ESE's works engine tuner

[ken seeber]

Kentastic had designed something very similar ( in aluminium ) for KZ2 some time ago , sadly having a business that makes money is strangely more important.

Ahah WWW, would you be referring to that piston design which was/is novel, lighter, stronger and more durable? :yes:

Unfortunately though, nothing strange going on here. :(

[Frits Overmars]

Do you have any photos of the Suzuki RK67? I am after a photo of the underside, which shows all the cooling fins
349908 349909
Underside-pics are rather rare; this is the best I can do.

[Muhr]

I have been thinking a bit about making a piston in Inconel or some other high nickel alloy. fumbled a bit in the computer but feeling that succeeding in doing something that could be good is a challenge ... will be a little easier to find benefits if the piston gets bigger (or at least bigger than 50cc that I looking at)

[wobbly]

Muhr , I think one important element of a " better " piston design is hinted at in the lovely 4T pics , and from what I can remember about new Ken's proposal is that
the pin boss in the piston only needs support at its ends , not along its length ( not even with the small triangle as you have shown ). Having one end supported by the skirt , and the other
end held by a thin flat support directly up to the dome does double duty. This can be extended in a bigger piston, in that the pin does not need to go anywhere near as wide as the skirt , but can be supported
again at each end with a thin flat support up to the dome.

[Flettner]

I'll ask the CNC nicely if it might unprint a piston from this steel bar for me. Actually a composite, not the complete piston.
48mm dia.

[ken seeber]

Muhr , I think one important element of a " better " piston design is hinted at in the lovely 4T pics , and from what I can remember about new Ken's proposal is that
the pin boss in the piston only needs support at its ends , not along its length ( not even with the small triangle as you have shown ).

As with just about everything, it turns out it isn't unique. That good man Frits posted a pic of a design that was very similar. It's somewhere here within ESE. Happy searching.

[husaberg]

Do you have any photos of the Suzuki RK67? I am after a photo of the underside, which shows all the cooling fins

Sorry no
1 a 3/4 at best
Hugh Anderson had one here for a while

............


https://www.youtube.com/watch?v=PcRWO-jvjDI

While we are waiting here is the one Hugh Anderson had here and sold to I think the Netherlands.
https://www.kiwibiker.co.nz/forums/showthread.php/151865-Old-multi-cylinder-bikes-of-the-50s-to-later-on-Japanese-British-Euro-etc?p=1130374843#post1130374843

https://www.kiwibiker.co.nz/forums/showthread.php/151865-Old-multi-cylinder-bikes-of-the-50s-to-later-on-Japanese-British-Euro-etc?p=1130616443#post1130616443

https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=288082&d=1380532376

https://www.kiwibiker.co.nz/forums/showthread.php/151865-Old-multi-cylinder-bikes-of-the-50s-to-later-on-Japanese-British-Euro-etc?p=1130618964#post1130618964

Elsberg has pics of the 3 underside and others.
http://www.elsberg-tuning.dk/suzuki.html

looking at a picture i found it looks like the Jaoanese publication the racer may have done a story on it with drawings
https://lh3.googleusercontent.com/proxy/DZp9k4uTDNQDtsii-_TeUlXbMMlvpbKe8eA21nsqxoR-OEEhOC5JYFcDREQpSg_8xd28mCgiQfVwZfYz60HecWHtb-a-INmx7Ia3gxKkGYXX16Z_77bhWjK6VEQTobA_wP126Jqf1ue_Ye TYUJrpesQwf45xEm7v6nLkU4Y1DTjqgigFynCEJDh7o6yzPkCX lXmlsl8r9eg_eFg
https://www.youtube.com/watch?v=79xuDS9l8vI
protar have kits as well it seems

it looks like the Lexmond Museum has one in the NetherlandS?

is this you
https://www.youtube.com/watch?v=79xuDS9l8vI
https://www.youtube.com/channel/UC1fx38XpD4W13sxnzfWBKtA

[speedpro]

. . . 48mm dia.

flash new FZR250 pistons?

[Frits Overmars]

As with just about everything, it turns out it isn't unique. That good man Frits posted a pic of a design that was very similar. It's somewhere here within ESE. Happy searching.Here you go, Ken & Muhr. A high pin, because most of the piston mass is between the pin bosses and the crown, and a high pin makes for a lighter construction.
Direct support from the crown center to a short pin and direct heat paths from the crown center to the bearing areas of the skirt.
349924

[Muhr]

Yes my attempt is certainly no masterpiece, had a hard time not getting any ovality under heat and load.
with a lot of testing, you should get closer to 0.01 piston clearance, and then have to preheat the engine before starting. Which would be pretty racing.
With 5-10% of the thermal conductivity and almost a third of the expansion, you can probably encounter several interesting consequences

[katinas]

Here you go, Ken & Muhr. A high pin, because most of the piston mass is between the pin bosses and the crown, and a high pin makes for a lighter construction.
Direct support from the crown center to a short pin and direct heat paths from the crown center to the bearing areas of the skirt.
349924

Maybe even this helps to keep the engine operating temperature some degrees lower, without the risk of piston seize.
Before this year testing with directly through transfers intake configuration, on Honda RS 125 cylinder, I am worried about higher expansion 2618 alloy special piston in comparison with Honda RS origin.
But the biggest surprise was opposite results. 2618 alloy piston with inner walls, surprisingly worked from 38C to 44C temperature without signs of seize. Then first ride with std intake configuration and original Honda RS piston at this temperature, ended with slightly jammed piston ring on EX side. This repeated more or less every time with Honda pistons until I covered part of radiator with tape and operating temperature rises to 50C - 58C.

