View Full Version : ESE's works engine tuner
Gigglebutton
4th May 2011, 18:52
looks like a big suck pipe with a shallow taper reverse cone?
You got it. An odd mix but works well for an average rider like me. No spike of power to try and ride on. Teezee has some ideas on how to get a bit more Hp and the ignition from Wobbly will help a whole lot. The current one has way to much retard up top. Still coughs up top:angry:
Just taken it for a ride. It picks up the front wheel in 1st gear off the throttle with no clutching. Did it in 2nd a couple of times ridding over bumps in the road :woohoo:
I will have to play with the setup next practice day
RMS eng
4th May 2011, 18:55
um, are you sure that isn't a std GP125 run you have transposed there by mistake?
peak power at 10,000 & above 10hp for 3,500rpm? Sheesh!
i know Dave it kills my RG50 dyno sheet,maybe its a 70,my RG50 made 11hp at 12400 and reved to 14000,and made 6.5hp at 9000,that thing makes 11hp at 9000.
Gigglebutton
4th May 2011, 18:58
What pipe is on that dyno run, looks as though it would make alot more power yet as something is making it sign off early???
Ignitions will be here any day.
I got it about 6 years ago. I think your wright a bit of a miss match. I want to build a full reed motor, so will get you to have a look at that when i have all the bits.
i know Dave it kills my RG50, mine made 11hp at 12400 and reved to 14000,and made 6.5hp at 9000,that thing makes 11hp at 9000.
Like yours, mine makes its most hp about 13,000 and revs to 14 before falling flat.
Still coughs up top .... :angry:
Some thoughts on the over rev cough...........
….. high rpm coughs between gear changes? sometimes they appear on bikes with tame, well, not radical inlet durations (piston port & rotary).
See this all the time in kart racing - reeds as well, usually its the needle/tube combo going lean as you pass thru 3/4 throttle, when backing off for the change.
Get an Ignitech on there and do full throttle shifts - easy.
Also happens when an engine is reved too far past peak power before a gear change. The airflow drops in the overev, the carb goes lean and it will backfire as the change is made ( even using a speedshifter). RS125 engines in karts do it with steep baffles, as soon as you rev them too hard.
Its not scavenging that’s directly the issue, its lack of blowdown time, that effects scavenging efficiency and delivery ratio. Means the cylinder is full of exhaust residuals, as much of the mixture waiting in the ducts is reverse flowed back into the case.
Jan Thiel
At high rpm there is some reverse flow, the transfer ducts becoming black, and even the crankcase and carburettor bellmouth because of the entering burned gasses. This happens because with raising rpm. the pre-exhaust flow (blowdown) becomes insufficient. When rpm raises still more there is no more transfer flow and the engine stops completely. So transfer flow depends completely from what is 'allowed' by the exhaust flow!
wobbly
4th May 2011, 19:58
Hey Giggle I think you are a little optimistic about the "useability" of the dyno curve.
The problem is that the front side of the curve is very angled upward, makes it look impressive, but the problem is that under racing conditions you will be short shifting all the time to stay in the fat part of the power.
This will inevitably mean low overall gear ratios and this will inevitably defeat the impressive hump of power, as whenever you get into the front side, small openings of throttle will give big increases in power over low changes in rpm.
The exact opposite of what is needed to ride fast.
The perfect rate of change in power is a straight line - so as you open the throttle, you get a linear change in power given.
Doing wheelies off the bottom may be fun, but actually makes it harder to ride fast, as only Pedrosa and Stroud can steer a bike easily with the front off the deck.
few interesting videos:
GP125 cylinder casting by Gnani
http://www.youtube.com/watch?v=I-2rJtnkYq4
http://www.youtube.com/watch?v=Lj4h9666d9s&feature=related
http://www.youtube.com/watch?v=A50p3cg90s4&feature=related
:corn:
That my friend, is GOLD. nice find...:woohoo:
shame it can't be downloaded; I'd just about put it next to my Britten VHS:love:
Gigglebutton
4th May 2011, 21:07
Hey Giggle I think you are a little optimistic about the "useability" of the dyno curve.
The problem is that the front side of the curve is very angled upward, makes it look impressive, but the problem is that under racing conditions you will be short shifting all the time to stay in the fat part of the power.
This will inevitably mean low overall gear ratios and this will inevitably defeat the impressive hump of power, as whenever you get into the front side, small openings of throttle will give big increases in power over low changes in rpm.
The exact opposite of what is needed to ride fast.
The perfect rate of change in power is a straight line - so as you open the throttle, you get a linear change in power given.
Doing wheelies off the bottom may be fun, but actually makes it harder to ride fast, as only Pedrosa and Stroud can steer a bike easily with the front off the deck.
Cheers Wobbly. The more i learn about 2 stroke tuning. the more realize how little i know. If nothing else at least it is a whole lot of fun.
GP Crank Assembly
The inlet side crank wheel is chamfered at 45deg so its less of an obstruction to the incoming fuel/air mixture.
237969
The original GP crank can take a beating and the rod/big-ends handle a lot of abuse and are even better if they have been kitted with later TS/TF rod kits that have slotted rods and silver B/E brgs.
237967
But the problem with the original crank is that the piston pin is only 14mm making it hard to get decent pistons. I fitted an original RGV250 rod kit to mine so I could have a 16mm piston pin and therefor a bigger range of pistons to chose from.
237966
I got my RGV rod kits by stripping down an old RGV crank, they worked great, I have since found some after market RGV rod kits to not be as good as the originals.
Fitting an RGV250 rod kit meant boring the B/E pin hole out to 22mm and facing off the thrust washer faces and the inside of the crank wheels 1mm for clearance.
237971
The balance holes are asymmetricall, one side is bigger than the other, I drilled this hole so that the counter balance was symmetrically even and 100% opposite the bigend. The final balance factor on this crank is 50%. After trying it, I think that 52-55 might be better.
237970
The crank was machined down so it had 2mm clearance every where, I am not sure that it helped but the extra crankcase volume and with the programable ignition it seems to have benefited the power spread. Plugging the crank reduced the crankase volume by 25cc, machining down the crank added 50cc to the case volume. Chambers measured the crank in both configurations using the Archimedes principle.
237977
Phenolic caged main bearings, Koyo 6205 and 6304 FG C4 max rpm in oil 15-17,000.
The brgs have been fitted so the open side of the cages face the oil feed holes. The phenolic cages are more reliable than the usual riveted cages which can fly apart under the inertial load of quick crank acceleration, like blipping the throttle.
None of the crank work helped much with power but it did improve piston choice and reliability. Chamfering the inlet side crank wheel and changing the balance factor was probably the most helpfull. The original balance factor is about 65% and seems better at 50-55 when running at 10-11,000 rpm.
Moooools
4th May 2011, 21:33
That my friend, is GOLD. nice find...:woohoo:
shame it can't be downloaded; I'd just about put it next to my Britten VHS:love:
http://mashable.com/2009/08/13/download-youtube-videos-to-desktop/
If it exists it can be fond on the internet...
Gigglebutton
4th May 2011, 21:36
i know Dave it kills my RG50 dyno sheet,maybe its a 70,my RG50 made 11hp at 12400 and reved to 14000,and made 6.5hp at 9000,that thing makes 11hp at 9000.
How long ago did you build your Rg? Aren't the Derbie's making 15 plus Hp? Ask why, don't assume
RMS eng
5th May 2011, 08:18
How long ago did you build your Rg? Aren't the Derbie's making 15 plus Hp? Ask why, don't assume
i think the derbi 50 s are around 14hp much more than 15hp from a 50 would be hard work at the kart track,ask Dave how much his RG50 makes,fast bike,but Mark on his semi stock Aprilia with maybe 12hp beat all the top 50s and 100s 2 years ago.your looks to be the best for the kart track but the RG50 frame will need work to get the most from it.
F5 Dave
5th May 2011, 10:24
He jumped the start!
Gee I thought I'd got over that:facepalm:
Mark on his semi stock Aprilia with maybe 12hp
very semi stock as thats approximately 50% more power than off the showroom floor
Fooman
5th May 2011, 13:56
The perfect rate of change in power is a straight line - so as you open the throttle, you get a linear change in power given.
Forgive me if I get this wrong, but doesn't that imply a flat torque curve (i.e. engine is operating at peak efficiency all the way through the rev range) as power is the integral wrt frequency of torque.
The new curve may not be perfectly flat, but it is certainly more efficient throughout more of the rev-range (except right at the top), and makes more power overall - the shift points will be lower than the higher-revving motor, but it won't be short shifting for that curve.
Gearing may have to lowered to take advantage of the power wrt to top speed, but the mid range should still be better than the original motor.
Big Bang RG50 anyone? Firing every 2π rather than every, er 360°???
FM
jasonu
5th May 2011, 15:22
He jumped the start!
Gee I thought I'd got over that:facepalm:
and you told me off for going on about my crank seal. (which you still owe me for...)
speedpro
5th May 2011, 16:18
and you told me off for going on about my crank seal. (which you still owe me for...)
Are you blaming crank seals for Taupo blowups??
Gigglebutton
5th May 2011, 17:32
i think the derbi 50 s are around 14hp much more than 15hp from a 50 would be hard work at the kart track,ask Dave how much his RG50 makes,fast bike,but Mark on his semi stock Aprilia with maybe 12hp beat all the top 50s and 100s 2 years ago.your looks to be the best for the kart track but the RG50 frame will need work to get the most from it.
The motor is designed for both F4 & F5. The 2 curves on the graph are the motor in its 2 different states of tune. F5 is not 11hp yet, Speedpro tells me 14hp is achievable . Time will tell. F4 is a very different state of tune. The motor will not last long like this but hopefully with a bit of help from the boys and not to many seizes we can get it to hang together. I have made a load of bits to get it to handle,Big brake,17'' rims, Rear height adjuster, Braced swing arm, Fork brace, Fork emulators, Not sure what to do with the rear shock yet. Trying to get it sorted before i give it to my daughter. I have bought an Rs roller for F4 in Aus but have to get it here some how.
Add a 1/2 throttle plate and the flow wont be as disrupted , as it would be with a plane "gate" when inserted.
238004
Could these SU carb parts be used along the lines that Wobbly suggested for my project to extend the lower rpm range of the GP by varing the inlet area and closing point .......... :scratch:
F5 Dave
5th May 2011, 18:20
The motor is designed for both F4 & F5. The 2 curves on the graph are the motor in its 2 different states of tune. F5 is not 11hp yet, . . ..
??? What do you mean by that???
So the blue line is not a 50 if it is for F4?
I struggled to see how you achieved a rear wheel BMEP of 165 from an RG
??? What do you mean by that???
:scratch: :whistle: :lol: about sums it up Dave.
You had me going too Giggles but I see it now, very nice!
F5 Dave
5th May 2011, 22:14
and you told me off for going on about my crank seal. (which you still owe me for...)
Didn't we trade that off for shots at Ohakune? Besides, you gave me that crank seal if I promised not to beat you in the GP the next day. And didn't.
Made you work for it though.
ac3_snow
5th May 2011, 23:07
Spent the evening nutting out my engine mounts, origional plan didn't quite line up the sprockets well enough. Started by making dummy mounts out of ply and checking it all lined up and had space where space was needed.
238011
I have used 12mm alloy plate along with 25mm alloy bar which I drilled out to fit a 10mm high tensile threaded rod. Hopefully I will get away with only the two engine mounts at the rear and not need to make a front mount point as well... (I did find an old post of yours TZ that you had an alloy mount crack at the BOB... what kind of alloy did you use? - by the time I read this I had already committed to using aluminum so will wait and see how long it lasts)
238012
Also while looking at the mounting problem last week I came across this little gem. Think the frame was in an accident at some point as the l/h foot peg has also dented the swing arm, that and a bit of bad welding in the first place perhaps.
238013
Hope to have a mate help me weld up the crack next week as well as welding the round bar to the alloy plate to help with strength(?) and ease of installation/removal.
Buckets4Me
6th May 2011, 06:13
(I did find an old post of yours TZ that you had an alloy mount crack at the BOB... what kind of alloy did you use? - by the time I read this I had already committed to using aluminum so will wait and see how long it lasts)
then mounts that we had crack and cause trouble are only related to the RS frames :facepalm:
we are using a radiator mount to hang the frount of the engine off :shutup::facepalm::shit:
238015this is my fix for the monting point. Ned kelly did it differently
Buckets4Me
6th May 2011, 06:16
238016here is TZ after he gave my poor little 50 a bit to much in the wet
238017but still rode to finish
238018I wonder why the caned his life insurance
wobbly
6th May 2011, 07:54
Dead right a flat torque curve gives a straight line power graph.
Here is sim of new F3 motor, RZ400 with around 120RWHp, near perfect throttle connection.
speedpro
6th May 2011, 13:01
I have used 12mm alloy plate along with 25mm alloy bar which I drilled out to fit a 10mm high tensile threaded rod. Hopefully I will get away with only the two engine mounts at the rear and not need to make a front mount point as well...
I used a flimsy mount at the front of my TS100 engined bucket and it vibrated very badly. Tying it solidly to the chassis fixed a lot of the vibration. My experiance says you will need a solid front engine mount to the steering head area.
jasonu
6th May 2011, 13:05
Are you blaming crank seals for Taupo blowups??
No, that was an act of god...
jasonu
6th May 2011, 13:10
Didn't we trade that off for shots at Ohakune? Besides, you gave me that crank seal if I promised not to beat you in the GP the next day. And didn't.
Made you work for it though.
Yes you did so beat me you 2nd me 3rd. That is why I am still harping on about it. My wife says I am obsessive but she says it like it is a bad thing....
F5 Dave
6th May 2011, 17:19
Did I? it was so long ago. Ok next time yer over in wgtn I'll buy you some beers:sunny:.
Heck I'll even extend that to Wanganui for the boxing day races.
Filled transfers as suggested by Wobbly.........
Copper fins and spacer plates.
Not sure if all this extra cooling is needed but if you are going to make a copper head gasket, it might as well add something to the cooling. Same with spacer plates, you could have a plain old alloy one, or one made up of fins that helps keep heat from the barrel getting to the crankcase and inlet tract.
In my engines I have been using flat top and concave pistons, and they easily allow the copper head gasket to be brought right into the combustion chamber to form a cooler running squish band. This could be done with domed pistons although it would be little more difficult getting the shape right.
By using a copper head gasket/cooling fin and an original composit head gasket the thermal barrier of the composit gasket and the extra cooling of the copper allows the head to run way cooler than the cylinder, maybe 60-80 deg C measured near the plug with the cylinder nearer a 100 after an outing around Mt Welly.
Ignitions....... The KX80 flywheel tapers fit the GP/TF/TS/RG crankshafts, the KX125 flywheel taper is too big.
238062 238064
Trangular KX80 stator fits with some shims to keep it central. This is a fixed point ignition where the timing is static and has been very successful for us.
238060 238061
The round KX80 stator needs some machining to make it fit, the inside needs opening out to fit over the main brg oil seal and the outside needs trimming a mm or so. There is some retard built in, so might not suit every one, but the trigger works well with the Ignitech and the HV charge coil can be re-wound for charging the Ignis battery.
238071
We never had much luck with these RM ignitions on our bikes. Spent hours on the dyno with the GP's and RG50's, never got good curves on our engines with them. Get them right at the bottom and they are over retarded at the top or right at the top and the bottom falls apart.
They are good ignitions but there is to much retard and in the wrong place for us, goes to show that a good curve for one engine might not suit another. The stator is a good looking piece of kit, replace the blackbox with something else or home made and they could be quite good.
238063
The SPARKER DC-CDI-P2 race Ignitech Ignition that we use, ava from Wobbly or Ignitech http://www.ignitech.cz/english/aindex.htm
I got the job of setting up NedKellys IgniTech programmable Ignition. This is how I went about it..........
Dead right a flat torque curve gives a straight line power graph.
Here is sim of new F3 motor, RZ400 with around 120RWHp, near perfect throttle connection.
Jesus H christ. That would fuck the 600s too.
Nice.
I drilled out to fit a 10mm high tensile threaded rod.
People have probably used it a lot in the past, but I would avoid threaded rod. If it does vibrate inside your mounts, the threads COULD (not saying it will) chew out the ally plates, or chew out the threads. If the latter occurs you are effectively left with about 8mm of steel rod.
I cut some threads on the ends of some 10mm 4140, to make some STRONG studs.
Actually I have about 4m of it left at work if anyone wants some.
speedpro
7th May 2011, 11:02
In my engines I have been using flat top and concave pistons, and they easily allow the copper head gasket to be brought right into the combustion chamber to form a cooler running squish band. This could be done with domed pistons although it would be little more difficult getting the shape right.
Easy. Anneal the copper, Assemble the motor without base gaskets. Try pushing it up and down the drive in gear - perfection.
Because a few people have asked about the GP engine, to save wading through 270 pages, these links go to the more relevent posts about the 27hp engine. Different link collections can be found on the decade pages 80-90-100.....260 etc.
238154 27rwhp 1978 Suzuki GP125
The basic details for 27rwhp from a 1978 Suzuki GP125 Engine and RS125 Expansion Chamber.
Cylinder Deck Height (Squish) 0.8mm.
Exhaust 25.8mm from top of cylinder, and opens 80deg ATDC for 200deg Duration.
Transfers 40.8mm from top of cylinder, and open 116deg ATDC for 128deg Duration.
Inlet port opens 145 BTDC closes 80 ATDC and is 45deg wide and inlet port opened to 30mm equivalent dia with 24mm carb.
Std 1990 Honda RS125 Pipe. The pipe is 40mm and the exhaust port is 36mm, we leave it as is and don't match the Ex port to the pipe.
Opening the rear transfers and flattening the port roof to 5 deg. Main std at 12 deg. Boost std at 55 deg, but all opening together.
Primary transfer pretty much std., secondaries and boost as wide as possible, Exhaust 75% of bore diameter. Dimensions of a Honda RS125 Pipe.
On page 200 there is a simpler 23 rwhp setup using a RG250 chamber modified to RM125 specs.
Suzuki GP125 engine and RS pipe in a Yamaha FZR 3LN 250 rolling chassis. Dimensions of the Honda RS125 Pipe.
Gluing the 27hp Engine Cases……
27hp Inlet Port…… Inlet port opens 145 BTDC closes 80 ATDC and is 45deg wide with the inlet port opened to a 30mm equivalent dia and 24mm carb.
GP Crank Assembly……. the problem with the original crank is that the piston pin is only 14mm.
Copper fins and spacer plates.
Not sure if all this extra cooling is needed but ………..
After 40+ dyno pulls at near 30hp the glue blocking the oiler holes is still there inside the piston..
Buckets original video clip showing some air/fuel mass appearing in the carbs bellmouth as the engine gets up onto the pipe. Also the fuel line seems to run out of fuel, the problem was cured by fitting a header tank made from a plastic filter.
Ignitions....... The KX80 flywheels fit the GP/TF/TS/RG crankshafts…..
The oiler holes for the exhaust bridge need plugging on most pistons so they can be used in the GP's. Normally I would weld them but was persuaded to try gluing them with some super duper stuff that’s as tough as shark shit.
After 40+ dyno pulls at near 30hp the glue blocking the oiler holes is still there inside the piston.......
Old RS piston with bridge oilers glued up........
Ballance Factor in % is A/B * 100
27rwhp cylinder, Cylinder Deck Height (Squish) 0.8mm……..
CCing the Cylinder Head ........ looking for 13.5 - 14.0 to 1 compression ratio, thats about 9.75 - 10cc clearance volume in the head.
