ratios to play with.

Speedpro has mentioned recently that he plans to run something like 192 degrees, with his single exhaust port, being limited in his width and therefore blowdown T/A, if he manages to develop a pipe to suit, going through a 6 speed box, this, in my experience should be a real weapon, all happening below 10,500 RPM

Should be worth watching.

[Yow Ling]

. Can you pick any cylinder you want as long as you stay within the 100/125 cc displacement limit?

Yes
100cc any cylinder any carb, 125 aircooled only plus carb restriction

[F5 Dave]

Ohh look page 500. 3rd bump then I give up



2nd bump. I don't want to run thrust washers if I can avoid it.
Originally Posted by F5 Dave http://www.kiwibiker.co.nz/forums/images/buttons/viewpost-right.png (http://www.kiwibiker.co.nz/forums/showthread.php?p=1130316514#post1130316514) ok, a question for the panel;
. . .
So I'm left with the suitability question over 17mm wide MB SE bearing in a Yam piston with 19.2mm between the bosses, so 2.2mm clearance. With a wider rod it should not make it out of the small end.

I'm not overly happy with the 2.5mm rollers (making for a 14x19 bearing) that only has 11 rollers, but they seem to go ok in std bikes. Most of the 18x14 brgs seem to run 12 rollers.

[Yow Ling]

I just missed one bit, was that 500 degrees or 550 degrees?:msn-wink:

Heres a colour chart to help you , looks around 800°C

263366

[SS90]

That's true of course. But as these cylinders are limited by the standard stud pattern and air cooling those results (RWHp+unleaded pump gas) are not that bad.

I am not familiar with the bucket regulations. Can you pick any cylinder you want as long as you stay within the 100/125 cc displacement limit?

Limted by the stud pattern? Not so, there are plenty of conversions getting around using adapter plates, most of which are water cooled.

The "plug and play" concept limits the stud patterns of course, but that's easily overcome (like Lauros solution for boysen ports)

The big limitation for race engine power is available gear ratios, and, in the event that this cannot be altered (zirri short fourths only have certain advantages) you have to make sacrifices in regards to peak power in return for a wider spread at a lower RPM.

This is one reason why Lambretta tuners can make bigger numbers than Vespa tuners... lambretta models have many different gear ratios, most all of which are interchangeable between
Engines, meaning even though they only have 4 ratios, there exists a possibility to build a gearbox with suitable gear ratios for a peakier engine.

[Kickaha]

That's true of course. But as these cylinders are limited by the standard stud pattern and air cooling those results (RWHp+unleaded pump gas) are not that bad.

I am not familiar with the bucket regulations. Can you pick any cylinder you want as long as you stay within the 100/125 cc displacement limit?

Bucket rules here http://apps.facebook.com/inthemafia/track.php?next_controller=war&next_action=view&zy_track=feed&sendkey=5af3964d24f1e25b6637e906d0451798%24%24ihF2 T_S.5YyMY4M7yLRW%21PNC_YhGMEzJUAlr9qjS-dsP8fHuJ428EJMCsG%21-hJsmOFKHBlaM1.ny53fMA%29J4%21nVbuHRS-9byVJmcc%2Az&next_params=%7B%22leader_id%22%3A%22p%7C2050528%22 %7D

It can't be a competiton/race cylinder

[SS90]

Heres a colour chart to help you , looks around 800°C

263366

I might have misheard, but he didn't mention 800 degrees, I am sure he said 550 degrees, but I didn't watch all the way through.

[bucketracer]

Page 500 .....

No need to have a peaky engine. Here are Two Very useful Tools. EngMod2T a 2-Stroke simulation package and a handy (and cheep) Porting Calculator from:- http://www.porting-programs.com/ which is based on Blairs work.

263589Rich's 4-Stroke


Because a few people have asked about the GP engine, to save wading through 500 pages, these links go to the more relevant posts about building a reliable high 20's hp engine.

263593 27hp 1978 Suzuki GP125


And for something a little more radical for the adventurous ..... The basic info for building a 30+hp Suzuki GP125

263587 30hp 1978 Suzuki GP125

There are over 3,500 images on this thread. To find the interesting ones use Thread Tools near the top of this page and View Images, then sort them from the Beginning and 70 to a page. Click on the Image to view it and the little N/A sign to go to the Post about it.

On each decade page, 490, 480, 470, 460 etc there is a collection of links or a collection of the more interesting technical posts from the last ten pages.

A bit of an index .....