[andreas]

Katinas, what an intriguing piece. How does that transfer-shortcircuit-passage work, looks as if it's covered by the skirt at bdc?

[ken seeber]

Try as they might, these misguided 4 stroke guys have gone to a lot of trouble to try to emulate Fletto's sliding gibs. Must say this one's quite clever though. :)

https://www.roadandtrack.com/new-cars/car-technology/a31224648/hyundai-cvvd-system-explained/?utm_medium=social-media&utm_source=facebook&utm_campaign=socialflowR%26T&fbclid=IwAR0GSxmlNzbTlgBwDoQCXI6_2Txh_jljWqW69dgeC MiloZUjLt8FOv0E50Y

[F5 Dave]

A 4% increase in power? Wow that's a game changer. Probably get that much variation between production engines.

[katinas]

Katinas, what an intriguing piece. How does that transfer-shortcircuit-passage work, looks as if it's covered by the skirt at bdc?

Andreas, actually this is two intake passages opens and closes at the same time with A and B that works like intake ports too (intake duration through this six ports 206 degrees)
This passages compensate intake restrictions of A, that was partly covered by the piston skirt due to overlap of two exhaust port configuration of the Honda RS cylinder and not needed for narrow one exhaust port type.
This passages only works with intake through transfers configuration, but useless or destructive for normal intake/scavenging type.

[andreas]

Oh, it's a more complex engine, I see.

[speedpro]

A 4% increase in power?

The Toyota 3.5L V6 I have has cam timing that varies about 40 degrees on both intake and exhaust cams. The peak could be higher I suppose but the spread is what makes it a great engine. I've driven a Holden ute with a LS 5.7L and they are surprisingly similar. Both rated at about 300hp. Point is that peak hp isn't everything.

[philou]

I'm looking for the rotax 256 workshop manual.

do you know where i can find it?

[andreas]

I'm looking for the rotax 256 workshop manual.

do you know where i can find it?

http://www.artmotorsport.com.au/new/Rotax%20Manual%20Pt1.pdf

[philou]

http://www.artmotorsport.com.au/new/Rotax%20Manual%20Pt1.pdf

this is not the workshop manual. just the parts list.

[TZ350]

<iframe width="560" height="315" src="https://www.youtube.com/embed/gHeY-bMnEoE" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>

2STROKE STUFFING gives a really good explanation of the theory behind his project.

What is needed now is one good, problem free run with the supercharged externally scavenged 50cc nitro concept engine. Did it happen?

[TZ350]

.

2Stroke Stuffing is building a dyno to test the supercharged 50cc engine. https://youtu.be/9agOt7QbR0c

.

[Henrik Y]

Hello, I'm going to share some pictures of my Suzuki GP build that I've been working on over the last 1½ years. I'm partially paraplegic after a paragliding accident in 2016, I can stand with support but use a wheelchair for all my daily movements but it is enough for me to be able to sit on smaller light weight bikes and balance them with my legs so that's why I got this bike.

10 years ago I thought cafe racers where cool but now I've got quite feed up with them and puke as soon as I see one of those generic cafe racer seats from ebay. So instead of that I skipped the coffee and went full fairing vintage racer instead.

One of the first test rides.

https://www.youtube.com/watch?v=bwh1R_lsRn0

[Henrik Y]

The bike was a wreck ready for the scrap yard when I got it, the frame was broken and swing arm where so worn the rear wheel could move like 20mm side to side. So first thing I had to do was fix the frame, cut out the broken parts and weld in new material. I did also add extra tubes and stiffened the frame.

I started making the fuel tank just to see if I could pull it off or not and if it turned out okay I knew I could get on with the build and order a fairing and such. It wasn't easy having nowhere to be but outdoors, setting up wind covers when welding and having to pack up if there was any risk for rain.

[Henrik Y]

The swing was so worn that the rear wheel could move like 20mm side to side, I can't understand how they where able to even ride this bike in the past along with the broken frame. But then it hasn't been in traffic since 1992.
I cut of the old bushings and replaced them with KTM 65cc swing bearings. And then I made bushings to press into the frame that I drilled out as it was worn as well from the swing bolt.

Then I ordered a VMC ET7 Vespa cylinder. Diameter 58mm and original stroke 51mm so close enough for my GP125.

[Henrik Y]

Got a HPI ignition, they had a kit for Suzuki TS50 so I took that flywheel as the cone angle is the same but the stator plate is different so had to measure and take the closest available. It's tight against the inside for the screws and it need's to be spaced out a bit.

The engine case requires some welding to make the cylinder fit. Turned down the cylinder head to get the right height and then added a grove for an o-ring. Filled up the holes around the intake with JB-weld so I could increase the size and shape it.