Early Honda RS Pipe ...........
BF=(A/B)*100
A is the flywheel counter balance weight and B is the reciprocating mass (weight).
238097
The lower half of the rod and big end can be considered rotating mass and disregarded and the upper half and little end reciprocating mass, along with the complete piston assembly.
Ballance Factor in % is A/B * 100 and is the amount of reciprocating mass counter balanced by the flyweel counter balance weight.
238096
Finding "B" the reciprocating mass. 231.9g
238095238098
Finding "A" the flywheel counter balance mass. 73.4g
In this example BF = (73.4/231.9)*100 = 32%
A will need to be 231.9 * 0.55 = 127.5g for a balance factor of 55%
238099
Adjusting "A"
This crank needs some mass added to the flywheel counter balance and this is being done here by removing mass from around the pin, and that effectivly makes the counter ballance heavier.
Looking at the connecting rod it is easy to see that the Big End goes round and round and is all rotating mass. And the little end goes up and down and is all reciprocating mass.
Pic-1 shows the crankshaft divided into "Rotating Mass" on the left and "Reciprocating Mass (weight)" on the right………….
There has been a lot posted on ballance factors, you can use "Thread Tools" / "View Images" to find them.
27rwhp cylinder
Cylinder Deck Height (Squish) 0.8mm.
Exhaust 25.8mm from top of cylinder, and opens 80deg ATDC for 200deg Duration, 75% of bore diameter.
238136
Transfers 40.8mm from top of cylinder, and open 116deg ATDC for 128deg Duration.
238139
Mains left std with the port roof angled up 12 deg. Boost std at 55 deg, and all opening together. Primary transfer pretty much std., secondaries and boost as wide as possible.
Wobbly suggests having the secondry transfers opening 0.5-1mm after the mains. He also points out that the port that opens first, flows last as the residual gases in the cylinder pushes down into the transfer duct before there is enough vacuum in the cylinder to allow the transfers to flow.
238137 238144
Opening the rear transfers and boost port. Flatten the port roof of the rear transfers to 5 deg and leave the boost at 55.
238141
The copper under the exhaust port is to quickly transfer heat from this area to the copper under cylinder cooling fins.
The copper fins get realy hot, and that is heat from the exhaust port that is not getting into the cylinder and the rest of the motor, with this copper, the cylinder and cases run cooler.
The copper is a bit optional, the real performance comes from opening up the rear transfers and boost and increasing the blowdown time area by rasing and widening the exhaust port.
238145
Don't forget to leave ring friendly radiuses in the corners of the exhaust port like this Aprilia. The Suzukies single exhaust port limits blowdown-time-area and power. For the Suzuki GP to make any power the secret is to keep the transfers as low and wide as possible and up the area of the exhaust port that is above the transfers.
CCing the Cylinder Head ........ looking for 13.5 - 14.0 to 1 compression ratio, thats about 9.75 - 10cc clearance volume in the head.
CR = (CV+SV)/CV
Compression ratio = Clearance Volume plus Swept Volume all divided by Clearance Volume
238148
We use car anti freeze and 5 and 3 cc syringes. Plastic syringes can be brought from the Chemist.
238146
With the volume in the copper head fin and concave piston measured we only needed 6cc in the head itself.
238147
Piston at TDC and a light smear of grease to seal things, the clearance volume was measured. It took a few skims in the lathe to get it right but in the end it was spot on.
F5Dave mentioned he takes the level up to the second thread (I think ) in the plug hole to take account of the volume inside the spark plug. If your running a 50 or even a 100 or 125 small volumes like the inside of the spark plug matter.
238149
Works a treat.
Early Honda RS Pipe ...........
238151
The early RS pipes can be made to fit on the Suzuki GP realy easily. The original flange needs cutting off and another made, I used the one off the original Suzuki GP pipe.
The Suzuki exhaust port is 36mm and the RS pipe is 40mm, we don't match them up, we leave the step, we think it helps attenuate (hold up) the return pulse and broaden the power spread a little. Who realy knows, but Honda have a similar step in their RS barrels.
238150 238152
The mid section needed cutting and turning. We used braze on this as it copped with the old oil better than the tig, also the copper is a softer join with more "grip area" so less likely to crack.
238153
The RS pipe dimensions if you want to make one of your own. The venturie at the end of the reverse cone means you don't have to worry about the length and diameter of the stinger. With a blead down venturie, make the stinger diameter bigger and its removed from the resonant equation and then just becomes an exhaust pipe.
wobbly
8th May 2011, 16:32
You should cut the plug surface such that the unthreaded end of the plug body protrudes 0.5mm into chamber.
With a 10 range plug, then the vol to top of the plug hole is exactly 2.2cc bigger than the chamber.
I use ATF in a burrette, no grease on the bore as you want to measure the above ring crevice vol as well.
Find tdc, then drop the piston a small amount - fill the vol to 1/2 way up the threads, move the piston up/down, till fluid sits the highest,then fill to top.
Leave the burrette sitting for 5 mins as the fluid left on the glass walls slowly runs down.
While this is happening you can take off the head and clean things out.
50bucketracer
11th May 2011, 09:41
I’m not a regular on this forum but do have the occasional read. I note that this thread (& some others) have made the occasional reference to my Derbis. So I thought some of you might be interested in a bit of background. Its a long post, so pass over if you have a short attention span...
Bucket racing for me began in 1987 with an MB50 at Ohakea. I moved to Auckland in 1989 & then replaced the MB50 with an RG50, then fitted a TS100 engine into another RG50 frame in 1992 to race F4 as well. The RG50 was replaced by a TZR50 in 1992, & the RG-TS100 was replaced with an MB100 in a TZR50 frame in 1996.
I have always done my own 2-stroke motor work (outsourcing some welding & machining – mainly to RMS engineering) & first went near a dyno in 1996. My TZR50 made 14 RWHP & my MB100 made 25 RWHP on a Dynojet 100, & that was 15 years ago! I kept racing both those bikes for around 10 years, but in 2005 fitted a Derbi 50 motor into the TZR frame. This still only made the same 14 RWHP, but I did succeed in giving it a better mid-range. Meanwhile I had detuned the MB100 to 20 RWHP in a futile attempt to make it easier to ride round the Mt Wellington kart track...
In 2005 I managed to push through the rule change to allow 150cc 4-strokes, changing the face of buckets by allowing hoards of FXR diesels into the class (& probably saving it from extinction!). Meanwhile I had slotted an FXR150 motor into the trusty TZR frame. This only made 18 RWHP on the dyno, but because the power/torque spread was so wide, it was just as fast as the MB, at least on a kart track, & especially in the wet. By then was also getting tired of replacing cracked crankcases on the MB. From this time on the only dyno I have been near is John Connor’s. I understand he has calibrated it against a Dynojet, but I’m not 100% sure how equivalent they are.
But the diesel did not prove as reliable as I’d expected (over-rev big-time blow-up on the dyno, broken rod & failed big-end all cost a lot more to fix than the good old 2-strokes). So I decided to go back to a 2-stroke & eventually settled on up-sizing the Derbi 50. It is available as a 70 or 80 in some markets, & while 80cc (actually 78cc) is well short of the 104cc class limit (& not much more than half the 130cc air-cooled limit), a modern motor design should go some way to making up for its lack of cubes, plus its light, more reliable & parts are not expensive. Given the potential legality issues with after-market parts, I made sure I used only motor parts (other than ignition, carb & pipe) made for road use. I chose a street Malossi 50mm cylinder (not the alternate MHR team cylinder also available) to go with the 40mm crank. I bought my 1st motor from Corsa wreckers in Mt Wellington. It was already 70cc, but Rick also had a Malossi 80cc cylinder available so I bought that as well. Without going into too much detail, I kept the port timing mild (132 transfer & 193 exhaust) to ensure it would be rideable around a kart track & then shaped the transfers & exhaust to mimic a Honda RS125. Ignition is PVL & carb Keihin PWK28.
This initially made the same 18 RWHP on John Connor’s dyno as the FXR had, though obviously way less mid range torque. In that form my then 15 year old son Nathanael did 1m26 sec lap at Taupo to qualify on pole for the 2009 GP. It was only his 2nd ride on the 80 (I was out that year with a broken back). Unfortunately the new piston I had fitted before the meeting broke on the 1st lap of the GP – it turned out to be the wrong part! For 2010 some refining of the porting increased the output to 20 RWHP, plus I build a 2nd 80 with a few improvements that made 24 RWHP. However the jetting for that run was too lean & it seized in its next race, damaging the bore. I doubt it makes more than 23 RWHP currently. We had high hopes for the 2010 GP, & while we went well in dry practice, unfortunately our carb settings did not suit the weather conditions on race day. A rich needle meant that both motors flooded on closed throttle & often took several seconds to clear after each corner. We (well at least me) must have looked like right amateurs racing down the straights, then costing for 10m or so after each corner while we tried to get them firing again. Nathanael managed far better than I did. Unfortunately I had no time to sort this prior to the race as my motor had popped a crank seal at the end of practice & it took me ages to diagnose & fix. I completely missed qualifying & only got it back together just before the race. Roll on the 2011 GP, though by then there may be a grid full of 30 RWHP buckets to compete with!
Looking back over 25 years of bucket racing, in F5 my best national GP result on the RG was 2nd, on the TZR 1st, also 1st on the TZR-Derbi & 1st on the RS-Derbi. In F4 my best national GP result on the RG-TS100 was 4th, on the TZR-MB100 2nd 3x, on the TZR-FXR150 2nd twice. I’m still waiting for that elusive F4 GP win (which is looking increasingly unlikely given that I turn 52 this year).
50bucketracer
11th May 2011, 10:09
As a follow-on, I have been contacted by the guy I sold my son’s Metrakit GP50 to. He has moved overseas & wants to sell the bike. A bit of a shame as he never even raced it. But in Googling the bike to see if I could find the old Trademe listing (to save him having to do the research again), I found some postings on this site that questioned the legality of this bike. Even though I don’t own it anymore, I thought I should clear that up. Metrakit make a range of purpose built race bikes. Almost all of them use race modified Derbi or Aprilia motors. However the base model uses a bog standard street 50cc motor, in this case a Derbi. It still has the standard Derbi ignition & tiny 13mm carb. All internal parts are bog standard, only the pipe has been upgraded. So even though the chassis is a dedicated race item, the motor is not. It only makes 10-11 hp & is absolutely legal for buckets in NZ.
In a similar vein, the Yamaha TZR50 I raced a few years back is also a genuine street bike, that comes complete with lights etc etc. Again absolutely legal for F5. Many people confuse it with its sister TZ50, which is the race version of the same bike. There are a few of these in NZ & by the letter of the law they are illegal because they are a purpose built racer. But in my view it is a somewhat grey area in that the street TZR & race TZ are almost identical. I have the parts books for both bikes & most parts, & even most motor parts are identical. The pipe, carb & ignition are different, but almost all internal motor parts are identical – nothing that would give an unfair advantage. You’d have to be pretty observant to spot the difference & you’d have to have pretty rigid views to exclude the TZ from racing.
To be honest with the number of F5 bikes running at the moment I'd say you'd have to be insane to exclude anything that fell into a grey area.
On a more positive note I know of a couple of F5 builds going on at the moment so maybe there will some sort of class resurgence.
Also, if anyone knows of an RG50 for a resonable price let me know, I got hooked after riding Cullys.
I note that this thread (& some others) have made the occasional reference to my Derbis. So I thought some of you might be interested in a bit of background.
:clap: :clap: Nice one Dave.
Have you based your porting changes on time area or is it more about duration and angles?
F5 Dave
11th May 2011, 12:30
Good post Dave, good to hear your point of view here. Forums can get somewhat distorted.
As a side note; what markets have had Derbis released as 70s or 80s? Do you mean released by Derbi as a new road bike? Or you mean the kit parts have been released?
Dave was a great help to me back in the late 80s with a pipe design for my MB50 which helped match & then some the brand new RG50s that had appeared on the scene. There had been some muttering at the time that the RGs were like cheating as they cost $1700 new & there was talk that buckets should be 7+ years old. As it turned out they got cheap quickly (I didn't buy mine until it reached $400) & they single handedly (if that's even a real word) saved the F5 class. Sounds a bit familiar.
If Dave added the list of Auckland race wins/club champs/2hrs to his resume it would take the next few pages.
Gigglebutton
11th May 2011, 16:45
Thanks Dave. I hope to give my Rg50 to Georgie, when i get it sorted and build a F4 bike. I have been talking to Wobbly about F5 motors and which one to use. He mentioned the Derby , but making a 100cc motor from one. Looks like it could be harder to get 30hp from one than we first thought
Gigglebutton
11th May 2011, 16:51
To be honest with the number of F5 bikes running at the moment I'd say you'd have to be insane to exclude anything that fell into a grey area.
On a more positive note I know of a couple of F5 builds going on at the moment so maybe there will some sort of class resurgence.
Also, if anyone knows of an RG50 for a resonable price let me know, I got hooked after riding Cullys.
I have Dave Mullins old Honda 50 on loan for Georgia to try. Its very standard, but if i can get it running you are welcome to ride it until she decides what she is going to ride
If this rain stops !!!!!!!!
jasonu
12th May 2011, 13:18
I have Dave Mullins old Honda 50 on loan for Georgia to try. Its very standard, but if i can get it running you are welcome to ride it until she decides what she is going to ride
If this rain stops !!!!!!!!
Dave Mullins is a name I haven't heard for years and he is a top bloke!!!
Gigglebutton
12th May 2011, 21:42
Dave Mullins is a name I haven't heard for years and he is a top bloke!!!
Hes a great bloke and good mechanic. Lent me his bike and a Derby barrel to look at :yes: He may be at the track on Saturday taking photos in the morning
TZ350
13th May 2011, 12:12
I am hoping this V Tech inlet idea will add an extra 1000 or so rpm on the bottom end to beat those FXR's in the power spread stakes. Blue line, GP125 2-Stroker Red line FXR150. The idea is that at low rpm, the half butterfly closes, the area of the inlet tract is smaller and the rotary valve closes earlier, thereby increasing low end drive, hopefully from 6-7,000 rpm.
F5 Dave
13th May 2011, 12:40
Unless it's virtually touching the disc I doubt you will see an improvement, but II like your thinking. How abut a YPVS controlled guillotine at the disc face. That would be hard to engineer but give clear results?
TZ350
13th May 2011, 17:01
Unless it's virtually touching the disc I doubt you will see an improvement, but II like your thinking. How abut a YPVS controlled guillotine at the disc face. That would be hard to engineer but give clear results?
I have thought about a guillotine at the rotary valve face like you suggest, but found it hard to impliment, so chose this method which also has the benifit of a bit of length to the reduced inlet tract for some ram effect and other benifits like increased crank case volume at low rpm for extra low end torqe.
My original drawing shows the divider extending to the rotary valve face, the half butterfly was a refinement suggested by Wobbly. I realy hope this works, then we could have powerfull and easy to ride 2-strokers.
F5 Dave
13th May 2011, 17:54
if only there was some way of providing a constantly variable intake timing solution to the inlet of a 2 stroke that suited the engines demand. Perhaps based on a wind instrument technology. I think I'll call it Torque Induction.
To the patent office!
Yow Ling
13th May 2011, 18:53
if only there was some way of providing a constantly variable intake timing solution to the inlet of a 2 stroke that suited the engines demand. Perhaps based on a wind instrument technology. I think I'll call it Torque Induction.
To the patent office!
Torque induction , sounds like some clever way to induce labour. Now there is a variable intake tract to base future innovations on.
TZ350
13th May 2011, 19:02
if only there was some way of providing a constantly variable intake timing solution to the inlet of a 2 stroke that suited the engines demand. Perhaps based on a wind instrument technology. I think I'll call it Torque Induction. To the patent office!
.................... :facepalm: .......... :bleh:
Torque induction , sounds like some clever way to induce labour. Now there is a variable intake tract to base future innovations on.
................... :)
sonic_v
13th May 2011, 20:08
Another method that has been used before is two intake ports and two carbs with staggered throttle opening. This also allows you to run different intake lengths and even carb bores. See Cesare Bossaglia book from early 70's for some photos of kart engines running this set up.
My father in late 70's converted a 125 air cooled disc valve engine to this setup that ran very sweet and had a lot of race wins.
TZ350
13th May 2011, 21:08
Giant list of books about the two-stroke cycle engine/ Two-Stroke motorcycles:
While searching for Cesare Bossaglia book that Sonic_V mentioned, I found this great books list on http://www.2strokeworld.com/forum/index.php?topic=2022.0
Tuning the Two-Stroke Motorcycle
by Motorcyclist Mini-Manual
Publisher: Peterson Publishing Co.
Pub. Date: 1973
ISBN: NA
64pp
Souping Two-stroke Engines for More Power and Speed (Pamphlet)
Publisher: Floyd Clymer Publications
Pub Date:1954
ASIN: B00124WLVE
46 pages
Two-Stroke Ports for Power
by Roy Bacon
Publisher: Lodgemark Press Limited
Pub. Date: 1968
ISBN: NA
52 pp
Two-Stroke Carburetion and Ignition
by RoyBacon
Publisher: Lodgemark Press Limited
Pub. Date: 1970
SBN: 850770084
51 pp
Two-Stroke Exhaust Systems
by RoyBacon
Publisher: Lodgemark Press Limited
Pub. Date: 1967
ISBN: NA
47 pp
Rotary Valve Two-Stroke Engines
by Alan T. Burgess
Publisher: Lodgemark Press Limited
Pub. Date: 1971
SBN: 850770211
104 pp
Two-Stroke Motorcycles and How to Get the Best From Them
by staff of Motor Cycle
Publisher: Floyd Clymer
Pub. Date: 1967
ISBN: NA
138 pp
Improving Two-Stroke Engine Performance
by J. W. Vierdag
Publisher: Floyd Clymer
Pub. Date: 1967
ISBN: NA
126pp
Tuning Your Two-Stroke Engine, Motorcycles, Go-Karts, Outboards, Lawnmowers, Etc.
by K.G. Draper
Publisher: Coles Publishing Company
Pub. Date: 1977
ISBN: NA
125 pp
Two-Stroke High Performance Engine Design & Tuning
by Cesare Bossaglia
Publisher: Lodgemark Press Limited
Pub. Date: 1972
ISBN: 0850770289
227 pp
The High-Speed Two-Stroke Petrol Engine
by Philip H Smith
Publisher: Whitefriars Press Ltd.
Pub. Date: 1968
ISBN: NA
423 pp
The Two-Stroke Engine Design and Tuning
by KG Draper
Publisher: G.T. Foulis & Co. Ltd.
Pub. Date: 1973 5th ed.
ISBN: 0854291571
128 pp
Two-Stroke Tuning
by Roy Bacon
Publisher: Transport Bookman Publications
Pub. Date: 1981
ISBN: 0851840396
127 pp
Motorcycle Tuning Two-Stroke
by John Robinson
Publisher: Butterworth-Heinemann
Pub. Date: 1994
ISBN: 075061806X
169 pp
Two-Stroke Performance Tuning
by A. Graham Bell
Publisher: Haynes Publishing
Pub. Date: 2nd Ed.