Page 490 The Trombone, Ex port resonance and Transfer port stagger.
Page 480 A vid of the Trombone, transfer timing and hot gases entering the transfers because of insufficient blow-down for the rpm.
Page 470 Blow-down STA ... Specific Time Area.
Page 460 No list but the page talks about Boost Bottles.
Page 450 Links to the basic info for building a 30+ hp Bucket.
Page 440 No list, page talks about power and air correction jets.
Page 430 Carb inlet lengths and crankcase volumes.
Page 420 Transfer ports and the importance of the up swept angles, the Leaning Tower of Pisa principle explained.
Page 410 Rolling road dynos, main and power jet ratio.
Page 400 Links to the basic info for building a 30hp Suzuki GP125 Bucket engine.
Page 390 Links to Frits collection of Aprilia stuff.
Page 380 Transfer duct shape and STA's.
Page 370 No list but the page talks about Jan Thiel and racing 50's.
Page 360 Frits chamber calculations formula.
Page 350 PJ switching, Wob and crank shaft balance.
Page 340 Muriatic Acid, main brg float, Husburgs con rod dimensions.
Page 330 No list, page talks about expansion chambers, race gas.
Page 320 High temp silicon, Yama Bond, crankcase sealing, air solenoids Vid clips of Mamola.
Page 310 Copper for cooling, sprockets for cooling, steering head brgs.
Page 300 How to determine STA numbers.
Page 290 B/E dimensions, delivery ratio, Honda Ex Step, stinger nozzel
Page 280 Aprilia RSA port layout explained, pumper carb, links to gluing up the GP cases.
Page 270 Link list on how to make a decent high 20's hp Suzuki GP125 Bucket engine.
Page 260 Over rev cough and what it means, Mallory metal for crank balancing.
Page 250 27hp from a 1978 Suzuki GP125
Page 240 Aprilia RSA cylinder stuff.
Page 230 Porting Calculator and a lot of other useful tech links.
Page 220 RG50 part numbers, 2-stroke carb atomisers explained
Page 210 Page is mostly about the results from the TRRS
Page 200 Simple 18 hp Suzuki GP Bucket engine using a RG250 pipe.

Etc ...

[Haufen]

Yes
100cc any cylinder any carb, 125 aircooled only plus carb restriction

I am wondering, how comes nobody has yet started to do "the ugly things", like welding cooling fins to a 125 gp barrel, or taken a powerful 125cc barrel, sleeving and destroking it to get below 100cc, or cast one's own cylinders (would that be allowed)?


Limted by the stud pattern? Not so, there are plenty of conversions getting around using adapter plates, most of which are water cooled.

The "plug and play" concept limits the stud patterns of course, but that's easily overcome (like Lauros solution for boysen ports)

The big limitation for race engine power is available gear ratios, and, in the event that this cannot be altered (zirri short fourths only have certain advantages) you have to make sacrifices in regards to peak power in return for a wider spread at a lower RPM.

Well, I was talking about the engines in the videos, which are aftermarket Falc cylinders that bolt onto the standard stud pattern.

I think you are not quite up to date concerning the available gear ratios, smallframe gearing has become heaven on earth during the last few years.


Bucket rules here http://apps.facebook.com/inthemafia/track.php?next_controller=war&next_action=view&zy_track=feed&sendkey=5af3964d24f1e25b6637e906d0451798%24%24ihF2 T_S.5YyMY4M7yLRW%21PNC_YhGMEzJUAlr9qjS-dsP8fHuJ428EJMCsG%21-hJsmOFKHBlaM1.ny53fMA%29J4%21nVbuHRS-9byVJmcc%2Az&next_params=%7B%22leader_id%22%3A%22p%7C2050528%22 %7D

It can't be a competiton/race cylinder


thanks, now I got it.

[wobbly]

Yes I worked with Jim at JL for a couple of years before I went to work with Hines at Zipkart as factory manager.
Even now Jim has his minions cut patterns by hand as his labour is cheap, lasers cost a fortune, plus the needed CAD packages/operators to suit.

One thing I have mentioned several times here is that the reliability ( or lack of it ) of the recently powerful buckets has nothing to do with the design philosophy
or even an inherent 2T issue.
Its all to do with knowledge base and implementation.
TeeZees thing would never have died , if I had seen the ignition curve before the problem became very publicly obvious ( and you have to admire him and his team showing the world what not to do for free, even
though it costs those guys plenty in time and parts ).

Building a 4 speed is just as easy as building for a 6 speed.
You just plug in the bmep numbers and by default the lower requirements will produce a wider powerband.
Same with the pipe design ,the angles and relative % lengths needed to give as wide a band as is required to stay in the power , its simply a different approach to tuning for high bmep and thus power peaks, at
the expense of width.