[Henrik Y]

By this time I've got a tiny little shed on wheels where I have a little Chinese lathe and a work bench so I could do some work during the winter(here in Sweden we get snow and -20°C).

I built up the intake with weld and then bored it to size and it's 32mm inside just as the carburetor. Then I bored the clutch case and made a grove and a top plate to seal it with an o-ring. Made the seat pad and it is "plopp" mounted with studs and cable rubber grommets, I used the same style of mounting for the side covers as well.

And then I made the front fender, now I've got the cheapest Chinese English wheel which helped a bit with smoothing it out but all the shaping is done with the mallet and then chasing small bumps with it as well so the wheel is not some magic tool that spits out perfect parts. I also have a bracket under the fender to help stiffening the fork.

[Henrik Y]

I built the pipe for a little wider power band and at first it got a little high so couldn't use it all before the vibrations got to crazy and I couldn't rev out in 4th gear to get into the power band in 5th, so I lengthened it a little bit and lowered the cylinder so the exhaust got around 189° and it got better. But crank balancing is still to come.

Braced the swingarm, built a cooling shroud for the cylinder, battery holder and silencer. I got a zinc plating kit so I could plate my own parts and freshen up the old. It has to pass MOT so important the get the exhaust sound down as much as possible.

[Henrik Y]

I balanced the crank after the Dragonfly75 calculator and it turned out very well, got rid of the nasty vibrations and I can rev it out so now the power band is between 8-11krpm. I had to fill in the original holes with aluminium and then put hollow steel plugs on the opposite side, not what you normally expect when putting on a slightly heavier piston.

The wider range pipe makes it possible to over rev a bit but a bit less peak so it doesn't quite reach 11krpm in 5th gear and tops just above 150kmh at the moment. Of course it's fun to chase a high top speed but for riding on the twisty country roads it's "just perfect"(in Allen Millyards voice).

As I said in the first post I'm partially paraplegic and 100% paralyzed in the red areas, I can put my feet up and down on the pegs but that's it, and it's hard enough in this crunched position. On more upright bikes I can use pedals with slight modification like enlarged toe heal and such. First I tried with a lever on each side that I just hade to kick forward to shift up on one side and down on the other. But it away to much focus and interfered with my riding position a lot so I scraped that idea and tried a hand shifter instead and it worked out just perfect. Now I can shift in a split second with my chest against the tank not having to look down at my feet and not missing gears 20% of the time.


https://www.youtube.com/watch?v=Fc98mSo8PCs

[Henrik Y]

I also built a hydraulic clutch, took a Hope bicycle brake handle and modified it to maximize the effective stroke with a new piston with different lengths and sealed a hole in the reservoir. Then made my own slave cylinder using a seal from the bicycle brake caliper which turned out to be just the right size. 10mm diameter in the lever and 19,7mm in the slave cylinder. Gives me about 2,5mm travel on the slave cylinder.

The bicycle brake lever is smaller and easier to handle with the rear brake on the handlebar as well. It's a little heavy for 1 finger use but 2 fingers is very comfortable and easy.

And that's my last post for now.

[Flettner]

I had to put a muffler on it.
Tune getting better. 'Siding Gib' throttle works beautifully.

[TZ350]

.
Hi Henrik Y. That is a great Suzuki GP project. I love it and I will dig out the info for you on what was involved in fitting the TS 6 speed gear box to my 5 speed GP/NSR 110cc hybrid. As it will take some digging, please give me a day or two.

[husaberg]

Hello, I'm going to share some pictures of my Suzuki GP build

That's really great thanks for sharing it.

[TZ350]

Tune getting better. 'Siding Gib' throttle works beautifully.

Great to hear that the sliding Gib throttle works very successfully. Another world first for you.

I guess the sliding Gib idea could could also be used to vary the inlet timing at part throttle. Instead of being symmetrical. The throttled down inlet window could be moved about to the timing position where blow back through the inlet is reduced or hopefully even eliminated.

[Flettner]

Great to hear that the sliding Gib throttle works very successfully. Another world first for you.

I guess the sliding Gib idea could could also be used to vary the inlet timing at part throttle. Instead of being symmetrical. The throttled down inlet window could be moved about to the timing position where blow back through the inlet is reduced or hopefully even eliminated.

Thats where the electric throttle would be perfect, but beyond my pay scale at the moment.

[Pursang]

Thats where the electric throttle would be perfect, but beyond my pay scale at the moment.

Neil, you're Priceless!

[speedpro]

I balanced the crank after the Dragonfly75 calculator and it turned out very well, got rid of the nasty vibrations and I can rev it out so now the power band is between 8-11krpm. I had to fill in the original holes with aluminium and then put hollow steel plugs on the opposite side, not what you normally expect when putting on a slightly heavier piston.


I've had a bit of success with rebalancing flywheels with no maths involved. Those alloy slugs would reduce the counterweight which would suit a lighter piston or higher revs. The steel slug with the recess machined out would also reduce the counterweight which also suits a lighter piston or more revs. The increased revs are probably more important to be compensated for in your case hence your modifications whereas the force increase due to a heavier piston less so.