ISBN: 9781859603193
271 pp
The High-Performance Two-Stroke Engine
by Dr. John C. Dixon
Publisher: Haynes Publishing
Pub. Date: 2005
ISBN: 1844250458
290 pp
Two-Stoke Power Units, Their Design and Application
by P.E. Irving
Publisher: Hart Publishing Company
Pub. Date: 1968
ISBN: NA
288 pp
Two-Stoke Tuners Handbooks
by Gorden Jennings
Publisher: H.P. Books
Pub. Date: 1973
ISBN: 0912656417
156 pp
The Two-Stroke Cycle Engine, Its Development, Operation and Design
by John B. Heywood and Eran Sher
Publisher: SAE International
Pub. Date: 1999
ISBN: 1560328312
451 pp
The Basic Design of Two-Stroke Engines
by Gorden P. Blair
Publisher: SAE international
Pub. Date: 1990
ISBN: 156910089
672 pp
Emissions From Two-Stroke Engines
by Marco Nuti
Publisher: SAE internationl
Pub. Date: 1998
ISBN: 076800215X
283 pp
Scavenging of Two-Stroke Diesel Engines
by Paul H. Schweitzer
Publisher: The Macmillan Company
Pub. Date: 1949
ISBN: NA
265 pp
Design and Simulation of Two-Stoke Cycle Engines
by Gordon P. Blair
Publisher: SAE International
Pub. Date: 1996
ISBN: 1560916850
623 pp
Two-Stroke Engine Theory and Diagnostics
by Yamaha Motor Company
Publisher: Yamaha Motor Company
Pub. Date: 1998
ISBN: NA
28 pp
Three T’s for the Two-Stroke, -Theory, Trouble-shooting, -Tuning
by Yamaha International Corportation
Publisher: Peterson Publishing company
Pub. Date: 1969
ISBN: NA
33 pp
SAE Technical Paper Collections:
Two-Stroke Cycle Spark-Ignition Engines PT-26
Publisher: SAE International
Pub. Date: May 1982
ISBN: 0898831148
ISBN-13: 978-0898831146
457pp
Advances in Two-Stroke Cycle Engine Technology PT-33 by (SAE technical papers)
Publisher: SAE
Pub. Date: Jun 1989
ISBN-10: 0898831202
ISBN-13: 9780898831207
485pp
Advanced Two-Stroke Engines PT-942
Publisher: SAE International
Pub. Date: March1993
ISBN: 1560913274
ISBN-13: 978-1560913276
171pp
Progress in Two-Stroke Engines and Emissions Control
Publisher: SAE International
Pub date: March 1996
ISBN-10: 156091761X
ISBN-13: 978-1560917618
158 pages
Two-Stroke Engines: Technology and Emissions
Publisher: SAE International
Pub date: December 1998
ISBN-10: 0768001269
ISBN-13: 978-0768001266
706 pages
speedpro
13th May 2011, 22:56
Unless it's virtually touching the disc I doubt you will see an improvement, but II like your thinking. How abut a YPVS controlled guillotine at the disc face. That would be hard to engineer but give clear results?
A splitter could be run from the butterfly shaft back to the disc valve then you would better reduce the opening of the disc valve port. As F5 points out, all the valve is doing at the moment seems to be reducing the area of the port. The disc valve timing wouldn't seem to be altered.
TZ350
13th May 2011, 23:50
A splitter could be run from the butterfly shaft back to the disc valve then you would better reduce the opening of the disc valve port. As F5 points out, all the valve is doing at the moment seems to be reducing the area of the port. The disc valve timing wouldn't seem to be altered.
Its a work in progress, the splitter was shown in the original drawing. The half butterfly instead of the gate was a refinement suggested by Wobbly.
238826
Bucket and I will hopefully get to finish the V Tech inlet next week and run it up on the dyno later.
gatch
14th May 2011, 16:08
Would it be possible to use two disc valves in unison ?
One being fixed to the shaft, the other floating next to the fixed disc. With a mechanism to "advance or retard" it at varying rpm..
With the theory that the floating disc could rotate to reduce the port area at low rpm etc..
Or even make the port in the case variable ? With say a similar set up to a carb ? That opens as the revs increase..
TZ350
14th May 2011, 17:13
give me a break Kelly,this thing needs to go to the track to see what it can do and if it will last a days racing.
Thanks to Kel and Gigglebutton for giving it a good run and their feedback.
I know it was only practice, but the engine proved itself and lasted all day, and it drove pretty much like you would expect it too, phat, but the bike needs some good tires and suspension setup to make it a real weapon.
Before we race and risk breaking it, there are a few things I wan't to do, like dyno the V Tech inlet and try water injection to go with it, then there is the electric power jet carb. And most importantly, get the suspension sorted and a spare set of wheels with wets.
Gigglebutton
14th May 2011, 17:54
Sorry for dropping your bike Rob:bash: I have to say FUCK Yeah!!!. It is amazing. Sooo phat and it seams to have no end to the amount of revs you can pull. 1 gear up and 1 gear down round Mt Welly. You can short shift in the sweeper and drive out with that massive torque. Clutch it and it goes into "Warp Drive" Get the handling sussed and it could be a GP winner. Cheers mate, Dazz
TZ is looking a bit pale after Giggles had sent the bike down the track so I get the "just take it easy we're not sure about the tyres" talk before I’m let loose. I ease around the left hander onto the short back straight and effortlessly blow by 3 bikes, get into the sweeper short shift and then open the throttle and let it wind up, holly crap what a rocket! The dyno runs show the GP producing 85% more power than my FXR well it feels more like 200%!
The objective was to ride the GP like the FXR i.e. only using 2 gears, the bike certainly felt capable but with lack of familiarity I was hesitant to try and set any kind of pace. I come back into the pits and after adjusting tyre pressures jump back on the GP with the conviction of doing a couple of reasonably quick laps but when I up the pace it starts pushing the front end. Not to be deterred I go harder then its pushing the front and sliding the rear. The rear end breaking loose is fantastic but the front end is starting to worry me and that little voice inside my head is saying "hey it’s not your bike don’t break it", shame the voice wasn’t speaking to Giggles :shutup:. The bike has also developed a delay in coming back on the throttle so I reluctantly take it back to the pits.
So the verdict - Firstly I didn’t do the bike justice but it sure was fun. The power is wide and smooth and when its moving its really moving. With a decent set of slicks, a good rider and some dialling in the GP has the potential to win many races. I certainly wouldn’t want it behind me on the final run to the line.
TZ, Vee rubber slicks? :oi-grr:
Have you guys measured up the RS125 pipe?
TZ350
16th May 2011, 21:40
Have you guys measured up the RS125 pipe?
239122
We haven't measured ours, but I found this on the net ........... page 270 has a lot of other info too.
239122
We haven't measured ours, but I found this on the net ........... page 270 has a lot of other info too.
Ahh, Shit it was right in front of me!
Cheers, I'm just working over pipe designs and stuff, I've grafted a new one on but its still a heavy road pipe, I would like to make a lighter one soon. Still have much other stuff to do on the bike yet!
TZ350
17th May 2011, 17:12
Cheers, I'm just working over pipe designs and stuff..........
The maths for Blairs pipe designs are on page 200, for anyone who likes that sort of stuff.
XL spreadsheet for the basic design of an expansion chamber, based on Blairs work ........... The spread sheet...... 223667
I find the header section the hardest to make, page 200 shows the header section of a RG250 pipe being re used so only some new straight cones are needed to finish the pipe.
TZ350
17th May 2011, 17:22
Making progress with my variable V Tech inlet tract and timing. Fitted the divider tonight and bolted it all up.
The plan is to run it up with the valve fully open then fully closed, compare the graphs and manually switch it during a run to see what a dual curve looks like. I am ready to go, just need to get to the dyno.
Hopefully it lasts long enough to see if it has any merit and nothing catastrophic happens, like the divider coming loose and getting caught in the rotary valve.
are you building a variable timing system?
bucketracer
17th May 2011, 19:53
are you building a variable timing system?
TeeZee's inlet idea is like the V Techs dual cam timing, with the rotary valve closing 55 deg ATDC at lower rpm and 85 deg at higher rpm. The size of the inlet tract and hence gas velocity also varies and its hoped both things together will allow the engine to pull well and cleanly from lower rev's.
Last Sat it ran pretty well around Mt Welly using just 2 gears, but TeeZee could see it was blowing back a bit through the carb when Kel was pulling out of the hair pin. With the V Tech inlet TeeZee hopes it will pull cleanly out of the slower corners and with its great top end run from corner to corner without losing time having to change gears and a zing on the clutch will launch it out of a tight spot or enable it to dive under someone if they let the slightest gap open up.
Anyway Ivan that's how I understand it from what Ive heard them talking about here at work.
I find the header section the hardest to make, page 200 shows the header section of a RG250 pipe being re used so only some new straight cones are needed to finish the pipe.
Yeah!
Ive got an OK Pipe but its a double skinned roadbike one. I weighed it tonight and it totals 8KG!
I thought I would get the rest of the engine sussed and play a bit, maybe with some different road pipes and shapes and when I have it finalised make a final pipe out of nice light and thin stuff and hope the heat difference doesn't change things too much.
I made this 239175 Scatter plot in excel to give a visual depiction of the differences between a few pipes.
It isn't all that accurate but I may slowly refine it.
Note the steep angle of the RS125 baffle.
Buckets4Me
17th May 2011, 22:35
when I have it finalised make a final pipe out of nice light and thin stuff
not to thin as this is for a bucket and they spend a fair amount of time on there side :facepalm:
wobbly
18th May 2011, 10:16
That old Honda pipe mod drawing is completely useless, it was never used by the factory in any form.The rear cone is insanely steep.
And the so called A Kit pipes were designed to work with high Ex ports - where the customer engines all had 83*ATDC to let them rev without an electric powerjet.
I have much better designs with a ton of dyno time on them, but of course they are all specific to 50Hp 125 cylinders, not 30Hp 100cc designs.
Here is one that has won dozens of 125 kart titles, but again it should just point you in the right direction for the 100.
jasonu
18th May 2011, 11:46
Making progress with my variable V Tech inlet tract and timing. Fitted the divider tonight and bolted it all up.
The plan is to run it up with the valve fully open then fully closed, compare the graphs and manually switch it during a run to see what a dual curve looks like. I am ready to go, just need to get to the dyno.
Hopefully it lasts long enough to see if it has any merit and nothing catastrophic happens, like the divider coming loose and getting caught in the rotary valve.
Is that a foam filter in the 1st pic? Be sure to dyno with and without it. I found that any sort of filter or mesh screen cost hp.
TZ350
18th May 2011, 15:43
Is that a foam filter in the 1st pic? Be sure to dyno with and without it. I found that any sort of filter or mesh screen cost hp.
239233 239237
No, not a filter, its a wind sheld to stop the wind blowing directly across the open bellmouth and upsetting the carburation. Also in the event of a crash it folds over the bellmouth and hopfully stops realy large rocks being sucked in.
wobbly
18th May 2011, 16:10
Here is the A Kit spec RS125 pipe drawing.
Nice so the valve shuts off at low RPM causing it to change the Inlet port sizing and not overfuel it at low revs? then when you accelarate past a certain RPM it opens right up?
Just guessing ti doesnt have the Vtec sound of the BOOOWWWW then 6k DAHHHHHHHHHHHHHHHHHHHH
I had a 2.2 litre Dohc Vtec Prelude thing was insane!
not to thin as this is for a bucket and they spend a fair amount of time on there side :facepalm:
Yeah, I'm quite keen to tuck it out of the way so it would take a colission or real nasty ding to dent it.
That old Honda pipe mod drawing is completely useless, it was never used by the factory in any form.The rear cone is insanely steep.
And the so called A Kit pipes were designed to work with high Ex ports - where the customer engines all had 83*ATDC to let them rev without an electric powerjet.
I have much better designs with a ton of dyno time on them, but of course they are all specific to 50Hp 125 cylinders, not 30Hp 100cc designs.
Here is one that has won dozens of 125 kart titles, but again it should just point you in the right direction for the 100.
You are always full of useful info, cheers.
hopfully stops realy large rocks being sucked in.
Always a Bonus!
Here is the A Kit spec RS125 pipe drawing.
As above
TZ350
19th May 2011, 18:03
239304
Ok.... got the V Tec variable inlet onto the dyno.
239305
The V Tec (Blue line) did not improve the low end torqe like I had hoped but it also did not knock back the top end either, and I will be able to tickle out the last bit by fiddling with the ignition.
239306
FXR Green line, so I did not get any more torque and only a little more spread at 6,000 rpm. So the FXR's are safe for now.
The big thing is that the V Tec cleaned up the throttle and got rid of the spit back in the 3-7000 range and makes the bike a whole lot more ridable, that in itself makes it worth while and a keeper if I can figure out how to open and close it on the fly.
Now to fit the V Tec divider securly and try water injection to hopefully get some FXR beating low end.
The big thing is that the V Tec cleaned up the throttle and got rid of the spit back in the 3-7000 range and makes the bike a whole lot more ridable, that in itself makes it worth while and a keeper if I can figure out how to open and close it on the fly.
Now to fit the V Tec divider securly and try water injection to hopefully get some FXR beating low end.
Use the power output from the ignitec to drive a RC servo (RC plane servo; should have enough torque for what you want) you might require a voltage divider as most are 5v.
Looking forward to the water injection.
TZ350
20th May 2011, 08:00
Use the power output from the ignitec to drive a RC servo (RC plane servo; should have enough torque for what you want) you might require a voltage divider as most are 5v.
Good idea Bert, much better than the electric door lock I was thinking of. The 5V should be easy, I can run the 12V output from the Ignitech through a TO220 5V regulator chip, easy.
I don't know much about RC servos, how are they controled? power on to turn, then off to stop? reverse polarity to change direction? Or is there different terminals for forward and reverse?
Looking forward to the water injection.
As soon as the inlet divider is secured properly we will try water injection, Thomas has some ideas for a Ram Tube and then there is the Slippery Pipe.
Buddha#81
20th May 2011, 08:14
With all this extra "stuff" going onto the inlet, when are you going to run out of ground clearance? Also there is alot of engineering and cost if you drop it on the r/h side. Is it worth it if you smash all that off on a cold track in practice at the start of the day and miss the rest of the meeting? Or do you have a ESE fix......hinged inlet manifold?
I understand this is part of the 30hp development but was on my mind for when it leaves the dyno and "hits" the track.
F5 Dave
20th May 2011, 09:35
. . .
FXR Green line, so I did not get any more torque and only a little more spread at 6,000 rpm. So the FXR's are safe for now.
. . .
So how far is it between each gear change? Do you really need a spread wider than it is? I mean it should just totally murder an FXR. It has more power than the coal burner for 4 &1/2 thousand rpm.
Why are you chasing this 2 gear changes each lap idea? Are you really loosing that much time throwing in a couple of extra changes? I can't see it. Gearing markedly changes the mechanical advantage at the rear wheel. Why go out of the way to negate it? I mean you're not driving a Chevy Nova.
TZ350
20th May 2011, 11:13
With all this extra "stuff" going onto the inlet, when are you going to run out of ground clearance? I understand this is part of the 30hp development but was on my mind for when it leaves the dyno and "hits" the track.
Yes it is getting a bit wide, but I figured I would try out all the ideas, keep the best, and then tuck what works out of the way somehow.
Do you really need a spread wider than it is? I mean it should just totally murder an FXR. It has more power than the coal burner for 4 &1/2 thousand rpm.
Yes, at Taupo it should murder FXR's easy.
Why are you chasing this 2 gear changes each lap idea? Are you really loosing that much time throwing in a couple of extra changes? I can't see it.
From the infield to the sweeper is a place I have often had to change and lose out to an FXR. In my mind the FXR's at Mt Welly have the advantage of a wide power spread making them very easy to ride, I am looking to emulate that with my stroker.
The veriable inlet has helped clean up the carburation and the stroker will take full throttle cleanly from 3,000 rpm now, but there is not much power untill 8k. I want to lift the torque curve in the 5-7 region and have a 6k power spread like the FXR's.
Now, which would you rather ride, something that has good power for 6,000 rpm or something you have to row around with the gear lever.
F5 Dave
20th May 2011, 17:00
Anecdotaly some may suggest the latter rather than the former. And throw in some copious clutch lever work into the mix. I mean you don't want to get bored out there.
Heck after leaving the pits I wouldn't notice if a bike made power 3000rpm under peak. I'd be more concerned with over rev for ease of racing.
bucketracer
20th May 2011, 17:25
Anecdotaly some may suggest the latter rather than the former. And throw in some copious clutch lever work into the mix. I mean you don't want to get bored out there.
Yes thats right TeeZee, the medium to average rider will lap much faster and have more fun on a bike that they have to play a tune on, with the clutch and gear lever than they ever will with a bike that has a wide solid spread of power.
Anecdotaly to go fast you need a peaky engine...... :innocent: ....... and talent.
Pumba
20th May 2011, 18:34
Yes it is getting a bit wide...........
Almost wide enough to give a kick on the way past:whistle:
Kickaha
20th May 2011, 18:54
just Talent.
I'm well fucked then, I ran out of talent years ago
In my mind the FXR's at Mt Welly have the advantage of a wide power spread making them very easy to ride, I am looking to emulate that with my stroker.
You may also be underestimating how their lack of outright power may also contribute.
A nice friendly power spread without too much kick and a relatively good handling frame and suspenders seems to be the best place to start with a bucket. (on a Kart track)
The bike Hels had that was the opposite (Daves old H100) was the scariest bike I've ever ridden.
Rangi is quite a fast bike but without the good handling part he is quite, um, "exciting".
Having said the sensible bit: Fuck it, MOAR POWER!!!
bucketracer
20th May 2011, 20:03
You may also be underestimating how their lack of outright power may also contribute.
I think TeeZee would agree with you, he has talked about that aspect of the FXR's.
After riding TeeZees bike last Sunday, Kel thought it arrived at the next corner much faster than he expected and that caused him to slow down too much. Whereas his FXR sort of arrived at the right speed.
Gigglebutton
20th May 2011, 21:18
I think TeeZee would agree with you, he has talked about that aspect of the FXR's.
After riding TeeZees bike last Sunday, Kel thought it arrived at the next corner much faster than he expected and that caused him to slow down too much. Whereas his FXR sort of arrived at the right speed.
Kel rides a concrete pump :innocent: he's not used to the power. In time he would tame it and be awesome on it.
bucketracer
20th May 2011, 21:44
Good idea Bert, much better than the electric door lock I was thinking of. The 5V should be easy, I can run the 12V output from the Ignitech through a TO220 5V regulator chip, easy.
I don't know much about RC servos, how are they controlled? power on to turn, then off to stop? reverse polarity to change direction? Or is there different terminals for forward and reverse?
A bit on how RC Servos work........ http://www.horrorseek.com/home/halloween/wolfstone/Motors/svoint_RCServos.html#RCServo (http://www.horrorseek.com/home/halloween/wolfstone/Motors/svoint_RCServos.html#RCServo)
The interesting part is the control signal. An RC servo motor doesn't just run when you give it power. It's an intelligent device, and you must tell it what you want it to do. The servo is controlled by a series of pulses, wherein the length of the pulse indicates the position to take. You need something that drives the servo with that control signal.
And more here........ http://www.repairfaq.org/filipg/RC/F_Servos.html
husaberg
20th May 2011, 22:38
Originally Posted by TZ350
Yes it is getting a bit wide...........[/B]
Think Alpha 1960's with the crankshaft shaped as the disk valve but with the carb in the std location for a reed or piston port?
worth revisting anyone?
239379
I know its an old idea but so is the Toroidal head.
Villiers had Toroidal heads that is in 1962-63 and they stole that from diesel technology only later to be rediscovered 30 odd years later for gp bikes.
so why not look back.