Depends at the end of the day on the funds available.
With plenty of cash I would always go for the fattest torque curve with the rpm up near the cranks mechanical limit of say 14000.
This approach with a ton of rpm and a wide powerband will always be faster than the same engine developing its power down at 10500,with the huge advantage of adding several teeth on the
rear sprocket and the physics of torque multiplication, plus the vastly superior sonic tuning available with that higher rpm.
But to use that approach requires a heap of detailed knowledge,and of course that costs money, as anyone can read Bell and Jennings, then build a bucket with good power at 10500, but that
is no longer an option with 30 Hp easily doable - just the finer points need to be addressed and those guys will be GONE, 20M ahead at the first corner.

PS - if ANYONE can do a 125 Aircooled with 24mm carb and make anything like 30 Hp at 10500, then its here in writing - free blowys for life.

[SS90]

I think you are not quite up to date concerning the available gear ratios, smallframe gearing has become heaven on earth during the last few years.


"heaven on earth" how so?

Last time I checked (this afternoon) small frames are all 4 speed, and other than some short fourth manufacturers, you are limited to either an ET3, PK80 SS50 or Primavera übersetzung... Although the 50s had a "long fourth", and works well with certain set ups.

[SS90]

Building a 4 speed is just as easy as building for a 6 speed.
You just plug in the bmep numbers and by default the lower requirements will produce a wider powerband.
Same with the pipe design ,the angles and relative % lengths needed to give as wide a band as is required to stay in the power , its simply a different approach to tuning for high bmep and thus power peaks, at
the expense of width.

Depends at the end of the day on the funds available.
With plenty of cash I would always go for the fattest torque curve with the rpm up near the cranks mechanical limit of say 14000.
This approach with a ton of rpm and a wide powerband will always be faster than the same engine developing its power down at 10500,with the huge advantage of adding several teeth on the
rear sprocket and the physics of torque multiplication, plus the vastly superior sonic tuning available with that higher rpm.
But to use that approach requires a heap of detailed knowledge,and of course that costs money, as anyone can read Bell and Jennings, then build a bucket with good power at 10500, but that
is no longer an option with 30 Hp easily doable - just the finer points need to be addressed and those guys will be GONE, 20M ahead at the first corner.

At this stage, it remains to be seen, as even when Teezees bike was peddled by a featherweight rider, it wasn't winning anything before expiring. Although, when the same rider was riding a bike with substantially less power it by all accounts it cleaned up.

To me there is a clear case for building a bike that is easier to ride, and handles better (like stick a tamer engine in an RS chassis)

Im still quite dismayed that after all this, FXR 1fucking50s are still the standard.

[bucketracer]

I am wondering, how comes nobody has yet started to do "the ugly things", like welding cooling fins to a 125 gp barrel, or taken a powerful 125cc barrel, sleeving and destroking it to get below 100cc, or cast one's own cylinders (would that be allowed)?

In F4 a 100cc 2-Stroke can be water cooled and have any size carb, a 125 must be air cooled and is restricted to a 24mm carb.

TeeZee has managed to make 31 hp with his old 125cc air cooled engine from the 70's and with some development I expect he will get it reliable too.

Casting your own cylinder is allowed and a pretty impressive thing to do. RGV250 cylinders have been sleeved down to 100. And TeeZee has looked at air cooling one too. RG400 cylinders are/were also popular.

Basically anything you make or can modify from a non-compitition engine is allowed.

[bucketracer]

Im still quite dismayed that after all this, FXR 1fucking50s are still the standard.

WE feel your pain ...


At this stage, it remains to be seen, as even when Teezees bike was peddled by a featherweight rider, it wasn't winning anything before expiring. Although, when the same rider was riding a bike with substantially less power it by all accounts it cleaned up.

Not sure where you got that from, maybe a quote or two would be handy.


To me there is a clear case for building a bike that is easier to ride, and handles better (like stick a tamer engine in an RS chassis)

There is no doubt about how impressivly Av cleaned up at Tokoroa and then again at Te Puke on her RS/GP125. The bike was prepaired by Chambers and based on TeeZee's work, the engine layout followed TeeZee's ideas posted earler.

I don't think anyone doubts that more hp in her hands will be devistating.

[F5 Dave]

I am wondering, how comes nobody has yet started to do "the ugly things", like welding cooling fins to a 125 gp barrel, or taken a powerful 125cc barrel, sleeving and destroking it to get below 100cc, or cast one's own cylinders (would that be allowed)?
. .
They are all supposed to be non competition parts, so not any 100cc, he meant 100cc could be water cooled. To that end we do weld water jackets to air cooled 100s if keen.