Given that cylinder geometry in the chassis, upright or lying down, and engine mounting rigidity and a few other things affect how it feels, it is always the end result that will guide future tinkering with counterbalance.

[F5 Dave]

Henrik. I've just been looking at Clake products in Auss for dirtbike rear hand brakes. Google them. Very spendy but can go down rabbit hole of assisted light clutch pull and combo rear brakes.

[husaberg]

Henrik. I've just been looking at Clake products in Auss for dirtbike rear hand brakes. Google them. Very spendy but can go down rabbit hole of assisted light clutch pull and combo rear brakes.

gee they have got spendy, pretty sure the original did both off one lever


https://youtu.be/86qN3anUTy8

was this the original?

https://www.clake.com.au/prices/clakelhrb-prolever-standard/

or just like micks
https://www.youtube.com/watch?v=xlXZveDfdd0
https://www.youtube.com/watch?v=FZ48QWS-ZkQ

[F5 Dave]

There's lots of options as they evolve. That Baylis chap seems keen on the version shown for motard.

[ken seeber]

Henrik. I've just been looking at Clake products in Auss for dirtbike rear hand brakes. Google them. Very spendy but can go down rabbit hole of assisted light clutch pull and combo rear brakes.

Another servo type rear brake system is being developed over here in Western Australia. Here are a couple of links:
https://www.facebook.com/brakebutt/
https://motorbikewriter.com/brakebutt-links-front-back-brakes/

Here are a couple of pics of the system fitted to my EXC TPI. We got involved in the early design and making these prototypes. Lots of guys in enduros swear by them. No need to use your right foot. It sort of feels like having power brakes after no assist.

350024350023350022

[Frits Overmars]

I've had a bit of success with rebalancing flywheels with no maths involved. Those alloy slugs would reduce the counterweight which would suit a lighter piston or higher revs. Engine revs won't influence the direction of vibration. They do however influence the vibration frequency, and a certain frequency in combination with a certain vibration direction can cause a resonance in the chassis. The remedy would be to change the vibration direction by altering the balance factor.

[F5 Dave]

Another servo type rear brake system is being developed over here in Western Australia. Here are a couple of links:
https://www.facebook.com/brakebutt/
https://motorbikewriter.com/brakebutt-links-front-back-brakes/

Here are a couple of pics of the system fitted to my EXC TPI. We got involved in the early design and making these prototypes. Lots of guys in enduros swear by them. No need to use your right foot. It sort of feels like having power brakes after no assist.

350024350023350022

That's quite a different approach. Have to think about that.

[wobbly]

Just to add to Frits analysis , the balance programe seems to minimise vibration in total, both x and y relative to the cylinder axis.
But its been well established that any vibration in Y , that is a vertical vector , is way more of an issue with regard to the riders hands and balls.
Thus having the absolute minimum all round may not in fact give the optimum vibration profile that does not excite the frame or rider in the y axis.
Having a low y at the expense of a higher forward/back vector may in fact be felt as way better , disregarding the forces on the mains and case tunnels.

[TZ350]

.
Hi Henrik Y. Thanks for posting your Suzuki GP project. I loved the hand shifter modification your made that makes riding easier for you.

Here are some of the details about our gear box conversions. Our first one was fitting an early 5 speed TS125 box to the GP and then a later 6 speed TS125 box. We wanted to get rid of the big gap between 2nd and 3rd in the GP box and we used TS gear box's because our Bucket racing rules require non competition parts so TM and RM parts are out bounds for us.
.

350026

There is quite a bit of work in fitting an early 5 speed TS box to the GP. We cut of the front part of the GP input shaft and spigoted the TS shaft with a press fit into it and then welded so that the shaft finished up the same length as the original GP shaft. The TS shaft also needed drilling through for the clutch push rod.

Two of the gear selectors need building up on one side each (opposite sides) because the groves in the TS gears are wider than the GP ones. And the third GP selector needed grinding out to fit over the TS gear.

350027

The 6 speed TS gear shafts are about 12mm longer than the 5 speed GP shafts. Which means the cases have to be spaced apart. and a center spacer made.

350029 350028

The center spacer and wider crankcase also means that the big end pin needs to be longer too.
We enjoyed the extra crankcase volume as it gave more room for the pipe to suck a good lung full of fresh mixture from.

The big challenge was relocating the spring loaded selector drum plunger. The indents on the 6 speed drum are indexed from the same start position but in a different place along the drum.

350030

As well as the crankcase spacer we also used a longer (RD400 115mm with 22mm B/E pin) for even more crankcase volume. The spacer under the cylinder sets the exhaust timing to 80 ATDC. And the to of the cylinder was trimmed to get the squish right.

[Henrik Y]

.
Hi Henrik Y. Thanks for posting your Suzuki GP project. I loved the hand shifter modification your made that makes riding easier for you.

Here are some of the details about our gear box conversions....


Thank you!

I had a look around and found an old Suzuki RG 125 for cheap, it looked very much like the TS and GP gearbox so I just bought it so will see how it turns out.

[F5 Dave]

So aside from just running that engine, you will need a long rod and sturdy alloy block to adapt the narrow GP barrel to a wider crankcase.