It is truely neat to see the two stroke still getting developed imagine what a two stoke would be like if it had all the technolgy thats been thrown at the 4 stroke in the last 30 odd years ,
Think variable height transfers port as well as 2-3 stage exhaust valves variable inlet heights lengths ex pipe lengths coupled with 4 stroke smart ign ECUs fuel injection etc.imagine how drivable it would be.
Everyone has tried to keep the 2 stroke simple and i think that was the downfall.it stagnated then couldn't cope with the pollution regs.
I had an idea with a std disk valve set up ie disk on the side with carb to have the disk driven via a jack shaft so the disc opertes in reverse to the crankshaft rotation.
With the disk valve in reverse you can use bobweights like an old scool advance retard to retard the disk timming so with higher revs you get more peak power and its still driveable down low.
Plus you get the added advantage of a larger disk valve which improves the flow area at the start and finish of disk valve opening.If you get my idea.
One last unrelated thought is with the 30 od hp air cooled 125 is how long does the power last for on the dyno say dyno reading after 30 secs all out at max revs.how much are you losing with power fade even with the copper fins etc.
A bit on how RC Servos work........ http://www.horrorseek.com/home/halloween/wolfstone/Motors/svoint_RCServos.html#RCServo (http://www.horrorseek.com/home/halloween/wolfstone/Motors/svoint_RCServos.html#RCServo)
The interesting part is the control signal. An RC servo motor doesn't just run when you give it power. It's an intelligent device, and you must tell it what you want it to do. The servo is controlled by a series of pulses, wherein the length of the pulse indicates the position to take. You need something that drives the servo with that control signal.
And more here........ http://www.repairfaq.org/filipg/RC/F_Servos.html
While this is a valid point it is only one form of RC servo; even then it could be resolved with some simple electronic.
but here is another solution for you: (Jaycar)
http://www.jaycar.co.nz/productView.asp?ID=SS0901&keywords=solenoid&form=KEYWORD
pull type solenoid. all you would require is a return and stopper for you armature. you will require more onboard power; but it would be a simple solution to start with; if you only want open/close
I think TeeZee would agree with you, he has talked about that aspect of the FXR's.
After riding TeeZees bike last Sunday, Kel thought it arrived at the next corner much faster than he expected and that caused him to slow down too much. Whereas his FXR sort of arrived at the right speed.
Gee that makes me sound like a right klutz, but generally correct. The FXR with its lack of power just flows around Mt Welly, the focus is on carrying the speed into and through the corner i.e. its going into the corner that you have to make the pass because it doesn’t have any real drive on exit.
The GP with so much extra power really required a different approach, it was like riding the old 250's, corner entry was used for wiping off speed, it was the exit where it all happened! But that wasn’t the aim of the last outing.
All going well TZ will let me have another crack (with a set of Dunlops please), if I use the box and keep it revving then surely it’s going to smash my FXR lap times?
Concrete pump? Mate that’s a bit unkind, perhaps the bike weighing twice as much as me has an advantage?
wobbly
21st May 2011, 10:41
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.
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.
Wobbly; have you played around with the more modern Exhaust servos? say a ZX6r??:innocent:
I'm assuming/hopeing that they run on a similar config/wiring as a Yamaha powervalve servo.
And given heaps of people have been cutting them out (seems to be a common so called improvement) there should be a nice supply of them sitting around the place...
Wobbly/Rob
in-terms of rotary valve; would there be some merit into a design similar to the TZR Exhaust valve (a rotating drum, with cutout) for this intake application; seems like a simple machineing job (two holes intercepting at 90 degrees) and would restrict/disturb the flow less at the higher revs than the butterfly.??
TZ350
21st May 2011, 15:28
Thanks, there have been some very interesting ideas posted on this page.
239402
I have some of these steppers from an old printer but in the hold position they are pretty current hungery as the motor has to draw current to move or hold its position.
239403
The RC Servos geared motor means the servo does not have to be drawing motor current when it is holding its position, but it does have to receve a stream of (goto) position commands, even if its goto the same position its already at (ie hold position).
From what I have read, the RC Servo has a handy feature, when it is not receving a goto signal it returns to its mid point.
239416 http://www.societyofrobots.com/actuators_servos.shtml
This is handy because the midpoint could be used to hold the V Tec valve fully open and when the rpm is below the setpoint (power band) the Ignitech can "turn on" a 555 timer that will send a stream of goto fully closed commands to the RC Servo.
239408
Then when the rpm hits the power band the Ignitech turns of the 555 timer and the RC servo returns to its midpoint, fully opening the V Tec valve.
Simple as.
I would like to use the Ignitec and its power valve servo control feature to "pull" a slippery pipe. I have had a look at the setup page in the Ignitec software but would like to know more about how the Ignitec is interfaced electrically with the power valve servo.
wobbly
21st May 2011, 16:40
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 programed.
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.
husaberg
21st May 2011, 17:35
[TZ350;1130067866]Thanks, there have been some very interesting ideas posted on this page.
If you want to try a RZ sevo motor you can try one i have.brought a couple of years ago for a cr500 project.
The simplest method I could think of to activate the vtech valve would of course to be a spilter box on the the throtle cable much like on an autolube pump .It would be real simple and be modulated with the throtal opening rather than revs.I realise this may be overly simple.
jasonu
21st May 2011, 18:12
just Talent.
Well that leaves Trustrum (F5Dave) out...
jasonu
21st May 2011, 18:16
Gee that makes me sound like a right klutz, but generally correct. The FXR with its lack of power just flows around Mt Welly, the focus is on carrying the speed into and through the corner i.e. its going into the corner that you have to make the pass because it doesn’t have any real drive on exit.
A lot like riding a 50 in F4 or an RS125 in F3.
bucketracer
21st May 2011, 21:41
239424
A better simple 555 RC Servo driver, parts list and construction details http://sarconastic.tripod.com/servodriver.html
bucketracer
21st May 2011, 22:08
The Turnigy 760HV servo tester was custom designed to be the most accurate and accommodating servo tester available. Its quality case design reflects the thought and design of this device. The 760HVs versatility comes from the high-spec potentiometer and its high-end NEC chip which can handle low(3v) and high(12.6v) voltages.
$20 http://www.trademe.co.nz/Toys-models/Radio-control/Parts-accessories/Servos/auction-376901657.htm
239425
Could be easy to convert to the RC Servo driver required for the V Tech Servo, easier than making your own driver from scratch anyway.
gamma500
22nd May 2011, 08:42
That old Honda pipe mod drawing is completely useless, it was never used by the factory in any form.The rear cone is insanely steep.
And the so called A Kit pipes were designed to work with high Ex ports - where the customer engines all had 83*ATDC to let them rev without an electric powerjet.
I have much better designs with a ton of dyno time on them, but of course they are all specific to 50Hp 125 cylinders, not 30Hp 100cc designs.
Here is one that has won dozens of 125 kart titles, but again it should just point you in the right direction for the 100.
What effects does expanding belly have in that kart pipe?
The Turnigy 760HV servo tester was custom designed to be the most accurate and accommodating servo tester available. Its quality case design reflects the thought and design of this device. The 760HVs versatility comes from the high-spec potentiometer and its high-end NEC chip which can handle low(3v) and high(12.6v) voltages.
$20 http://www.trademe.co.nz/Toys-models/Radio-control/Parts-accessories/Servos/auction-376901657.htm
239425
Could be easy to convert to the RC Servo driver required for the V Tech Servo, easier than making your own driver from scratch anyway.
Now your talking...
Not such a stupid idea.
speedpro
22nd May 2011, 12:48
What effects does expanding belly have in that kart pipe?
The expanding belly is a common problem with older bucket racers. No natter how good the pipe if there is an expanding belly the bucket will go slower. Talking to Gaz last night and the problem of expanding belly came up. Gaz has an expanding belly but I think it's the hole in his leg that'll be slowing him down at the moment.
wobbly
22nd May 2011, 13:38
Expanding bellys have various effects as noted above.
But in pipe design it allows you to increase the effect of the reverse cone, without making it shorter.It also increases the volume and can reduce the propensity of the wave to create a shock front ( killing energy) as it reverses back toward the diffuser.
This is seen as a quite noticeable blip in the sim, example below seen at around 20* before TPC, of the pressure ratio at the EX port
bucketracer
22nd May 2011, 17:54
Dad was relating a story, told to him by Speedpro about how he tried a RamTube on his Suzuki 50. Apparently it worked really well at idle, which was the RamTubes resonant frequency and again at the higher harmonics as the engine was reved up, but it killed the engine in between resonant peaks.
The peaks were remarkable but the down sides out weighed the benefit of the peaks and there didn't seem any real way of using the idea. A variable length inlet might work but it would be hard to have it long enough for the bottom and then make it short enough for the top end.
Here is another idea about how to change the resonant length of the RamTube, from http://www.phys.unsw.edu.au/jw/woodwind.html#sound
239451
Vary the length of the reflected wave by opening holes in the side of the RamTube like they do with Wood Wind Instruments.
239452
By having holes at odd distances along the tube, the harmonic frequencies in the RamTub could be kept in step with the engines RPM.
The holes could be opened and closed by RC Servos.
True it would make TeeZees bike six feet wide but as long as he sticks to the outside of the track all should be good, or maybe he could put an outrigger wheel on the RamTube and enter it as a side car. Seriously the idea has got to be worth looking at.
Norton Rotary GP bike with variable length inlet http://www.youtube.com/watch?v=48foOHK2tyA
And a bit of a speed comparison http://www.youtube.com/watch?v=kBg86bjr8l0&feature=related
(http://www.phys.unsw.edu.au/jw/woodwind.html#sound)
speedpro
22nd May 2011, 18:30
Or you could look at an R1 intake system
Moooools
22nd May 2011, 18:34
Dad was relating a story, told to him by Speedpro about how he tried a RamTube on his Suzuki 50. Apparently it worked really well at idle, its resonant frequency and again at the harmonics as the engine was reved up, but it killed the engine in between resonant peaks.
The peaks were remarkable but the down sides out weighed the benefit of the peaks and there didn't seem any real way of using the idea. A variable length inlet might work but it would be hard to have it long enough for the bottom and then make it short enough for the top end.
Here is another idea from http://www.phys.unsw.edu.au/jw/woodwind.html#sound
239451
Vary the length of the reflected wave by opening holes in the side of the RamTube like they do with Wood Wind Instruments.
239452
By having holes at odd distances along the tube, the harmonic frequencies in the RamTub could be kept in step with the engines RPM.
The holes could be opened and closed by RC Servos.
(http://www.phys.unsw.edu.au/jw/woodwind.html#sound)
It sounds good when you express it like that, but in reality opening holes does not work for an engine.
Opening holes works for STANDING WAVES. Standing waves are standing because they have no velocity.
The air coming into a carburetor does need velocity (or else it wouldn't work). So the standing wave model does not apply.
__________________________________
However it can be more closely modeled with other principles of SHM (Simple Harmonic Motion).
A spring oscillates a mass (m) at a frequency proportional to 1/m. In other words: the larger the mass the lower the frequency.
In this case the mass is the air inside the inlet tube to the airbox, and the spring is the compressing and expanding air inside the airbox.
Therefore if the inlet tube is made smaller (width or length) it will oscillate at a higher frequency for the top end, and if the inlet tube is made smaller it will oscillate slower for the bottom end.
You do not, however, need a tube that is shortest at idle and longest at the top end. You would still have the resonant peaks that occur when the engine is at 1/2,1,2,3,4 or 5 times the resonant frequency.
So all you would need is to have a pipe set up for say 4000RPM at full length and this would cover 1000rpm, 2000rpm, 4000rpm, 8000rpm and 12000rpm at full length.
In between these points it could be shortened with a servo to the correct length and be put back out to full length as it reaches the next point.
This would give you maximum benefit at 4000RPM as it would be one oscillation per revolution, whereas 8000rpm would be one oscillation every second revolution and at 8000 rpm it would only be in step every third revolution.
__________________________
Anyway, that is my spiel over. I just love physics like that.
If I have made any mistakes in there let me know, and I will beat myself up.:shutup:
Enjoy
bucketracer
22nd May 2011, 19:00
This would give you maximum benefit at 4000RPM as it would be one oscillation per revolution, whereas 8000rpm would be one oscillation every second revolution and at 8000 rpm it would only be in step every third revolution
Ok Mooooools, sounds good, now if the pipe is say 1m and correct at 4,000rpm what would the lengths need to be for 5, 6 and 7,0000?
Would that be, if 4K=1m then 5k=0.8m 6k=0,67m 7k=0.57m and then back to 8k=1m again, 8k is a half fundamental and 9k=0.8m 10k=0,67m 11k=0.57m all for halves and then back to 12k=1m and 13k=0.8 for third waves.
Not to sure about my numbers but if they are right I can see how your idea would work.
The fundamentals will have the most effect and the halves less so but the coming on the pipe more than makes up for it. If I have understood all this correctly it looks like it could be made to work and is worth a try.
239458
Looking at TeeZees graph, I think that fundamentals need to be around the 4-5-6-7 mark.
Next time TeeZee has his bike on the dyno, Thomas and I will play with some tubes to see if we can find some sort of resonating length to start with.
Moooools
22nd May 2011, 19:25
It is too hard to do the maths on it. But I just found this good link with all of the theory. It pretty much backs up my on-the-fly model of the physics ivolved.
http://motorcycleinfo.calsci.com/Airboxes.html
And also just realised that you would not even have to have the steps in the inlet.
If can you make the airbox small enough (not too small though) it will increase the spring constant of the air inside. This means a shorter length pipe can be used and which would result in a shorter range of motion need for the variable length pipe.
If you cannot get the airbox small enough then the inlet pipe can be made wider so that the is more change in volume for a given change in length. I can't be arsed doing the calculations but they are all at the link above.
Looking at TeeZees graph, I think that fundamental need to be around the 6-7 mark.
Next time TeeZee has his bike on the dyno, Thomas and I will play with some tubes to see if we can find some sort of resonating length to start with.
I do wander if improvement could be resolved with good low-mid range jetting (more likely needle shape and slide cutout) and ignition; given the performance above this range.
Maybe an exhaust powervalve could be in order??? I'm sure you guys are talented enough to machine / install a blade type valve into the GP to adjust the port heights for more bottom end.
Moooools; I think there was a Java app floating around a few years back that parelled the info on that webpage. I have a funny feeling the boys covered that back around page 80?? around the time the euro boys poped in.
Also I stumbled across this website (Pistons).
http://www.strikeproducts.com.au/pistons.asp
Kartng pistons and one offs... Quoting another forum on the background:
The guy in Perth that does the Strike pistons is Ken Seber. He used to work for Orbital engines and set up the gravity casting facility there. When he was made redundant he took on the piston casting setup and started making kart pistons. Realy did make a nice part....
bucketracer
22nd May 2011, 19:43
Thanks Bert and Mooools this is all good stuff, next time the bike is up on the dyno we will try a few bits of pipe and see what happens.
bucketracer
22nd May 2011, 22:36
But I just found this good link with all of the theory. It pretty much backs up my on-the-fly model of the physics involved. http://motorcycleinfo.calsci.com/Airboxes.html (http://motorcycleinfo.calsci.com/Airboxes.html)
Had a look at the link and maths.
They suggest about 300mm for 10,000rpm in a 4-Stroke (depending on diameter) so that's 5,000rpm for a 2-Stroke, now we have something to start with.
wobbly
23rd May 2011, 09:46
There is no "formula" that can directly generate a tuned length for the intake of a 2T as there are too many extra variables involved.
Helmholtz doesnt apply and neither does organ pipe theory as the tuned tube is connected to a varying volume, with a varying intake end area
In a rotary valve there is another scenario going on and that is the standoff issue.
The actual "real" reflection point of an intake tube is about 1/2D past its end point, this is reduced alot by having a tapered and or a bellmouth entry, but the waves bouncing up and down the tract - still hits "soft" atmosphere out past the carbs end.
That is why there is a "fog" of fuel sitting outside the carb when the effect is working.
Thus in practical terms we find that with a RV, its all but impossible to get the intake short enough to have the second harmonic ( the most useful of the tuned lengths) in tune with the engine "forcing frequency" when in the powerband, along with reducing the deleterious effects on carburation caused by too much stand off.
Aprilias have a 42mm carb hanging off the RV cover with as short a body as they can, with no "manifold" at all really.
In a reed valve setup,tuned for peak power around 12000 rpm, we find that the best tuned length is around 135mm from the reed tip, to the end of the bellmouth works best.
What this does is hard to explain but easy to show you.
The wave bouncing up and down the intake length, when its "in tune", will arrive at the reeds as a + going pressure ratio, at the same time as the case drops below atmospheric, due to the piston rising - plus the pipe diffuser sucking like hell on the Ex Port around BDC.
When this happens the reeds have + on one side and - on the other.They open real fast, with little "flow energy" being waisted, and Hp is made big time for free.
Here is a graph of a very winning 125 kart engine, the only change being to use a 20mm shorter intake rubber that hit the 135mm rule, spot on.
The sim curve shows the intake pressure ratio crossing zero at the same time as the case, but with opposite signs,right at the point in this case when the PV closes and the engine is coming on the pipe as well.
Using the second harmonic spreads this effect over the widest band with the highest useable effect.
Interesting stuff but left me slightly confused, didnt the piston port motors rely on calculated tuned intake lengths? I understand helmholtz dosent apply to reed motors as the reeds effectively block the reverse flow, but surely the rotary disk, even though they are usually forced to have very short intake lengths can utilise helmholtz and tuned length. From memory Kawasaki ran a system called ram tubes on some of their rotary valve racers. Is it not possible we were seeing the benefit of helmholtz when TZ increased the GP’s crankcase volume? i.e. a bigger crankcase volume lowers the Helmholtz-frequency (as does a longer intake length). The introduction of the bellmouth may have helped as well I guess.
I am curious as to the Aprilia RSA’s intake runner; there must be one as they run a pressurised airbox?
ps. Love the simulator shot
wobbly
23rd May 2011, 19:29
Well you see its something lots of closet professors delight in doing - trying to assign hard numbers to a highly variable system, but as in many cases like this they get shagged up the bum by reality.
Increasing case volume decreases the Helmholtz resonance frequency, but big volumes work better at high rpm, due to the pipe having greater volume to suck on.
Works in reverse, oh dear.
The rotary valve engines are more affected by the intake resonance creating big standoff effects, thus the intake length is best when as short as possible, as this reduces the resonance "tuning" to a point above the engines forcing frequency.
Forget intake length tuning - it doesnt work. edit ( in a racing engine with closing at 80* or more ), and even worse is that the standoff issue cant be included in a sim,to show the bad effect on fueling, overcoming any advantage gained via "ram tuning" length.
Intake airbox theory is quite different.It is basically a simple Helholtz, but again, in practical terms it is all but physically impossible to create a big enough volume that is "correct".
The intake diameter and length are critical, and do conform to theoretical analysis.
Reed intake length tuning does work well in a sim, where the length and case pressure effects can be accurately predicted,but as to creating a simple theoretical relationship to give a correct tuned length for any engine config, i just cant see it ( love to be proved wrong, get Dr Aitken on the job).
wobbly
25th May 2011, 09:20
Just to add a little more to the intake tuning scenario,the TD and TZ piston port engines had an "insulator" spacer on the cylinder about 25mm wide.
We all thought this did what it was called ie kept heat off the carb,but no.
Shorten that spacer by 5mm and it was absolutely impossible to jet the carb.
Even blipping the throttle you saw huge standoff at the bellmouth.
Make it longer to pick up bottom end power, and for every 1 Hp gained at 8000 you lost 2 at 10000.