[TZ350]

.
350038

I had nearly given up hope and was going to use the basic road setup but a gift from the Gods arrived on my desk a couple of days ago.
A genuine Kawasaki factory F81M close ratio gearbox. Thanks Flettner....:wings:
.

[pete376403]

Now you need the F81m ignition rotor instead of the monster that is standard

[Peter1962]

There is also the modification for the bighorn gearbox that klemracing.com is selling : they use a fifth gear from the H1 and a purpose built first gear. http://www.klemmvintage.com/bighorntech.htm
This facebook message gives the price : 209 dollars, that was in 2018 https://www.facebook.com/120511237959379/photos/kawasaki-f5-f8-f9-close-ratio-5th-gearthe-stock-5-speed-transmission-of-the-kawa/2105923856084764/

[TZ350]

.

350054

It is the Benelli's in the pre 72 Post Classic class that I am hoping to chase around with the 250cc Kawasaki.

350055

The ignition system is a DCCDIP2Race Ignitec firing both outputs into a Crain coil and surface gap plug. So basically something like an arc welder getting the Methanol burning. I need 14 Volts and 80 Watts for this system.

350056

The generator is a modified light weight Chinese after market unit that I re wind for greater output. Hopefully I can get 80Watts out of this one. 80 Watts is not needed all the time as demand is RPM dependent. There is no battery in the system. Only two (4amp) Voltage rectifier regulators and 56000uF 50V capacitors. A simple push and it all lights up. We have similar systems on some of our other bikes so have complete confidence in it.

Another benefit of the Ignitec ignition is that it can pulse a power jet. The Ignitec works by grounding the power jet solenoid coil. So all I need is a temperature sensor on the head that supply's power to the solenoid when the engine gets hot and the power jet dumps extra Methanol into the carb to cool the engine. That way I get the start and first lap or so with the engine running clean. Then when its warmed up the extra Meth will keep it cooled and reliable for the rest of the race.

[Peter1962]

.

350054

It is the Benelli's in the pre 72 Post Classic class that I am hoping to chase around with the 250cc Kawasaki.

350055

The ignition system is a DCCDIP2Race Ignitec firing both outputs into a Crain coil and surface gap plug. So basically something like an arc welder to get the Methanol burning. I need 14 Volts for this system.

350056

The generator is a modified light weight Chinese after market unit that I re wind for greater output. Hopefully I can get 80Watts out of this one. 80 Watts is not needed all the time as demand decreases at lower RPM. There is no battery in this system. Only two (4amp) Voltage regulators and 56000uF 50V capacitors. A simple push and it all lights up. We have similar systems on some of our other bikes so have complete confidence in it.


Wouldn't the suggested solution by klemmvintage not be easier ? Buy a cheap KX 250 +2000 ignition.

[TZ350]

Wouldn't the suggested solution by klemmvintage not be easier ? Buy a cheap KX 250 +2000 ignition.

Easier maybe, but it wouldn't have the programable features of the Ignitec or the fire power. One of the other things I want to do is use the Ignitecs power valve servo feature to open/close a bleed on the side of the dwell section of the expansion chamber.

The object here is to vary the working pressure inside the expansion chamber. Earlier experiments on the dyno showed that the sick area in the torque curve just before the engine came on the pipe could be considerably cleaned up by dropping the pressure in the pipe. it became obvious on the dyno that the pipe pressure only had to be at its normal value at peak torque. Every where else it was better to have lower pipe pressure than you got with a fixed stinger optimized for maximum power.

I am also interested to see if dropping the pipe's working pressure after max power helps with reducing over rev detonation. And may be it will also help extend over rev itself.



320042

Some time ago Frits posted an idea on how to reduce over run deto and cylinder overheating by lowering the pipes internal operating pressure in the over rev zone.

320043

I made my own version of a pipe pressure blead from a model aero engine carburettor body and gave it a try.

Unfortunately it was only hand controlled and I could not get an overrun picture but it did show some interesting pre peak power results.

320044

Blue is with it closed and the pipe at its normal internal pressure and red is with it open and some of the pressure bleed off. A surprisingly useful extra 500 rpm at the lower end and another surprise was that it was not that noisy.

I am sure that once it can be automatically controlled by the IgniTech, say closing at 10,500 rpm and opening again at 12,500 it would add some usefull spread and reduce over run deto and maybe even extend the over rev a bit.

500rpm at the bottom plus another 500 at the top and a reduction in cylinder overheating would be very handy in anyone's books.

So a pipe pressure bleeder looks like a useful option if you are looking for ways to extend the power spread and avoid (reduce) over heating from hot exhaust gases back flowing down the transfer ducts during over rev when blowdown is time limited and the internal pipe pressure is high.

[speedpro]

I seem to recall conversations with Pete Sale where he was complaining about detonation in his 400 2T when he closed the throttle. Possibly something to do with an "unclean" mixture and chemistry with the methanol.

[TZ350]

I seem to recall conversations with Pete Sale where he was complaining about detonation in his 400 2T when he closed the throttle. Possibly something to do with an "unclean" mixture and chemistry with the methanol.

Yes. If you have maximum spark timing for drive out of corners. A 2T needs to retard the spark when the throttle is (partly) closed because there is reduced cylinder purging and pipe suction on part throttle and there is more hot dirty contaminated mixture left in the cylinder.

Jamathi talks about it here:- https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner/page2000 about half way down the page.

[TZ350]

.

350057350058350059

Flettner's bike. Worlds first, mk2 TPI and Sliding Gib throttle / variable rotary valve timing all in one.

[TZ350]

.

350060

Open heart surgery replacing the standard F5 gear cluster with the new (to me) F81M close ratio cluster.

.

[F5 Dave]

I seem to recall conversations with Pete Sale where he was complaining about detonation in his 400 2T when he closed the throttle. Possibly something to do with an "unclean" mixture and chemistry with the methanol.

He told me that initially they had a wasted spark ignition that methanol wasn't keen on.

[F5 Dave]

.

350060

Open heart surgery replacing the standard F5 gear cluster with the new (to me) F81M close ratio cluster.

.

I might need to change my KB name now that F5 means something different :bleh:

[TZ350]

.

350061

Engine back together with the highly coveted F81M gear cluster.

350062

Massive spark injector hiding under the tail of the tank.

[Flettner]

I might need to change my KB name now that F5 means something different :bleh:

All the more reason to keep the name F5, I would have thought.

[pete376403]

Did you read the comments on the Klemm site about matching the cases to avoid air leaks. He says the factory didnt machine the cases as a pair and can be quite different at the cylinder base. Wish i had known that sort of thing when I had the F9 - it was great when it was going but had a number of failures (which Laurie Summers wouldn't cover under warranty, something about riding it off road was considered user abuse)

[F5 Dave]

I love the tank, but did you borrow your granddaughters My-first-cellphone to take the pictures?

[TZ350]

I love the tank, but did you borrow your granddaughters My-first-cellphone to take the pictures?

I am not sure what happens, they look alright and properly orientated on my computer but KB posts them in odd ways. I have given up fighting with it.

[TZ350]

Did you read the comments on the Klemm site about matching the cases to avoid air leaks. He says the factory didnt machine the cases as a pair and can be quite different at the cylinder base. Wish i had known that sort of thing when I had the F9

Yes, milled the crankcase cylinder base flat across its surface and square to the main bearings as part of the process. Top of the cylinder is milled 3mm to move the transfers up and the head is grooved for a 2mm Viton "O" ring to serve as a head gasket, 0.8mm squish. Ex opens 81 ATDC, 34mm carb, Inlet opens 155 BTDC and Closes 90 ATDC. Ignition self generating CDI from 12-14 Volts DC and fully programmable.

LOL I worked for Laurie Summers Mt Eden branch sweeping the floors after school. There was a F81M on the show room floor. I loved it. His Mt Eden shop was just over the road from Russels and I also spent time hanging around Whites in Newmarket. Later I worked at the engine re-conditioners down the drive next to Laurie's shop. Crosby and Eric worked at Laurie's Onehunga shop.

[husaberg]

I love the tank, but did you borrow your granddaughters My-first-cellphone to take the pictures?
.......................
350063

[Frits Overmars]

350064

Open heart surgery replacing the standard F5 gear cluster with the new (to me) F81M close ratio cluster.That piston skirt surprises me. It forces you to either use a narrow, high exhaust port (not so good for low-down power) or to accept a lot of transfer to exhaust short-circuiting, dumping unused fresh mixture into the pipe at such an early stage that it will have moved too far downstream to be shoved back by the exhaust return pulse.
On the other hand, it will lower the EGT, helping low-down power :whistle:

[TZ350]

350064
That piston skirt surprises me. It forces you to either use a narrow, high exhaust port (not so good for low-down power) or to accept a lot of transfer to exhaust short-circuiting,

The cylinder dictates a single exhaust port. 72% bore width is the most I dare. To get the desired STA I have to open the Ex port of 81 ATDC. The skirt covers the port with 2mm spare each side. I might be missing something, I will have another look. Thanks.

[Frits Overmars]

The cylinder dictates a single exhaust port. 72% bore width is the most I dare. To get the desired STA I have to open the Ex port of 81 ATDC. The skirt covers the port with 2mm spare each side. I might be missing something, I will have another look. Thanks.If you are forced to use to a single exhaust port, you haven't missed anything. The wider you make any port, the bigger the radii in the corners need to be in order to keep the piston ring alive, and those radii will reduce the port width at the top, where the area counts the most because it's open for the longest time.
A port width of about 70% of the cylinder bore will give you the maximum blowdown angle.area, so that is the optimum port width.

[andreas]

From your pics it looks like it only need some welding outside the exhaust- and Shazam.

[TZ350]

If you are forced to use a single exhaust port, you haven't missed anything. A port width of about 70% of the cylinder bore will give you the maximum blowdown angle.area, so that is the optimum port width.


From your pics it looks like it only needs some welding outside the exhaust- and Shazam.

I have a spare cylinder that needs re boring. After the bike is running and I get bored I was going to do something like Andreas suggests. The plan is to mill a 12mm wide section between two fins parallel to each side of the exhaust duct. Then cap them with a small section of 12mm plate in such a way it leaves room for an axillary exhaust duct underneath. Then at each end of the channel drill through to the cylinder and main Ex duct. Viola, a triple exhaust port.