So again, reality fucks over theoretical analysis.
The shorter length was technically correct for the rpm,but was impossible to utilize.
Edit, the other thing I forgot to add before re Mr Helmholtz.
Its all very well making an assumption that the intake and the case vol is in fact a Helmholtz - the problem is there are 3 others doing his finest.
The case connected to the transfer ducts, the transfer ducts connected to the cylinder volume, the cylinder volume connected to the exhaust duct, and the exhaust duct connected to the pipe volume, and the pipe volume connected to the stinger.
How many did I say, anyway we have a multiplicity of ducts and volumes, trying to define one as independant of the rest is suspect to say the least.
TZ350
29th May 2011, 11:12
239753
Interesting, in the hand activated trial of the V Tec there is the beginings of some extra power at the top. Not sure what contributed this, the vetec added an extra 25mm to the inlet tract for 195mm total or possibly the little kick I gave the end of the divider better directs the flow behind the conrod as the incoming air/fuel enters the crank case.
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This is the RC Servo that I am going to use to close the V Tec below 7,000 rpm. There is a small battery pack and a servo tester set to the closed position. The plan is that below 7k the Ignitech activates the relay and allows the pulses from the servo tester to tell the servo to close. Above 7k the relay is open and there are no pulses going to the servo motor so it automatically returns to the neutral position and opens the V Tec.
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Rotary Valve side shows the divider coming right up to the valve. In this view the valve rotates ant-clockwise. The inlet is 45 deg wide and the V Tec closes it 10 deg earlier, I would have liked 30 but this is how the first cut turned out.
Everything is securely glued in place so now we can try a different rotary valve and get into some serious tuning for more power spread and explore water injection.
Next time I make one of these I will try and reposition the divider so it closes earlier, then I can have a realy radical closing point for extra top end power while keeping the wide power spread.
bucketracer
29th May 2011, 20:17
Rotary Valve side shows the divider coming right up to the valve. The inlet is 45 deg wide and the V Tec closes it 10 deg earlier. Then I can have a realy radical closing point for extra top end power while keeping the wide power spread.
In the old Rotax tandem twin, going from 85* ( stock) to 88* is like night and day in overev performance, but carburation becomes finicky and alot of bottom end power is lost.
Hmmm now that TeeZee has found that the V Tec cleans up the bottom end carburetion I think I can see where he could be headed with this variable inlet closing idea...........
F5 Dave
30th May 2011, 09:45
239753
. . .. The plan is that below 7k the Ignitech activates the relay and allows the pulses from the servo tester to tell the servo to close. .
WHY??!!? What kind of drugs are you on? So you might get a boost when the engine is making say 7hp? RG50s will be whipping past you. Or you could just keep it above 9 & enjoy a splendid power range. 8 if you must.
If you could get it to work quickly enough 11.7 would be good. Seems odd that it makes that good power closed. Did you do those runs back to back?
TZ350
30th May 2011, 16:21
Seems odd that it makes that good power closed. Did you do those runs back to back?
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Closed to 7 then open all the way, Thomas had the job of pulling the valve open at the right time.
The runs were not back to back as it took a few nights after work to fit the original V Tec valve, but there were no other changes except it idled better with a smaller pilot jet.
I can't explain the hint of extra power at the top, I hope its still there and can be developed further when we get the thing back together.
F5 Dave
30th May 2011, 17:08
a hint? 1/2 a hp for 1500rpm is more than a hint. it kind of indicates something like timing, or perhaps jetting or temp is different.
But again, why do you care what sort of power you are making at 7000 seeing as its so little? Pit exits for warm up lap?
TZ350
30th May 2011, 18:36
a hint? 1/2 a hp for 1500rpm is more than a hint. it kind of indicates something like timing, or perhaps jetting or temp is different.
If its a real improvement and still there on the next dyno run. My best guess is the kicker at the end of the divider is better at directing the air flow in behind the conrod as the rod sweeps across in front of the inlet port during the induction cycle and this re-directed air flow better balances the incoming air/fuel mixture between the left and right side transfer ducts.
why do you care what sort of power you are making at 7000 seeing as its so little? Pit exits for warm up lap?
When I started the V Tec project I was hoping for FXR like power at 6-7k but all I got was vastly improved carburation from 3k to the 7-8-9k region, a lot of work and not what I was aiming for, but still worth having.
Now I see the big advantage of the smoother low end power delivery as, that it will now be possible to get on the gas much earlier, something the FXR's do well and it should realy hall arse out of the corner, something the FXR's don't do so well.
I guess now with the better carburation, I will also be able to explore later valve closing, like 88 deg ATDC for greater over rev.
But again, why do you care........
A good clean pickup on the carb for a fast start is everything with Buckets, especialy when running a Stroker at Mt Welly.
Buckets4Me
30th May 2011, 18:58
But again, why do you care what sort of power you are making at 7000 seeing as its so little? Pit exits for warm up lap?
maby so he isn't left on the start line (like someone at Taupo a few years ago)
:facepalm: even I managed to pull half a lap on you before you got going :shit:
F5 Dave
31st May 2011, 20:44
So. . .do you launch at 7000rpm? no you don't do you?
Yeah that sucked at Taupo. The pwk carb tended to flood more than my old Mikuni. However after screwing around for ages it turned out the real problem was the clutch inner basket grooves were so prominent they wouldn't allow a race start without dragging on & off. This loaded up tegh 1/2 piston port engine worse than it would a reed one.
Heck after a decade of abuse of the worst abused clutch in bucketdom, - something had to give.:blink:
Had it fixed for when Av rode it though.
TZ350
1st June 2011, 19:52
So. . .do you launch at 7000rpm? no you don't do you?
Too true, but I also don't sit on the line at launch rpm waiting for every one to sort themselves out.
A loaded up engine doesn’t launch well at any rpm until its cleared its throat, it may only take a moment, but that’s a moment too long for any sort of a fast start.
Making a fast start is all about paying attention to detail and going to some trouble with engine setup.
And I am used to making very fast starts, Ill show you how its done next time your up this way.
Too true, but I also don't sit on the line at launch rpm waiting for every one to sort themselves out.
A loaded up engine doesn’t launch well at any rpm until its cleared its throat, it may only take a moment, but that’s a moment too long for any sort of a fast start.
Making a fast start is all about paying attention to detail and going to some trouble with engine setup.
And I am used to making very fast starts, Ill show you how its done next time your up this way.
its true that for the top bunch if guys in any class, the race is quite often won on the start line, but in this situation, it hardly seems like an issue.
F5 Dave
2nd June 2011, 09:23
Oh look Neil has shown up. They finally let you out of rehabilitation?
Yeah I'd agree that a good start is important. But usually there is a clue like some kindly gentleman holding up a flag a few seconds before. Then in typical Auckland fashion someone launches & the flag drops.
But usually there is a clue like some kindly gentleman holding up a flag a few seconds before. Then in typical Auckland fashion someone launches & the flag drops.
Ah you know how it works up here then - we can't wait for the flag to drop, if we did that half the front row would already be at the first corner!
jasonu
2nd June 2011, 11:57
Then in typical Auckland fashion someone launches & the flag drops.
That was Mark, wasn't it???
F5 Dave
2nd June 2011, 16:04
Ah its just as often one of the Dips. You'd think I'd learn after all this time, when in Rome.
In Woodville MX races Gosimer was telling me (he used to go up as the starter when he was big in the Manuwatu Onion club) if you jump the start a couple of times they start you off facing the wrong direction.
bucketracer
2nd June 2011, 18:18
Ive read about this motor configuration before http://vincentcrabtree.co.uk/XR200.aspx Would have been a weapon pre FXR (as far as four strokes go).
Because Team ESE also enjoy 4-Stroke technology and have a few XL/SL100 and 125 engines in a big box somewhere, we flogged this link and posted it here for future reference, thanks Kel.
husaberg
2nd June 2011, 18:36
[QUOTE=Bert;1130067748]Wobbly; have you played around with the more modern Exhaust servos? say a ZX6r??:innocent:
I'm assuming/hopeing that they run on a similar config/wiring as a Yamaha powervalve servo.
And given heaps of people have been cutting them out (seems to be a common so called improvement) there should be a nice supply of them sitting around the place...
This would work I think?
wobbly
2nd June 2011, 20:29
Yea well the windscreen motor off a split screen Morris Minor could be made to work as well.
That version has the poxy single bearing setup, same as ZXR, but is even worse in that it only drives a single cable off the pulley,thus needing spring return.
The newer R1 version of the RZ servo has really good bearing supports in the case for the shaft and has push/pull - just buy one.
Because Team ESE also enjoy 4-Stroke technology and have a few XL/SL100 and 125 engines in a big box somewhere, we flogged this link and posted it here for future reference, thanks Kel.
Kel's post uncovered some interesting reading:
http://www.powroll.com/Tech_crfproject.htm
Not quite what I'd do with a 80 but cool engineering anyway..
Yea well the windscreen motor off a split screen Morris Minor could be made to work as well.
That version has the poxy single bearing setup, same as ZXR, but is even worse in that it only drives a single cable off the pulley,thus needing spring return.
The newer R1 version of the RZ servo has really good bearing supports in the case for the shaft and has push/pull - just buy one.
Eyes out for a R1 then until i find one at the right price the ZX6 unit that I've had for a while; will have to do...
husaberg
2nd June 2011, 22:53
Yea well the windscreen motor off a split screen Morris Minor could be made to work as well.That version has the poxy single bearing setup, same as ZXR, but is even worse in that it only drives a single cable off the pulley,thus needing spring return.
The newer R1 version of the RZ servo has really good bearing supports in the case for the shaft and has push/pull - just buy one.
Personally I think the Morris Minor windscreen motor may be out I think it could be 6 volt positive earth after all.
Seriously now
I did offer tz350 a rz servo to try for free I even suggested a splitter cable of the throttle cable ala auto lube pump on Yamaha.
As I thought the servo seemed to be overkill on a bike where it would be nearly always low throttle opening =low revs wide throttle opening= high revs.with very little of anything else
Wobbly what did you think of my regurgitation of the alpha rotary drive to slim the motor up?
wobbly
3rd June 2011, 08:43
Sorry I missed the "alpha" drive,point me at it to look.
speedpro
3rd June 2011, 16:13
The "alpha" drive wasn't such a success on the Enterprise, which is why they stuck to the standard Warp engines.
husaberg
3rd June 2011, 17:11
http://www.lortim.demon.co.uk/alpha/index.htm[/URL]
Sorry I missed the "alpha" drive,point me at it to look.
This is it a narrow disk valve set up, don't know why I typed the word (drive) for though?
One engine used the half circle crank as the disk valve so the engine looked piston port but was disk valve.
There is pics of about three versions of the engine here below.
Alpha also used to do a knife edged kind of eliptical cross section streamlined shaped conrod that also looks like it would show promise as an idea in a modern engine.
It may have been hollow section when i next get to where the parts are I will post a pic of the conrod.
The conrod was wider to up primary comp also as well as presenting a streamlined cross section to the direction of the incoming charge.
The first pic shows an example of one.
Alpha is a company that used to make full circle cranks for Villiers Greeves etc and big ends for all sorts of bikes.
I know these are old ideas but back in the 50s-60s alot of ideas where tried but the metalogy of the time was lacking behind the ideas example Villiers had Toroidal heads in 1962-63 on the starmaker engine and they stole that from diesel technology only later to be rediscovered 30 odd years later for gp bikes.
so why not look back.
wobbly
4th June 2011, 10:31
The idea seems ok untill you start drawing the thing.
I did a very quick sketch and you can see that very little flow will occur until the opening "edge" of the crank is well past the port.
It does have symetry of flow in its favour, that is why the rear mounted inlet on a RSA is alot superior, but I dont see that this setup would work better than an ordinary side mounted disc valve.
husaberg
4th June 2011, 11:11
The idea seems ok untill you start drawing the thing.
I did a very quick sketch and you can see that very little flow will occur until the opening "edge" of the crank is well past the port.
It does have symetry of flow in its favour, that is why the rear mounted inlet on a RSA is alot superior, but I dont see that this setup would work better than an ordinary side mounted disc valve.
I think (and I could be well wrong to)
That the direction of the flow is more towards being at right angles to the crank to get around this, That’s what it seems to me in the other pics.of the various models of engines.
The idea I thought was to get the advantage asymmetrical inlet timing and not have the charge have to get around the edges of the crank like a conventional disk valve.
I also think this approach to disk valve design layout maybe might allow for a bit more cylinder wall for transfers?
My thinking also was tz350s bike is getting wide now with all the gear hanging off the side.
Now a different idea for your input.
Some one brought up a advance retard idea earlier but to get it to work the weights would have to be build out of antimatter (maybe speedpro has some left over from his star trek jibe)
The other idea I had was posted back a couple of pages ago with a retarding conventional disk valve for more top end without the losses down low.
If you had a contra rotating Disk valve with a jackshaft to reverse the direction with a bob weighted in this case retard (much like a bob weight centrifugal distributor advance on a 50s Morris minor or 70s ford escort)
I suppose only in reverse hence the jack shaft.
Ie the faster it goes the more retard.
(The more retarded the disk valve timing the more top end according to graham bell anyway)
This idea also would give the advantage at small degrees of disk openings of a larger flow area from the larger disk because it is offset from the gear off the crankshaft without the increase in crankcase/crankshaft size.
If you took this design a step further you could spin the whole engine in reverse like the later tz250s (pre v twin)
With this you can run a wider exhaust port because the piston thrust would be acting on the inlet (which has more cylinder wall for support rather) than the exhaust port.
And run the disk in conventional rotation direction for retard .I don't know if I am explaining it well I might have to draw a picture
I know these are old ideas but back in the 50s-60s alot of ideas where tried but the metalogy of the time was lacking behind the ideas example Villiers had Toroidal heads in 1962-63 on the starmaker engine and they stole that from diesel technology only later to be rediscovered 30 odd years later for gp bikes.
so why not look back.
Great to see these early designs. With the current RSA's rear disk design the flow is unobstructed by the crankwebs plus the disk would offer less friction and better sealing.
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239991
TZ mentioned how the Honda RS pipe inlet is larger than the GP exhaust port outlet, while this is common place on 4 strokes for the purpose of AR I wasnt aware it was used on 2 strokes but on reviewing RSA photos I came across this
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Jan Thiel "One wants the pressure wave coming back into the cilinder but NOT the burned gases that are hot and can cause detonation!"
Makes sense.
And -
TZ I think Jan could be pleased with your efforts/experiments with varible inlet timing, when asked what he would have liked to develop further on the RSA he replied "there were many ideas about a variable tailpipe! and also about variable inlet timing". You never know mate, direct the questions to the right people in the european forums and you may just get an answer from the master himself
OK last post then I'll go and work on my motor
Classic designs from the past, what about a twin rotary disk single, Yamahas 125cc RA41 from 1961
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pictures courtesy of http://www.deraceheldenvanweleer.nl/index.php/topic,127.msg12169.html#msg12169
Yow Ling
4th June 2011, 15:41
If you took this design a step further you could spin the whole engine in reverse like the later tz250s (pre v twin)
With this you can run a wider exhaust port because the piston thrust would be acting on the inlet (which has more cylinder wall for support rather) than the exhaust port.
And run the disk in conventional rotation direction for retard .I don't know if I am explaining it well I might have to draw a picture
which TZ's are you referring to, the first reverse rotating tz was the tz250h, my understanding is that this was to remove the piston thrust from the inlet which was a piston port and move the piston thrust to the exhaust side. the reverse cylinder tz250 W ? was a case reed so didnt have the piston trying to jump out the inlet problem. running the engine through a jackshaft costs hp so you need a good reason to do it
husaberg
4th June 2011, 23:12
Yow Ling;1130079065]which TZ's are you referring to, the first reverse rotating tz was the tz250h, my understanding is that this was to remove the piston thrust from the inlet which was a piston port and move the piston thrust to the exhaust side. the reverse cylinder tz250 W ? was a case reed so didnt have the piston trying to jump out the inlet problem. running the engine through a jackshaft costs hp so you need a good reason to do it.
I think the jackshaft cost them a hp but they got a bike that would last races.
I am open to correction but my understanding was it ran in reverse because the exhaust port was so wide on the (I think G models) they were becoming extreme piston eaters.
Yamaha didn't want to lower the output by narrowing the ex port so they ran the engine backwards so the piston rode on the more supported inlet cylinder wall. I’ve got the full story in a Yamaha history book somewhere. I post the article when I come across it.
I think it coincided with the pv so my guess is the tz250h model. Defiantly not the reverse cylinder and was piston port.
with the contrarotating disk I think the top end gain without midrange loss and the gain from the larger disk would more than compinsate.
Although the rsa engine sure looks sweet I guess Jan is the same dude who was the lead designer at aprilia through the 90s when Mad Max was king (whithimner .. sp?)
bucketracer
4th June 2011, 23:24
TeeZee Interesting Idea
From http://www.rgv250.co.uk/forums/index.php?/topic/16334-building-f250/page__st__740
Just booked up a dyno session towards the end of may to check the bikes running ok so the first race on it should be in june, also to try out the new top fairing air scoop and new airtube and i have also made a couple of new shaped bellmouths to try out as well, when i made some before i made a long one and a short one the long one gained two bhp at the top end but lost some midrange the short one gained 1bhp at the top end but re-gained the midrange back, so i have tried to make a bellmouth with the bhp of the long one and midrange of the short one a mixture of the two one of them i have made an alloy plate to fit to it so that i can try it without the plate fitted then fit the plate and try it again,i want to see what difference the plate will make will it work like one bellmouth when opening the throttle giving the midrange of the short one then when fully open give the top end of the long one one can only suck it and see.
barry
bucketracer
4th June 2011, 23:31
I am open to correction but my understanding was it ran in reverse because the exhaust port was so wide on the (I think G models) they were becoming extreme piston eaters.
Yamaha didn't want to lower the output by narrowing the ex port so they ran the engine backwards so the piston rode on the more supported inlet cylinder wall. I’ve got the full story in a Yamaha history book somewhere. I post the article when I come across it.
I asked Dad (TeeZee) and he said he remembers the "G"s as piston eaters, the skirt edge on the inlet side would get hammered in by the bottom edge of the extra wide inlet port. As the piston thrust side is on the same side as the inlet and the thrust tipped the piston skirt into the inlet port, pistons would have to be replaced every meeting or so.
TZ350
5th June 2011, 08:34
http://www.lortim.demon.co.uk/alpha/index.htm[/URL]
This is it a narrow disk valve set up, One engine used the half circle crank as the disk valve so the engine looked piston port but was disk valve. There is pics of about three versions of the engine here.
I think the crank web inlet idea would be a good way to get the carb out of the way but the crank webs on the GP are to narrow to be able to get enough port area.
If you had a contra rotating Disk valve with a jackshaft to reverse the direction with a bob weighted in this case retard (much like a bob weight centrifugal distributor advance on a 50s Morris minor or 70s ford escort)
I suppose only in reverse hence the jack shaft.
Ie the faster it goes the more retard.
That is an interesting idea, it would take a bit of work, and more time than I have, it would be interesting to see though.
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My own approch also decreases the size of the inlet tract when the inlet closing point is reduced, this keeps the inlet tract gas velocity up.
I tried the RC Servo out and it opens/closes the valve OK and quickly enough but the RC servo does not automaticaly return to its neutral position like I thought it would.
So now I have to find a way of driving the servo both open and closed using a single switched output from the Ignitec. Probably use a Com-NO-NC relay and two RC Servo testers, one set to open the other set to the closed point.
With the RC Servo signal line connected to the Com of the relay and one servo tester connected to the NO and the other to the NC then whenever the Ignitec makes the relay change state the Servo receves a different signal and opens/closes.
husaberg
5th June 2011, 09:14
So now I have to find a way of driving the servo both open and closed using a single switched output from the Ignitec. Probably use a Com-NO-NC relay and two RC Servo testers, one set to open the other set to the closed point.
It was a joke but got me thinking don't windsceen motors have a memory functon of returning to initiation point I know it used to be an overcentre switch on the ancient one's but surely modern ones are a bit more trick.
At worst I think they could be the sourse of your relay.
Failing that have a look at the Jaycar site heaps of automotive curcuits and kits plus ideas.
Aditionally like I said earlier i have a rz one available for loan/lend.
but why can't use use a simple cable off the throttle and use a correct shaped ramp cam to get the right tipping point .
wobbly
5th June 2011, 10:14
Why all the shagging about with relays and RC crap - just stick a PV servo on the Ignitech that drives it open and closed, with loop feedback accuracy and simplicity.
The problem with connecting to the throttle is that in the situation where you want maximum effect, wide throttle/low rpm, it works the worst.
The best setup would be a 3D map for the servo in the Ignitech with PV position over rpm and TPS ( this is coming soon as I have been hassling them for over 12 months about it) but simply relating servo to rpm is way better than just a valve opening as you open the throttle.
TZ350
5th June 2011, 10:49
Why all the shagging about with relays and RC crap - just stick a PV servo on the Ignitech that drives it open and closed, with loop feedback accuracy and simplicity.
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
husaberg
5th June 2011, 13:27
The problem with connecting to the throttle is that in the situation where you want maximum effect, wide throttle/low rpm, it works the worst..
I know I should be getting this but in a race bike as oposed to a roll on roll off situation and passing and acelerating moderatly etc you have in road situations .
The only times I can think off where you would have a wide throttle low rpm would be when...?comming out of a harpin is the only thing that springs to mind?
What am i missing I can follow the high rpm/low throttle sernaro for over run into corners chicanes etc .
I know from dataloging far better riders than myself S.F.A time is spent anywhere near full throttle even on open curcuits.
but where is the wide thottle opening low revs situations?
but where is the wide thottle opening low revs situations?
On an FXR (yes I know it's a diesel) out of just about every corner.
husaberg
5th June 2011, 14:00
On an FXR (yes I know it's a diesel) out of just about every corner.
Try the left side lever down by your foot, click down once instantly high revs low throttle opening although may result in crankcase venting on the diesel pig FXR
Correct gearing for MT Welly on a diesel pig gets you 2 gear changes per lap.
I've tried doing the Randy Mamola quickstep but it increased my lap times, on an FXR less is more when it comes to dancing on the shifter.
TZ350
5th June 2011, 15:54
Correct gearing for MT Welly on a diesel pig gets you 2 gear changes per lap.
Less is better, we are aiming for only 2 changes per lap too, rowing the bike around with the gear leaver only slows you down I recon.
ajturbo
5th June 2011, 16:19
Ok... as you all know i know HEAPS about nothing...:facepalm:
BUT i have just got the RG 50 going again..
I found out that if you clean all the jets, it can drink and breath fire.... :woohoo:
So when is the next race, i will need to "test " it... as i do not want any of the locals knowing what i have in the shed...
Next the GT 125 twin will get the same treatment...:yes:
240032
husaberg
5th June 2011, 16:36
Less is better, we are aiming for only 2 changes per lap too, rowing the bike around with the gear leaver only slows you down I recon.
Push lever up to go faster! Just kidding.
If you want to get away with less gear changes .
What about centrifical clutch ala ktm50 sx.
= no gear changes per lap always on the pipe.
Before I am flamed Its not like a Honda 50 clutch though more adjustable chainsaw.
TZ350
5th June 2011, 17:00
If you want to get away with less gear changes .
What about centrifical clutch ala ktm50 sx.= no gear changes per lap always on the pipe.
Could be good.
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But the KTM looks like a slipper clutch with a single gear???? Am I looking at the right one?
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I have seen dyno graphs of engines with variable drive, more or less on the power at whatever speed. The longest flattest rear wheel power spread I have ever seen. Might be worth looking at.
Last time out at Mt Welly Kel was able to do a few fast laps with the GP using only 2 gears, we are pretty close to getting a wide enough power spread for single gear laps.
So it would be a quick start, up through the gears to 4th and then drive on the throttle the rest of the way. With the overall gearing set so the engine is at its best on the two or three short straight’s that matter.
That’s the plan.
Ok... as you all know i know HEAPS about nothing...:facepalm:
BUT i have just got the RG 50 going again..
I found out that if you clean all the jets, it can drink and breath fire.... :woohoo:
So when is the next race, i will need to "test " it... as i do not want any of the locals knowing what i have in the shed...
Next the GT 125 twin will get the same treatment...:yes:
You have two weeks to get the GT going. 19th June at Kaitoke.
husaberg
5th June 2011, 18:23
But the KTM looks like a slipper clutch with a single gear???? Am I looking at the right one?
If you are a KTM dad (the Clutch) is the bane of your life if you have a 08 or earlier model,
But man does it keep them on the pipe and puts the power down like you would not believe.
Yes the are one gear but they go 0km to 55mph like you would not believe and are adjustable for kick in speed and characteristics.with special cuped washers and flat washers.
Go to a MX race and watch them.There is generally very little lap time wise between the 50's and the 6 speed 65's
Would probably suit the a100 yb100 more than anything else.
I think they are crankshaft mounted clutch aren't they?
It could prove a bit disconcerting on overun unit you got used to it though.
AND yes I know they are competition parts but there is a adventer model almost exactly the same only std springs instead of washers
richban
5th June 2011, 19:18
If you are a KTM dad (the Clutch) is the bane of your life if you have a 08 or earlier model,
But man does it keep them on the pipe and puts the power down like you would not believe.
Yes the are one gear but they go 0km to 55mph like you would not believe and are adjustable for kick in speed and characteristics.with special cuped washers and flat washers.
Go to a MX race and watch them.
Would probably suit the a100 yb100 more than anything else.
I think they are crankshaft mounted clutch aren't they?
It could prove a bit disconcerting on overun unit you got used to it though.
AND yes I know they are competition parts but there is a adventer model almost exactly the same only std washers
I had an adjustable clutch in my Vespa. There are heaps of options out there. I do have a dyno chart somewhere and yeh it was flat. You do need to drag the rear break a lot to get them turning in. Bit of fun but sure doesn't feel like a proper race bike.
husaberg
5th June 2011, 22:57
Less is better, we are aiming for only 2 changes per lap too, rowing the bike around with the gear leaver only slows you down I recon.
The Suzuki gp100/125s are 5 speeds (hence larger gaps between the gears)
Is that why you are concentrating so much effort on the power spread rather than outright power?
Or is it the circuit you race on is so tight? or both ?
With the 125 2s vs. 150 4s you should still almost have a torque spread advantage over the diesels but probably less overall rev range in rpm of useful power.
Wouldn’t a shallower pipe tapers give you an advantage if this is the case.
TZ350
5th June 2011, 23:15
The Suzuki gp100/125s are 5 speeds (hence larger gaps between the gears)
Is that why you are concentrating so much effort on the power spread rather than outright power?
Or is it the circuit you race on is so tight? or both ?
Both........
As I see it, at Mt Welly, easier to ride is the FXR's big advantage and outright big 2-stroke hp is no advantage at all. So our efforts with the V Tec and power range is all aimed at making an easy to ride stroker that can be turned on earlier in the corners.
There are a few things to try yet, like slippery pipe, water injection, ram tube, electric power jet carb, engine sucking through an intercooler packed with dry ice, bigger diameter rotary valve, quick shifter for the longer tracks, a dry clutch, hand made tripple ex port cylinder sleeve and maybe revisit the plenum as a way to tuck the carb and bits out of the way.
240108
The plenum was conceved at a time everyone thought a 24mm carb would be a restriction on how much outright power could be made with a 125, but a 24mm carb proved to be less of a restriction than was thought.
The plenum or a variant could still be usefull in other ways.
husaberg
6th June 2011, 09:11
[/B]
Both........
.
The plenum was conceved at a time everyone thought a 24mm carb would be a restriction on how much outright power could be made with a 125, but a 24mm carb proved to be less of a restriction than was thought.
The plenum or a variant could still be usefull in other ways.
What carb were you using? (Doh just looked at the post pic an its a keihin semi flatslide so you have got it licked)
still might be relevent for others I guess?
The bell book that was for a long time my Bible had something along rhe lines of a mikuni carbs flowing less air than the others.
Another thing that sticks in my mind that he states a smaller carb say 22 bored to 24mm will flow more than a std 24mm
Something to do with the more streamlined venturi I think.
Of couse he was dealing with roundslide carbs.
A 24mm throttle body might flow better to without the venturi.
The rules say eq to 24mm carb afterall I know other don't agree on this point though!
Maybe a cv carb might offer better low down responce can't remember them on a 2 stoke though.
husaberg
6th June 2011, 09:50
Both........
There are a few things to try yet, engine sucking through an intercooler packed with dry ice, 240108
.
have a look here http://autospeed.com/cms/A_110772/printArticle.html
IT would/could also be a very trick alternative to water cooling a barrel in combo with a water cooled head on a 100cc.
This site is one of the best resoures for all sorts of real interesting stuff.
Another thing to consider is an Marine oil cooler as an intercooler.
http://autospeed.co.nz/cms/title_The-Complete-Guide.../article.html
Buckets4Me
6th June 2011, 10:09
[/B]
The bell book that was for a long time my Bible had something along rhe lines of a mikuni carbs flowing less air than the others.
Another thing that sticks in my mind that he states a smaller carb say 22 bored to 24mm will flow more than a std 24mm
already been covered and I think it was found that a 24 could be made to flow a lot more air than anyone ever thought :woohoo:
do a search and spend a week reading this thread :facepalm: but it has been covered in detail
bucketracer
6th June 2011, 10:40
240117
Thomas did a lot of work measuring the relative air flow through various carbs and I helped him and TeeZee with modifications. Between all of us we were able to get some serious flow out of a 24mm carb.
There are 1,600 or so photos on this thread.
They can be viewed by using the Thread-Tools option near the top of this page, click View-Thread-Images in the drop down box, then the pictures can be sorted using the Display Options.
1 Thread Tools
2 View Thread Images
3 Display Options
The images can be displayed 70 at a time by using the Display-Options and clicking on the little blue N/A under an image will take you to the related post.
From page 80 all the decade pages have link collections, they were collected together as the thread went along to make it easier to find the good stuff.
husaberg
6th June 2011, 11:23
I asked Dad (TeeZee) and he said he remembers the "G"s as piston eaters, the skirt edge on the inlet side would get hammered in by the bottom edge of the extra wide inlet port. As the piston thrust side is on the same side as the inlet and the thrust tipped the piston skirt into the inlet port, pistons would have to be replaced every meeting or so.
I have just found the Yamaha twins book which covers the development of the tzs and other twins and yes it was the inlet port I offer humble apologies and grovel profusely to all.
Brain fade.
The only excuse I can offer is,
When the TZ250g/h model development was happening whist I was not pooping my pants on a regular basis I was still having the odd accident.
Looks like I still do to .
It makes more sense in hindsight to as the cylinder wall on top of the exhaust port would provide a lot of support in a forwards running engine at close to and beyond TDC.
husaberg
6th June 2011, 12:13
:facepalm:
[They can be viewed by using the Thread-Tools option near the top of this page, click View-Thread-Images in the drop down box, then the pictures can be sorted using the Display Options.
1 Thread Tools
2 View Thread Images
3 Display Options
The images can be displayed 70 at a time by using the Display-Options and clicking on the little blue N/A under an image will take you to the related post.
From page 80 all the decade pages have link collections, they were collected together as the thread went along to make it easier to find the good stuff.
Thanks for the tip makes the navigation so much easier.
I found the pages with the carb pics and the manometer testing but don't see the results maybe should pull a sicky all this week?
TZ350
6th June 2011, 22:13
I found the pages with the carb pics and the manometer testing but don't see the results maybe should pull a sicky all this week?
I don't think Thomas or Bucket posted any actual data or "results", as the manometer was only being used as a comparator and their notes would be meaningless to anyone else. There was some thought of using a rotary lobe gas meter to measure real air flow but in the end comparison with an arbitrary standard was good enough.
Although I remember that the Keihin semi flat slide was pretty good, better than the other name brand carbs of the same size and an OKO 24 (Keihin copy) machined well and could be modified to flow quite a lot of air and cheep enough to experiment with. There are probably posts about the different things that were tried.
The manometer posts were more about "for what its worth, this is what we are doing and how we did it" sort of thing, a sharing of ideas and anyone interested enough would be able to make a rig and develop their own carb setup.
Thomas would measure the gap between the upper and lower water levels (car anti freeze) in the manometer. The smaller the gap the better the carb was flowing in comparison to a std 24mm flow tube that Bucket had made. This way we were able to see what carb mods worked and which didn't.
240269 240270 a graph of Neds bike in its current trim.
As a matter of interest, NedKellys bike is still using the original 24mm GP125 carb and makes good power, the big thing was some 5mm nuts spacing the side cover off (pictured), that little trick was good for a couple of hp. The other engine details are on page 200.
2T Institute
7th June 2011, 00:20
Hmmmm, I didn't know all that goldmine of info I extracted from Frits and Jan had made it into the english speaking world.
Ah well .................................................. ..........:)
F5 Dave
7th June 2011, 11:36
Both........
As I see it, at Mt Welly, easier to ride is the FXR's big advantage and outright big 2-stroke hp is no advantage at all. . . .
Really? Nigel seems to lay waste on his 100 when he feels the desire. How often have you tried these bikes now the power is good, in decent chassis in the dry with a decent rider?
cotswold
7th June 2011, 14:11
Really? Nigel seems to lay waste on his 100 when he feels the desire. How often have you tried these bikes now the power is good, in decent chassis in the dry with a decent rider?
I know ease of use is part of the deal but I am with you I cannot see how an fxr could live with a 27hp 2 stroke in an rs chassis with a 1/2 decent rider on board.
F5 Dave
7th June 2011, 16:39
Well that 23hp curve above looks pretty easy to ride at fairly lazy revs. Perhaps this doesn't tell the full story on carburetion at other throttle positions & abruptness of Disc valve closed to open transition that on a small track may count for a fair bit if it is upsettingly sudden. I haven't ridden one. Well not for a long time & that was at Taupo over a decade, closer to two ago.
How often have you tried these bikes now the power is good, in decent chassis in the dry with a decent rider?
Ouch! note to self pull the Zarco on F5 Dave if he ever comes up this way.
husaberg
7th June 2011, 18:20
=F5 Dave;1130081035]Well that 23hp curve above looks pretty easy to ride at fairly lazy revs. Perhaps this doesn't tell the full story on carburetion at other throttle positions & abruptness of Disc valve closed to open transition that on a small track may count for a fair bit if it is upsettingly sudden
It was mentioned earlier but I can find no pics of a trial.
It cetainly make the 100cc karts user friendly not to mention the ease of tuning.
I have sampled one on a mb100 and it sure screemed but it was high side city after comming back on the power after a corner but I think I found the remedy for that later.
Although the one I tried was huge and off a jetski.
plus if you positioned it side ways it could double as the v tech valve.
Ned Kelly
7th June 2011, 19:55
Well that 23hp curve above looks pretty easy to ride at fairly lazy revs. Perhaps this doesn't tell the full story on carburetion at other throttle positions & abruptness of Disc valve closed to open transition that on a small track may count for a fair bit if it is upsettingly sudden. I haven't ridden one. Well not for a long time & that was at Taupo over a decade, closer to two ago.
Well I think I am fairly well informed to answer most questions about my bike. It does handle really well and is very driveable even at Mt Welly. My best laps to date are not up with the best but 31.6 I feel it is not all that bad for an old guy carrying a few kegs to much weight. A few of the guys have riden it and all are pretty impressed at the way it pulls out of the corners. Avalon has riden my bike on a fair few occasions and is pretty happy with it. She pushed it around to a 3rd place finish in an "A" grade race a few meetings ago, when she started from the second row. So I think that answers that question about how good it could be in the hands of a young talented rider. Now to loose some years and some weight lol:woohoo:
bucketracer
7th June 2011, 19:57
240310 240311
This is the type of pumper carb that Wobbly suggested to TeeZee that he could look at using, it has a slide throttle instead of a butterfly.
Ok, this week I have been given the job of collating the interesting links and posts from the last 10 pages.
First something for F5Dave.
If Diesels are the future then why have Evinrude , using E Tec got the lightest, most powerfull, most fuel efficient, least polluting outboard on the planet.
Yes its a 2 stroke and the only reason every 2 wheeled device used for transport isnt a 2 stroke right now, is that the technology used for effective direct injection is patented and stupidly expensive. This will change very soon and the big, heavy, slow, expensive to maintain ,polluting sacks of shit called 4 strokes, will be down the dunny along with Hondas corporate masturbation antics - exactly where both belong.
And these are at the top because we like them.
Kel's post uncovered some interesting reading:
http://www.powroll.com/Tech_crfproject.htm
Not quite what I'd do with a 80 but cool engineering anyway.....
Ive read about this motor configuration before http://vincentcrabtree.co.uk/XR200.aspx Would have been a weapon pre FXR (as far as four strokes go).
Now for the rest
As I see it, having a powerful easy to ride bike with a very wide power spread is the key to beating the FXR150's with a Stroker. As part of the plan I have been looking for a practical variable inlet and Thomas came up with a good idea.
Have a look at this idea.The Lectron carbs have a venturi behind the slide, so you get high velocity at half throttle, but actually in bench tests they flow more air than the same size PWK when wide open.
Don't raise the transfers, blowdown is most important on a motor with a single ex port and you don't want to reduce it.
Interesting bit of reading.........
http://www.saltmine.org.uk/dale/dale-faq.htm
And a down loadable PDF of Dale Alexanders work with RD's
http://www.saltmine.org.uk/pdfs/dale-faq+p.pdf
And a bit about jets thats worth a look http://home.arcor.de/martin.kieltsch/jet_size_problem_english.pdf
The RSA leads the way with the "refining" approach and its very evident that the inner radius size and angle is the key to keeping all the flow attached and heading in the right direction.
It has A port angles of 28 roof,16.5 floor. B port is 6.8 roof and 7.4 floor, Boost is 53.3 roof and 37 floor.
The flat roof B ports collide in front of the boost, this clears out allot of residuals that normally are left behind, and as these opposing flows slow down - they are pulled upward by the boost port ( its flow has already attached to the rear wall).
The A port flows over the top of the B port flow, and they all join together in the rear 1/2 of the cylinder as a slowly rising column - the famous "loop".
The idea is to create as much coherent flow entering the column as possible, and at the same time clear out as much exhaust residuals as we can, ahead of that column with no mixing.
Thus if the Delivery Ratio is high, and we keep the streams entering the cylinder "coherent" then the Scavenging Efficiency will be high.
Then if the pipe works properly the Trapping Efficiency will be high and lots of power is released.
If it all works together, then a 30+ Hp bucket is easy.
Mark the stator with a felt tip. Have your friend spin the motor over, now you should be able to pickup a spot on the rotor that matches the stator when the timing light flashes………….now you have a reference point for setting the ignition timing.
ok late enough for a musical interlude (it's been about 100 pages since the last) http://www.youtube.com/watch?v=xwhBRJStz7w
and for something completely different; http://www.youtube.com/watch?v=BXk5w91chgI
Gluing the Suzuki GP125 Engine Cases. These are the places that need gluing before porting the inlet and transfers. (check to post out to see the pictures)
Some thoughts on the over rev cough........... need to read the post to see the attached links.