For me, the main motivation for the triple exhaust port in the spare cylinder is the ability to have the correct STA and reduce the height of the exhaust to get closer to the optimum resonant exhaust timing of 190 - 194 duration. If I get really clever I could have the 12mm cap pieces swing in such a way they can block the axillary ports. A power valve servo could be used to pull them in/out as RPM dictates.

I have to be a little careful as the Pre 72 Post Classic racing class here in New Zealand dictates that the engine must look original on the outside. They must look like they did when actively raced pre 72. Onus of proof is on the rider and I don't have a lot of photos of triple exhaust port F81M's.

350066

Not my bike or Grand Daughter but I would be happy if they both were.

[F5 Dave]

I'd suggest photoshop, but I don't think it's your strong point. Maybe you could ask your granddaughter :innocent:. But dont use her phone; its probably got a better camera and in this instance, blurry might be an advantage.
Sure Kawasaki had a special Indonesian model with the triple port, as 3 is the national lucky number and 1 is considered evil.

[Flettner]

Did you read the comments on the Klemm site about matching the cases to avoid air leaks. He says the factory didnt machine the cases as a pair and can be quite different at the cylinder base. Wish i had known that sort of thing when I had the F9 - it was great when it was going but had a number of failures (which Laurie Summers wouldn't cover under warranty, something about riding it off road was considered user abuse)

Kawasaki were F$%ckers, their F5 / F9 was nearly a good engine. The rest of the running gear was years out of date.
Silly problems like no squish, three ring heavy piston, clutch too small, a stupid LH / RH crank gear attachment that always eventually undid and poked a hole in the case.
The heavy piston would crack and drop a piece down into the rotary disc valve. Short reach plugs that would eventually strip and blow a plug out. And many more small but annoying issues. Clearly Im still bitter after all these years. ��

Gearbox was good though.

They nearly had something good and just squandered it.
If Kawasaki ring me back now Ive sorted all their problems for them, they can go back into F9 production again. ��

[Flettner]

I dont know why the emojis dont show up, but Im sure you get the picture.

[Flettner]

Now you have me started, on a good evening, planets aligned, paid your dues, the power was outragous. Especially with the original Kawasaki 'hot kit', king of the heap.

[pete376403]

The heavy piston would crack and drop a piece down into the rotary disc valve.

I think that is what my one did a couple of times, r/v would be shredded - i thought it was happening the other way, the disk breaking and the shrapnel taking out the rest of the engine. The magneto rotor would shear the woodruff key occasionally too. Finally fixed that by lapping the rotor to the crank. But given all its faults I'd still like another one.

[Flettner]

The Bighorn was supposed to be good for 44 HP with the hot kit.
At 6000 about 15HP
7000 it got excited
8500 it was anyones guess as to where it would all end up. Ditch? ambulance? Or win, control was never a strong point of the Kawasaki Bighorn.

[Flettner]

A modern Bighorn

[speedpro]

You can see the resemblance

[Flettner]

You can see the resemblance

Haha I can.
https://youtube.com/shorts/CLn4tsz8M1s?feature=share

[_____]

One question for Jan and Frits:

When I go through the history of the Aprilia Cylinders. I find that in the beginning, with Rotax 128, 129 and even the APC the bottom edge of the boostport is well below the BDC. Roughly 5mm.
Looking into newer cylinders like the APE and APF, I find that the bottom edge sits at about 1.5mm lower than BDC.


Why is the lower edge dropped anyway? And why was it raised in the development process?

Thanks a lot from germany
Chris

[Frits Overmars]

One question for Jan and Frits:
When I go through the history of the Aprilia Cylinders I find that in the beginning, with Rotax 128, 129 and even the APC the bottom edge of the boostport is well below the BDC. Roughly 5mm. Looking into newer cylinders like the APE and APF, I find that the bottom edge sits at about 1.5mm lower than BDC. Why is the lower edge dropped anyway? And why was it raised in the development process?
Thanks a lot from germany
ChrisWhen I first held a water-cooled 125 cc Rotax cylinder in my hands, in 1977 or 1978, it already had the piston ring gap running over the middle of the C-transfer, which was then 22mm wide. It never gave any problems. The low bottom edge of the C-port ensured that the ring gap did not have to run over it at BDC, which made sense to me.

In the later Aprilia cylinders the C-port width was reduced from 22 mm to 15 mm to allow for wider B-transfers, and Jan noticed that raising the C-port bottom improved flow without causing any ring problems. I don't think a combination of the original 22 mm Rotax port width and the raised Aprilia port bottom was ever tested.

Gestatte mir eine Gegenfrage Chris: warum verwendest Du fünf Unterstriche als Spitznamen? "Chris" ist doch gar nicht so schlecht, oder?
(for anyone who hasn't been punished with German lessons: consider this a great opportunity to practice with Google Translate :msn-wink:)

[_____]

Thank you Frits,

that was helpful!