…….The perfect rate of change in power is a straight line - so as you open the throttle, you get a linear change in power given.
…….. but doesn't that imply a flat torque curve (i.e. engine is operating at peak efficiency all the way through the rev range) as power is the integral wrt frequency of torque.
The new curve may not be perfectly flat, but it is certainly more efficient throughout more of the rev-range………….. FM
Dead right a flat torque curve gives a straight line power graph.
Here is sim of new F3 motor, RZ400 with around 120RWHp, near perfect throttle connection.
few interesting videos: GP125 cylinder casting by Gnani
http://www.youtube.com/watch?v=I-2rJtnkYq4
http://www.youtube.com/watch?v=Lj4h9666d9s&feature=related
http://www.youtube.com/watch?v=A50p3cg90s4&feature=related
Because a few people have asked about the GP engine, to save wading through 270 pages, these links go to the more relevant posts about the 27hp engine. Different link collections can be found on the decade pages 80-90-100.....260-270 etc.
Find tdc, then drop the piston a small amount - fill the vol to 1/2 way up the threads, move the piston up/down, till fluid sits the highest, then fill to top.
I’m not a regular on this forum but do have the occasional read. I note that this thread (& some others) have made the occasional reference to my Derbis. So I thought some of you might be interested in a bit of background. Its a long post, so pass over if you have a short attention span.……..
This is the RC Servo that I am going to use to close the V Tec below 7,000 rpm. Rotary Valve side shows the divider coming right up to the valve. In this view the valve rotates ant-clockwise. The inlet is 45 deg wide and the V Tec closes it 10 deg earlier, I would have liked 30 but this is how the first cut turned out.....
A bit on how RC Servos work........ http://www.horrorseek.com/home/halloween/wolfstone/Motors/svoint_RCServos.html#RCServo
.........it also decreases the size of the inlet tract when the inlet closing point is reduced, this keeps the inlet tract gas velocity up. I tried the RC Servo out and it opens/closes the valve OK and quickly enough
A better simple 555 RC Servo driver, parts list and construction details http://sarconastic.tripod.com/servodriver.html
OK, here is some info on how to utilise the servo option on the Ignitech............
Another method that has been used before is two intake ports and two carbs with staggered throttle opening. This also allows you to run different intake lengths and even carb bores. See Cesare Bossaglia book from early 70's for some photos of kart engines running this set up. My father in late 70's converted a 125 air cooled disc valve engine to this setup that ran very sweet and had a lot of race wins.
While searching for Cesare Bossaglia book that Sonic_V mentioned, I found this great books list on http://www.2strokeworld.com/forum/index.php?topic=2022.0
………….In a reed valve setup,tuned for peak power around 12000 rpm, we find that the best tuned length is around 135mm from the reed tip, to the end of the bellmouth works best………...
Wobbly goes into intake resonance in some depth in the above post, its worth a look.
We haven't measured ours, but I found this on the net ........... page 270 has a lot of other info too.
I made this Scatter plot in excel to give a visual depiction of the differences between a few pipes. Note the steep angle of the RS125 baffle.
That old Honda pipe mod drawing is completely useless, it was never used by the factory in any form. The rear cone is insanely steep.
And the so called A Kit pipes were designed to work with high Ex ports - where the customer engines all had 83*ATDC to let them rev without an electric powerjet.
I have much better designs with a ton of dyno time on them, but of course they are all specific to 50Hp 125 cylinders, not 30Hp 100cc designs.
Here is one that has won dozens of 125 kart titles, but again it should just point you in the right direction for the 100.
Here is the A Kit spec RS125 pipe drawing.
Expanding bellys have various effects in pipe design it allows you to increase the effect of the reverse cone, without making it shorter. It also increases the volume and can reduce the propensity of the wave to create a shock front ( killing energy) as it reverses back toward the diffuser. This is seen as a quite noticeable blip in the sim, example below seen at around 20* before TPC, of the pressure ratio at the EX port
TZ mentioned how the Honda RS pipe inlet is larger than the GP exhaust port outlet, while this is common place on 4 strokes for the purpose of AR I wasnt aware it was used on 2 strokes but on reviewing RSA photos I came across this
239992
239993
Jan Thiel "One wants the pressure wave coming back into the cilinder but NOT the burned gases that are hot and can cause detonation!"
Makes sense.
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
http://www.lortim.demon.co.uk/alpha/index.htm This is it a narrow disk valve set up, One engine used the half circle crank as the disk valve so the engine looked piston port but was disk valve. Alpha also used to do a knife edged kind of eliptical cross section streamlined shaped conrod that also looks like it would show promise as an idea in a modern engine. There is pics of about three versions of the engine here below.
There are 1,600 or so photos on this thread.
They can be viewed by using the Thread-Tools option near the top of this page, click View-Thread-Images in the drop down box, then the pictures can be sorted using the Display Options.
1 Thread Tools
2 View Thread Images
3 Display Options
The images can be displayed 70 at a time by using the Display-Options and clicking on the little blue N/A under an image will take you to the related post.
From page 80 all the decade pages have link collections, they were collected together as the thread went along to make it easier to find the good stuff.
husaberg
7th June 2011, 21:02
240310 240311
This is the type of pumper carb that Wobbly suggested to TeeZee that he could look at using, it has a slide throttle instead of a butterfly.
beautiful mmmmmmm but $$$$$$$ cha-chingggg ?shit::shit:
gatch
7th June 2011, 21:31
240310 240311
This is the type of pumper carb that Wobbly suggested to TeeZee that he could look at using, it has a slide throttle instead of a butterfly.
Where's the rest of it ?
husaberg
7th June 2011, 23:19
Just to add a little more to the intake tuning scenario,the TD and TZ piston port engines had an "insulator" spacer on the cylinder about 25mm wide.
We all thought this did what it was called ie kept heat off the carb,but no.
Shorten that spacer by 5mm and it was absolutely impossible to jet the carb.
Even blipping the throttle you saw huge standoff at the bellmouth.
Make it longer to pick up bottom end power, and for every 1 Hp gained at 8000 you lost 2 at 10000.
So again, reality fucks over theoretical analysis.
The shorter length was technically correct for the rpm,but was impossible to utilize.
Edit, the other thing I forgot to add before re Mr Helmholtz.
Its all very well making an assumption that the intake and the case vol is in fact a Helmholtz - the problem is there are 3 others doing his finest.
The case connected to the transfer ducts, the transfer ducts connected to the cylinder volume, the cylinder volume connected to the exhaust duct, and the exhaust duct connected to the pipe volume, and the pipe volume connected to the stinger.
How many did I say, anyway we have a multiplicity of ducts and volumes, trying to define one as independant of the rest is suspect to say the least.
This below was plagiarised from Design and Tuning for motocross interesting would be a good starting point still relevant aplogies if it has been covered already up to pg 70 now.
Could be a logical baseline to start testing from as most race are won on the track anyway.
Tuning of the inlet track is best resonance frequency is best done by a running test of the engine, altering the induction tract length between the intake port at the piston and the carburetor .The easies way to modify intake tract length is with a spacer blocks of different thickness es positioned between the reed valve assembly and the cylinder.
On engines without a reed valve. Induction length is critical; and carburetor manifolds of different length, positioning the carburetor closer or further away from the cylinder should be tried.
In order for the exhaust system not to effect testing of the intake tract resonance, The expansion chamber should be removed and replaced with just a short piece of header pipe, Long enough to prevent sucking of air into the exhaust port, Yet, not so long as to produce a tuning effect of its own. On 125cc engines this should be 3.5 inches long measured from the Exhaust port 4.0 inches 250cc and 4.5 inches for an 500cc bike.Testing results will probably be a compromise between of two findings concerning the inlet tract length .First, which provides the smoothest power .and the second which provides the quickest acceleration between to points measured by an observer.
For the acceleration runs, Try a rolling start from the same RPM each time and use a high gear to avoid shifting between the timed points. In most applications for High rpm a short tract works best while lower rpms and wider powerbands calls for a longer intake track length
I wish I had scaned it I type like sheit:bye:
F5 Dave
8th June 2011, 09:34
Ouch! note to self pull the Zarco on F5 Dave if he ever comes up this way.
eh? What's a Zarco? It was a fair question, these decent power figures are comparatively recent & Auckland being Auckland in Spring means many wet races.
I haven't been to any races in Auckland for about 4 years.
I would have thought these engines would Smite all but the most enthusiastically ridden FXRs & the rest down to rider ability.
I think Ned writes that Av has ridden ok to get 3rds. So who was beating her & what were they riding?
eh? What's a Zarco?
final corner 125GP Catalunya 2011
http://www.youtube.com/watch?v=KcHmdagf0IQ
ac3_snow
8th June 2011, 10:17
I think its a reference to the recent 125GP race where Zarco pushed Terrol off the track on the final corner, in the run to the flag.
Was a brilliant undertake but dirty finish, he had enough room to finish cleanly but choose not to. Penalised 20 seconds for it so didn't even get a podium after all that!
wobbly
8th June 2011, 10:51
I think we could change the unknown name of Zarco to NoMates, as Nige taught that guy everything he knows.
Bottom line with the 100cc buckets is that no matter what anyone may "think" about power/handling/ability, Nige has never once been "beaten" on that RG100/RS125 bike, he has a few titles but always he did one or more of the following -
A - crashed ( 4 year old tyres he will say)
B - crashed the opposition ( in the way he will say)
C - won easily ( nothing to do with 29Hp I gave him 5 years ago he will say)
Re the intake tuning idea of taking the pipe off - bullshit, the pipe affects the case pressure ratio, and this working with the intake length creates a tuned system.
I post again the graph of a 125 shifter engine,only change was the intake length, less 20mm, why fuck around when you get this easily seen result - 2 free Hp.
[QUOTE=wobbly;1130081602] A - crashed ( 4 year old tyres he will say) QUOTE]
Ha, my tyres are 2000 vintage meaning 11 years old (for those that cant count), pulled the bike out last night and the front was flat again, the split side walls are starting to look a little freightening, thank goodness we dont have scrutineering.
F5 Dave
8th June 2011, 12:50
Ah, can't afford Sky & certainly not the time to watch it.
Yes after my crash at Ruapuna ~ 4 years back I decided to update my front slick which was a Denis Charlet hand me down from his wildcard GP entry qualifying. in 97.
I guess it was probably past it's best by then also ~ 11yrs. Nothing to do with the snow lining the outside of the track or the fact I was off line trying to pass the 3rd placed Hoozie CBR150 on my 50. I try to work that into conversation where ever possible.
RMS eng
8th June 2011, 14:44
eh? What's a Zarco? It was a fair question, these decent power figures are comparatively recent & Auckland being Auckland in Spring means many wet races.
I haven't been to any races in Auckland for about 4 years.
I would have thought these engines would Smite all but the most enthusiastically ridden FXRs & the rest down to rider ability.
I think Ned writes that Av has ridden ok to get 3rds. So who was beating her & what were they riding?
it might be some kind of love bite,so look out Dave!
RMS eng
8th June 2011, 14:45
I think we could change the unknown name of Zarco to NoMates, as Nige taught that guy everything he knows.
Bottom line with the 100cc buckets is that no matter what anyone may "think" about power/handling/ability, Nige has never once been "beaten" on that RG100/RS125 bike, he has a few titles but always he did one or more of the following -
A - crashed ( 4 year old tyres he will say)
B - crashed the opposition ( in the way he will say)
C - won easily ( nothing to do with 29Hp I gave him 5 years ago he will say)
Re the intake tuning idea of taking the pipe off - bullshit, the pipe affects the case pressure ratio, and this working with the intake length creates a tuned system.
I post again the graph of a 125 shifter engine,only change was the intake length, less 20mm, why fuck around when you get this easily seen result - 2 free Hp.
and also shit its self at 2 GPs
F5 Dave
8th June 2011, 17:19
Change of lean needle jet should have resolved that. If he can race next GP my money would still be on him.
ac3_snow
8th June 2011, 17:22
I would like to meet this mysterious Nigel fellow. lets hope we can have GP this year, theres alot of people would like to put faces to.
jasonu
8th June 2011, 17:24
Change of lean needle jet should have resolved that. If he can race next GP my money would still be on him.
My guess was the cylinder liner ex bridge pinched up
Nigel has been at the last couple of Mt Welly practice days. Short guy with a seriously fast 100. He's the "fast two stroke" that goes past in Javawockys first video from the May meeting.
ac3_snow
8th June 2011, 17:48
Nigel has been at the last couple of Mt Welly practice days. Short guy with a seriously fast 100. He's the "fast two stroke" that goes past in Javawockys first video from the May meeting.
Ahh righto I had been checking out Damian's pictures and spotting a heap of people there on the Saturdays that I haven't seen on a Sunday.
I plan to actually be there this Saturday so will see for myself.
ajturbo
8th June 2011, 18:05
would any of you guys know what the timing should be for the GT125 twin?
or how i would find out?
thanks..err wont be here this weekend ..
AJ
diesel pig
8th June 2011, 18:19
would any of you guys know what the timing should be for the GT125 twin?
or how i would find out?
thanks..err wont be here this weekend ..
AJ
22 degrees BTDC or 1.93mm with the dial gauge
wobbly
8th June 2011, 19:30
Na, the tuning issue with the RGV100 was twofold for Nigel, the needle and tube were always too lean, and it would sieze when backing off for the downchange.
And having been run for 3 years untouched, the bridge had worn way past the spec.
Its now got a tube that works, and has had the iron bore plated, so the wear issue has gone as well.
goose8
8th June 2011, 19:32
I have beaten Nigel in 4 or 5 points racers at mt Wellington with only 17hp an a 30 year old frame not to hard to beat that bike but at taupo 10 extra hp an a grand prix frame not so easy.
bucketracer
8th June 2011, 20:16
As I see it, at Mt Welly, easier to ride is the FXR's big advantage and outright big 2-stroke hp is no advantage at all.
So our efforts with the V Tec and power range is all aimed at making an easy to ride stroker that can be turned on earlier in the corners.
I have beaten Nigel in 4 or 5 points racers at mt Wellington with only 17hp an a 30 year old frame not to hard to beat that bike but at taupo 10 extra hp an a grand prix frame not so easy.
Looks like goose8's experience is pretty much in line with TeeZees assertion that outright hp is not that much help at Mt Welly and that easy to ride power delivery may be a good thing to aim for on Mt Wellys tight track.
A good rider and easy to ride bike are hard to beat there..............
ajturbo
8th June 2011, 20:16
22 degrees BTDC or 1.93mm with the dial gauge
Thanks so much..:woohoo::woohoo::woohoo:
Buckets4Me
8th June 2011, 20:18
I would like to meet this mysterious Nigel fellow. lets hope we can have GP this year, theres alot of people would like to put faces to.
ha ha hope you like grass or tyre wall :facepalm: there is a reason he is called nomates
but what a show. cant count the number of times he has pased me on the grass with the throttle peged open
speedpro
8th June 2011, 21:18
Nigel's bike has a very nice spread of power. Don't be fooled by the peak power it makes tricking you into thinking it is a peaky monster.
husaberg
8th June 2011, 21:54
Re the intake tuning idea of taking the pipe off - bullshit, the pipe affects the case pressure ratio, and this working with the intake length creates a tuned system.
I post again the graph of a 125 shifter engine,only change was the intake length, less 20mm, why fuck around when you get this easily seen result - 2 free Hp.
Don’t be mean wobbly you will hurt my feelings.:confused:
This below was plagiarised from Design and Tuning for motocross interesting would be a good starting point still relevant aplogies if it has been covered already up to pg 70 now.
Could be a logical baseline to start testing from as most race are won on the track anyway.
Tuning of the inlet track is best resonance frequency is best done by a running test of the engine, altering the induction tract length between the intake port at the piston and the carburetor .The easies way to modify intake tract length is with a spacer blocks of different thickness es positioned between the reed valve assembly and the cylinder.
On engines without a reed valve. Induction length is critical; and carburetor manifolds of different length, positioning the carburetor closer or further away from the cylinder should be tried.
In order for the exhaust system not to effect testing of the intake tract resonance, The expansion chamber should be removed and replaced with just a short piece of header pipe, Long enough to prevent sucking of air into the exhaust port, Yet, not so long as to produce a tuning effect of its own. On 125cc engines this should be 3.5 inches long measured from the Exhaust port 4.0 inches 250cc and 4.5 inches for an 500cc bike.Testing results will probably be a compromise between of two findings concerning the inlet tract length .First, which provides the smoothest power .and the second which provides the quickest acceleration between to points measured by an observer.
For the acceleration runs, Try a rolling start from the same RPM each time and use a high gear to avoid shifting between the timed points. In most applications for High rpm a short tract works best while lower rpms and wider powerbands calls for a longer intake track length
I wish I had scaned it I type like sheit
The post did not say to run without a pipe just a neutral length one .
The theory is to eliminate to pipes effects so as to find the true best intake length no one denies the pipes effect on the intake this test is only to separate them before trialing the expansion chamber.
Note not everyone as access to a dyno.
Have you tried the idea?
Don’t find Fault find a remedy Henry Ford
He to had a couple of crazy bullshit ideas to weird thing is most people only remember his one great one aye?
Do you keeep in touch with Bud Askland I am guessing you would have worked with him Woobly?
Below is another of Jim Gianatsis other bullshit Ideas I am not kidding its the same bloke who had both ideas!
[B]Whats your opinion on theone on the right I think maybe if I added a few inches I would be able finish before her.
wobbly
9th June 2011, 08:43
In a discussion with Thiel he said he tried an RSW with no pipe ( no expansion chamber) it took days to get the ignition curve and the jetting to work at all,cant remember what the power was ( 20% I think).
So you have an engine that makes 12Hp at 8000 rpm and that is supposed to help you ascertain the correct intake length for an engine that makes 55 at 12800 - Puleeeease.
It would be like taking the tits off the girls to see if you still got it up.( Max the Emperor would)
I worked with Bud when making pipes for several teams, and spent ages in his dyno/container office.Very clever guy that was using a 3D - CNC anemometric flow visualiser on cylinders before anyone knew what they were.
He offered his services to Bill for 1Mill to design the BSL cylinder,I got the job for only a little less.
I have keep in contact with his brother, who was the Roberts crew chief.
Re Nigel getting beaten, im sorry, for some reason I wasnt told about that suicidal nightmare.
He has just told me that in his efforts to stop the mystery siezing he had cut the com from 16:1 to around 14:1 and retarded the timing heaps, so it would be lucky to make 20Hp.
Now all that is solved he is going for an Ignitech and dead straight intake with powerjet carb.
Be over 30 easily, once the head is redone.
F5 Dave
9th June 2011, 12:01
Looks like goose8's experience is pretty much in line with TeeZees assertion that outright hp is not that much help at Mt Welly and that easy to ride power delivery may be a good thing to aim for on Mt Wellys tight track.
A good rider and easy to ride bike are hard to beat there..............
I don't think that backs the theory directly at all. That says that a good rider is paramount.
Also no one rides or has their best day every day they go out.
When I last rode Nige's bike it was running pretty averagely, & seat of pants I would have said 18hp. He took it home, found some issue (can't remember) & won the GP the next day. I saw the race & he rode clean & well. But the bike looked fast.
TZ350
9th June 2011, 16:11
Chambers sent me this link for those that might want to find a suitable rod, and I think they will even make you one to order.
http://www.samarin.net/?productos
TZ350
9th June 2011, 16:23
Hmmmm, I didn't know all that goldmine of info I extracted from Frits and Jan had made it into the english speaking world.
Ah well .................................................. ..........:)
I am glad you got them talking, I recently stuffed up my password or forgotten it and now can't get back on and view the pictures. Anything you wanted to post would be welcome.
TZ350
9th June 2011, 17:26
240408 240407
Finaly got the V Tec working..............
240406 closed 240405 open
RC Servo, Servo Tester, Signal Reverser and Com/NO/NC relay that the Ignitec can activate.
Video of the V Tec in action http://www.youtube.com/watch?v=FeB9O6rtLXQ
Next step is to fit it to the bike, wire it up so that it opens at 7,000 rpm and see how it all goes on the dyno.
2T Institute
9th June 2011, 21:15
I am glad you got them talking, I recently stuffed up my password or forgotten it and now can't get back on and view the pictures. Anything you wanted to post would be welcome.
No need for me to post anything Wobbly's doing a great job already
Moooools
9th June 2011, 21:27
240408 240407
Finaly got the V Tec working..............
240406 closed 240405 open
RC Servo, Servo Tester, Signal Reverser and Com/NO/NC relay that the Ignitec can activate.
Video of the V Tec in action http://www.youtube.com/watch?v=FeB9O6rtLXQ
Next step is to fit it to the bike, wire it up so that it opens at 7,000 rpm and see how it all goes on the dyno.
Ahhh. The simplicity of two strokes. So few moving parts. :facepalm:
husaberg
9th June 2011, 22:28
In a discussion with Thiel he said he tried an RSW with no pipe ( no expansion chamber) it took days to get the ignition curve and the jetting to work at all,cant remember what the power was ( 20% I think).
So you have an engine that makes 12Hp at 8000 rpm and that is supposed to help you ascertain the correct intake length for an engine that makes 55 at 12800 - Puleeeease.
Your post actually got me thinking about something else about pipe acoustics, Something I struggle to get my head around is this.
As I understand the negative wave as well as drawing more fuel air in during the normal indution cycle can also keep a reed valve open to draw in more fuel air mix.
But in a rotary valve engine the inlet is positively closed does this mean a properly designed exhaust would have less effect on a disk valve engine. Or just it will influence over less time with a stronger pulse Are expansion chamber characteristic/perimeters different for Reed vs. Rotary valves?
! million to design the clinders? Sounds like a lot but if you think about it another way its only $333333.33 each
Regarding the breasts cut the breasts off and yes I would still go there, I am a little sadistic though.
I believe one of the other gp racers of the period was even less discerning and had a interesting lady boy encounter which was quite a sore point for a number of years was it lC?
:innocent:
"There are more than one way to skin a cat
Some ways may work better than others,
Some people may think other peoples methods are crap ideas.
But your kidding yourself if you expect the cat to be happy about any of them"
wobbly
10th June 2011, 09:08
Well thats one of those old wives tales ( or tuners tale if you like).
The depression created in the case by the diffusers outgoing + wave,sucks like hell on the cylinder, via the Ex duct, around BDC.
That is, if its properly designed for maximum effect at peak torque.
There is simply insufficient time for this effect to suck mixture thru the transfers, empty the case, and then start sucking the reeds open.
It just doesnt happen.Its lies, a myth,not reality at all.
And to make it worse, if the diffuser is designed correctly, when it works best, there is the least time period ie full noise.
In a race engine at peak torque (same as peak power in many cases)the reeds do not start to crack open until the piston is travelling upward and is covering around 1/2 the transfer height.
So in this respect this is about the only similarity a race engine has with your dads old lawnmower,in that the rising piston creates some of the depression needed to initiate intake suction.
As I have posted before,this can be "tuned" in as much as correctly timing the wave return at the reeds as + just as the case starts to go -, you create the max effect possible by using free energy to open the reeds.
Sure, the better the pipe, the sooner the case goes below a zero pressure ratio, and this has only a minor effect on the reed opening point - but there is NO FLOW created by the pipe "sucking" on the reeds, its bullshit.
Rotary valve intake tuning is highly affected by resonance effects due to the very "sharp" open/close scenario,creating high amplitude "shock" and standing waves in the carb - but inherently the pipe is working with the cylinder contents, not the case vol, and thus the design parameters are to all intents identical.
Look again at the F3 engine I am building - the reed tip lift is only just starting to allow real flow, when the transfers are closed.
When in full resonance mode ( in this case its designed to work best in the overev ) the reeds open a little earlyer, and stay open alot longer due to intake "ram" but there is little evidence of pipe effects, even the reed closing side of the trace has nothing to do with "pipe suction"..
F5 Dave
10th June 2011, 10:08
. .
There is simply insufficient time for this effect to suck mixture thru the transfers, empty the case, and then start sucking the reeds open.
It just doesnt happen.Its lies, a myth,not reality at all.
. . .
Ooh I love a good sweeping statement. Actually I'd expect this is true, it makes perfect sense.
ok but as a side argument of a slightly different scenario, starting with an old Cameron article he was on about some tests McCulloch or some crowd were doing with high speed cameras & windows in the reed chamber. Their observation was of the intake phase completing & the reeds closing. Later the upper middle finger opened again & fed the boost port. That would tend to indicate;
1. that they weren't working on a chainsaw engine unless it had a 6 petal reedblock fitted to it.
2. the reed was responding to pressure difference in the cylinder.
So the crankcase didn't have to be involved directly. So would you say this reputed direct feed is an exception? Or that it wouldn't happen on a real race engine? Or they didn't interpret it correctly & there was some other reason?
I'm presuming the info to create these sims must come from observation of engines & localised pressure measurement & high speed video. Having trawled through some of the SAE & Belfast stuff I suspect getting those numbers is 9/10 extremely boring with the tid bit of hey this is really good.
wobbly
10th June 2011, 11:15
Only the middle reed opened - wow, a real odd artifact you would never expect,but that sort of shit happens all the time.
I would get a migraine trying to fathom that one.
One other point to mention here, one I have posted before somewhere.
If you look at the delivery ratio of a race engine, then calculate how much actual mixture is transmitted thru the transfers into the cylinder - compare that to the swept vol of the transfers, you realize that in most engines,what is sitting in the ducts is more than the vol going to the cylinder.
So where is all this so called case flow that supposedly opens the reeds, it aint there at all.
This is why new technology has the transfer ducts getting smaller and smaller,the stored volume has less inertia and gets into the cylinder quicker with the same pressure ratio across the ports.
F5 Dave
10th June 2011, 14:48
Oh boy & on a friday afternoon you have me having to think?
Wouldn't the boost port act like a vacuum cleaner pipe aimed at a stack of leaves? A localised suction of the closest leaves, meannig the middle upper finger reed would be affected by the boostport. Perhaps. Hey just shooting the breeze.:blink:
. . .
If you look at the delivery ratio of a race engine, then calculate how much actual mixture is transmitted thru the transfers into the cylinder - compare that to the swept vol of the transfers, you realize that in most engines,what is sitting in the ducts is more than the vol going to the cylinder.
. . ..
erm, presumably pressurised in the ducts flowing into a what becomes a vacuum & hopefully still flowing as pressure rises with inertia. Is the volume comparable?
Don' you want the inertia to continue filling?. On the other hand if you have mega flow area then the transfers close before they used to have to.
husaberg
10th June 2011, 23:26
This is why new technology has the transfer ducts getting smaller and smaller,the stored volume has less inertia and gets into the cylinder quicker with the same pressure ratio across the ports.
Wouldn't the increase in velocity balance the decrease in volume (mass) so the inertia be the same.
What basic bit am I missing.:gob:
ps what did you think of the alpha conrod any merit for a reed engine?
never seeen a yzr rod but i guess they pretty much looked pretty much like any other.
Also did any other Gp teams use slave engines like buds old test mules?
I have a good job.
I pay my taxes.
Part of my taxes goes to support the unemployed.
I am ok with that it kind of makes me feel good about the world and all.
As part of my job I have to submit to random drug testing
I am ok with that too because life’s depend on me doing my job well.
But why is it the recipients of my tax money don't have to do a drug test before they get my tax money.:violin:
Henk
11th June 2011, 08:13
I'm guessing that the decrease in volume does lead to a decrease in mass and therefore inertia leading to an increase in acceleration of the charge.
The lost volume if I'm reading this thread right is gas that can't be accomodated in the cylinder anyway so you aren't trying to moving gas that that can't be used in any case.
husaberg
11th June 2011, 09:02
I'm guessing that the decrease in volume does lead to a decrease in mass and therefore inertia leading to an increase in acceleration of the charge.
The lost volume if I'm reading this thread right is gas that can't be accomodated in the cylinder anyway so you aren't trying to moving gas that that can't be used in any case.
Sorry Henk.
I am still not quite getting it
Surely these left over gases lurking arround in the transfers contribute to the first part of the charge for the next revolution or are we trying to minimise this because it has a some kind of stalling effect because the charge has to be accelerated again?Or is this charge lost in the pipe and not rammed back because its to early.Wobbly should be able to correct my faulty underdstanding of this I hope.:confused:
i understand the f=ma stuff but wobbly didn't quite say this i think. but I will re read his post - beer fog input
Just re read - fog and I think he is say newer versions have smaller transfers so they have to use less force to acelerate the charge and there for will maintain a higher velocity?
I'm guessing that the decrease in volume leads to a decrease in mass giving an increase in acceleration of the charge.
So early development of the 2 stroke was about pressure ratio to give good cylider filling?
Later it was tried to get a good (volume) mass of mixture to flow .but it lead to, too much pumping losses?
And now its all about a fast velocity of fuel air charge and at the same time to lowering pumping losses by running a low presure ratio.being more effiecient.
Yow Ling
11th June 2011, 20:04
Seeing as this is the thread for engine development stuff, I thought I would add a bit more about my Moto4 Engine
I had to cut the kickstarting stuff off the back of the engine so it would fit in the RS125 frame, I took it to the leading bucket welding tech in Christchurch, Darryl Cotton at Advanced Autohomes to have the gash patched up. Ready the next day. Cost $42 cheaper than getting tyres changed at Haldanes.
Just needed to tidy up the mating surfaces, after a bit of head scratching I came up wuth a setup that would work. Cases tidied up ready for the stuffing everything back in stage, which is tricky because its over a year since I unstuffed it.
Heres a few pics of the machining work, not sure about the order
TZ350
11th June 2011, 20:12
I had to cut the kickstarting stuff off the back of the engine so it would fit in the RS125 frame.........
Interesting to see the progress, and whats needed to get the RG100 into the RS frame .........
Yow Ling
11th June 2011, 20:19
Oh yea , ordered a piston the other day from Strike in perth, somebody posted a link on this thread . They make a range of pistons for yamaha Kart engines. Normally KT100 pistons start at around 52mm but they make pistons starting at 50.00mm for the junior classes, I ordered a 50.6mm so will end up at 101.75cc, oversizes are tiny so you only need to hone to the next size. About NZ$100 for a piston. Built a crank a couple of weeks ago, motivation is high , very cold in shed tonight !
TZ350
11th June 2011, 20:29
Built a crank a couple of weeks ago, motivation is high , very cold in shed tonight !
More photos, as it progresses please................... very interesting project, its good to know 50+mm pistons are available too.
Kickaha
11th June 2011, 20:32
very cold in shed tonight !
Wrap yourself in a tyre warmer and plug it in
F5 Dave
11th June 2011, 20:54
Thanks for the info re the pistons
So you have a coach builder weld up your engine? Gee you SI guys are rough.
I've done the same on several engines, but use Devcon etc as required to help stave off distortion.
That being said he's a top bloke & welding I've seen is good work indeed. Pity DC doesn't make it on here, look forward to catching up with him hopefully at the next BOB.
TZ350
12th June 2011, 20:43
Interesting Kiwi invention, a 2-Stroke engine with no conrods or traditional crankshaft.............
Web page http://www.shepherdengine.com/our_technology/index.html
U tube Startup demo http://www.youtube.com/watch?v=6WN_ziute-c (http://www.youtube.com/watch?v=6WN_ziute-c)
TZ350
13th June 2011, 21:58
240724
I didn't have much luck with the V Tec tonight, it all tested out OK and I could toggle the valve open and closed using the Ignitec ignitions test program.
But when the motor was running the RC Servo would jiggle all about and not hold the valve properly closed but when it hit 7,000 rpm its change point the servo would quickly open the valve and hold it there.
After some thought I think the problem is with the signal reverser, I think it is picking up noise and I will have to replace it with another servo tester, so that I have positive drive open from one tester and positive drive closed with the other.
240722
But we did find something interesting, the soft close rotary valve (starts at 70 finishes at 80) red line seems to give more over rev and marginaly more hp and the disk that closes at 85 atdc gave a little more drive and less hp, the reverse of what I was expecting.
240723
Soft close on the right.
Buddha#81
14th June 2011, 07:44
Thanks for the info re the pistons
So you have a coach builder weld up your engine? Gee you SI guys are rough.
I've done the same on several engines, but use Devcon etc as required to help stave off distortion.
That being said he's a top bloke & welding I've seen is good work indeed. Pity DC doesn't make it on here, look forward to catching up with him hopefully at the next BOB.
you wont speak to him now.......finally he has seen the light and now owns a FXR, Bwahahahaha.
ac3_snow
14th June 2011, 20:51
Pratley steel putty, $10 for 125g.
Used this stuff to 'glue' my reed valve in place, perhaps not an ideal use as it failed after a days running. Is still holding strong where I used it to fill in the crank case however.
240722
240270 a graph of Neds bike in its current trim.
As a matter of interest, NedKellys bike is still using the original 24mm GP125 carb and makes good power
I have been tossing up about buying a new carb, currently running a standard mikuni roundslide 24. After seeing what Ned's bike can do, I have my doubts as to wether it would be money well spent.
I have heard from FXR riders that a better carb might help make a little more power low down, and comparing dyno charts between TZ and Ned's engines it may be true.... or this could just be the porting differences?
Buckets4Me
14th June 2011, 20:59
I have been tossing up about buying a new carb, currently running a standard mikuni roundslide 24. After seeing what Ned's bike can do, I have my doubts as to wether it would be money well spent.
I have heard from FXR riders that a better carb might help make a little more power low down, and comparing dyno charts between TZ and Ned's engines it may be true.... or this could just be the porting differences?
240782 this looks like the business
240783 found this under a bench at E.S.E
bucketracer
14th June 2011, 21:33
I have been tossing up about buying a new carb, currently running a standard mikuni roundslide 24. After seeing what Ned's bike can do, I have my doubts as to wether it would be money well spent.
Neds is still running the original 24mm round slide Mikuni,(with a re shaped bellmouth). Thomas's bench tests with the manometer showed that the OKO 24 that we had flowed a small but significant amount more than the Mikuni. If your going to buy a carb an OKO might be a good buy and cheap enough for a new carb.
The exhaust ports are much the same, the big difference in porting between Neds and TeeZee's is mostly in the transfers, TeeZees are low and wide to maximize the blowdown time area. Neds barrel is an early Team ESE effort and was lifted 1.5mm to get the transfer time area required but that approach limited the effective blowdown time area that is possible and that (probably other things as well) limits the power.
TeeZees carb is a 24mm flatslide but the inlet timings are the same as Neds, the real induction difference is the inlet port size, TeeZees has been enlarged as much as possible, Neds is still pretty much standard with a clean up.
The pipes are different too, Neds is a RM copy and TeeZees is an old Honda RS125 pipe.
husaberg
14th June 2011, 23:17
Interesting Kiwi invention, a 2-Stroke engine with no conrods or traditional crankshaft.............
2 strokes are supercharged anyway so why not give them a bit of extra boost should help the low down power a bit.
Might want to trim the port timings a bit:lol:
bucketracer
14th June 2011, 23:28
240783 found this under a bench at E.S.E
Thomas and TeeZee spent a lot of time looking at carbs, I think they have some ideas about making their own if they ever need to, or commissioning a short run of 24mm OKO's finished to their own design and sold over the net.
The OKO 24mm flat slide is nearest the engine and Neds Mikuni that was re shaped with Devcon, is the one closest to Thomas.
bucketracer
14th June 2011, 23:36
2 strokes are supercharged anyway so why not give them a bit of extra boost should help the low down power a bit.
Might want to trim the port timings a bit:lol:
From what TeeZee says, old supercharged motorcycle 2-strokes were thirsty beasts but you would think with water cooling and modern direct fuel injection into the cylinder, they could be really good.
F5 Dave
15th June 2011, 09:32
Used this stuff to 'glue' my reed valve in place, perhaps not an ideal use as it failed after a days running. Is still holding strong where I used it to fill in the crank case however.
Depending on the setup you can use Devcon to glue inlets on. My RG50 had a (piston port) spigot shape into a round loose bore glued & it never failed after many many years. Think the current one is just a plate glud on with Devcon too. I've done reedblocks but got them tacked on the corners for strength & then glued the rest together. Less chance for distortion that way.
How you use it is important. Clean surface properly & some centre punch indentations to 'key' into if needs be.
Have used Devcon a lot & JB Weld seems good too. Never tried your stuff.
Kneedit has it's place, but only as a filler, not to attach with any strength or withstand heat etc.
ac3_snow
15th June 2011, 09:45
If your going to buy a carb an OKO might be a good buy and cheap enough for a new carb.
So the powerjet versions don't need a fancy ignition to control them, you can run them on any bike?
How you use it is important. Clean surface properly & some centre punch indentations to 'key' into if needs be.
Have used Devcon a lot & JB Weld seems good too. Never tried your stuff.
Kneedit has it's place, but only as a filler, not to attach with any strength or withstand heat etc.
Yea the Pratleys is a bit like Kneadit. Will try again using JB weld/Devcon and drilling/punching keys as you say. Tacked on sounds like a good idea, bit more difficult to get done.
Its to hold a modified crankcase reed in place, I'l try put up a pic later.
So the powerjet versions don't need a fancy ignition to control them, you can run them on any bike?
Yea the Pratleys is a bit like Kneadit. .
If you mean the OKO power jet then no ignition interface is required, they work on the vacuum at high velocity principle.
Pratley is a putty and needs to really be worked on to the surface i.e. smearing with some force. I roughed up the surface with the grinding tips to give kind of golf ball indentations, seems to have held but then my motors not running yet!
F5 Dave
15th June 2011, 10:43
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.
wobbly
15th June 2011, 19:08
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.
richban
15th June 2011, 20:26
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.
No matter how much power you have, or how peaky or not the engine. I would think you would want to gear the bike to use the full gear box spread for any track. You don't want to be waiting around for the power to build. You want it all in your hand when ever you twist the throttle. We are not talking about 200hp here. Crack it open and smile.
Small disclaimer. I seem to hold the record for most high sides on a bucket in wellington. But don't let that stop you from cracking on the power in the most violent fashion physics allow. You will get the the next corner quicker I promise.
Problem solved.
Now pack you your bikes and come down to wellington this weekend for some racing.
koba
15th June 2011, 21:17
Small disclaimer. I seem to hold the record for most high sides on a bucket in wellington. But don't let that stop you from cracking on the power in the most violent fashion physics allow. You will get the the next corner quicker I promise.
That last crash when I almost ran you over was quite spectacular...
Henk
15th June 2011, 21:36
Now pack you your bikes and come down to wellington this weekend for some racing.
Oh all right then, if you insist, you're not going to call the day off because of crap weather or some other weak excuse are you?
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