About my nickname: That was what I came up with. No fancy reason behind it :-)

Regards
Chris



When I first held a water-cooled 125 cc Rotax cylinder in my hands, in 1977 or 1978, it already had the piston ring gap running over the middle of the C-transfer, which was then 22mm wide. It never gave any problems. The low bottom edge of the C-port ensured that the ring gap did not have to run over it at BDC, which made sense to me.

In the later Aprilia cylinders the C-port width was reduced from 22 mm to 15 mm to allow for wider B-transfers, and Jan noticed that raising theC- port bottom improved flow without causing any ring problems. I don't think a combination of the original 22 mm Rotax port width and the raised Aprilia port bottom was ever tested.

Gestatte mir eine Gegenfrage Chris: warum verwendest Du fünf Unterstriche als Spitznamen? "Chris" ist doch gar nicht so schlecht, oder?
(for anyone who hasn't been punished with German lessons: consider this a great opportunity to practice with Google Translate :msn-wink:)

[wobbly]

I tested lowering the C port floor , thinking there was a good reason to do it , as I had also seen it done by Rotax and various 100cc kart engine manufacturers.
Sadly the flow bench said " nah " and so did the dyno.
My thinking afterwards was that without the last part of the inner wall directing the flow , it simply attached to the vertical piston face , thus screwing up the directional control of the roof trying to keep
the column at 50* or whatever.

[Condyn]

350073

It may be hard to tell in this photo, but the B ports on old 4 port Yamaha piston port snowmobile cylinders drop well below bdc. The B axial angles are roughly 45 degrees. I have never been able to wrap my head around why you would want collision on the piston sending the B column into a turbulent tornado headed for the moon.

[TZ350]

.
Wob did tell me but I can't re locate his post.

350076

Wob or anyone with experience with setting up the EngMod2T temperature file for Methanol. I would love some pointers on what temperatures to plug in.

[wobbly]

160*C bottom of powerband 225*C peak for the pipe , but the Ex Port duct will be much cooler in an Aircooled so that will need dropping as well.
I havnt done an Aircooled on Meth in EngMod so cant show any experience.

[TZ350]

160*C bottom of powerband 225*C peak for the pipe , but the Ex Port duct will be much cooler in an Aircooled so that will need dropping as well.

Thanks Wob. Even though the F81M is air cooled I had used the default water cooled temperature settings in the hope they would be closer to a Meth air cooled engine. I will plug your numbers in and experiment a bit. Thanks again.

[philou]

curious form

350083

[Frits Overmars]

curious form
350083Well spotted Philou. You might even call it cheating :Oi:

[philou]

I am curious to know the result behind this form ?

[jonny quest]

Well spotted Philou. You might even call it cheating :Oi:

Not familiar with this model bike. Center bodies look to be removed drastically shortening pipe. Why do you mention this as "cheating " ?

[wobbly]

There has only been one specific engine application where having no dwell section created any usefull power - and it sure wasnt a Honda NX
Any other use of this design is a complete fuckup and will never make any power - end of story.
I wouldnt take those pipes if you gave them to me,

[Frits Overmars]

Not familiar with this model bike. Center bodies look to be removed drastically shortening pipe. Why do you mention this as "cheating " ?How would you call it when someone offers 'Honda NX5 pipes' that will be completely worthless on a Honda NX5 (or on any other bike for that matter) ?

[SwePatrick]

No good camera angle, but you can hear the sound, last pull was out of juice in the battery for ignitech(even though i said something different)
And still it produced 83whp in that pull, might have been 84 if it didn´t get low voltage.
However, the pipes are designed to be run with nitrous oxide(not activated in these pulls), thereby the 'low rpm', but i recon 83whp is quite good at only 10599rpm ;)
And when i was about to show you the graphs, i forgot to klick to show the power, it only showed exhausttemps, my bad, but you can see the numbers.


https://youtu.be/RNQuoH-zg_w

[jonny quest]

How would you call it when someone offers 'Honda NX5 pipes' that will be completely worthless on a Honda NX5 (or on any other bike for that matter) ?

I see what you mean. The seller is "cheating " a buyer out of their hard earned money.

And yes, I knew at first glance those pipes were junk. And after Google told me what an NX5 was, I really knew these were worthless. Cheating, how I perceived it at first, was bending some racing rule by modifying the pipes that way. I was curious how that modification could benefit anything.... because I was "almost" positive it couldn't.

[wobbly]

SwePatrick , that has to be one of the nicest jetted engines I have ever heard when blipping the throttle , wow.
But as I am always slinging shit at riders who come into the pit and I hit max recall , and it shows 14980 , when the red dash warning light comes on at 14600, you cant tell me you couldnt see
that headlight size white warning come on ( just joking ).

[SwePatrick]

SwePatrick , that has to be one of the nicest jetted engines I have ever heard when blipping the throttle , wow.
But as I am always slinging shit at riders who come into the pit and I hit max recall , and it shows 14980 , when the red dash warning light comes on at 14600, you cant tell me you couldnt see
that headlight size white warning come on ( just joking ).

Thanks =)

I pulled all the way to revlimiter, but shiftlight was setup early as the driver i had actually didn´t see it ;)
If you look real hard when blipping the throttle on the screen, the rpm gauge is almost instant at revlimiter.
The gauge on the bike is way to slow to keep up ;)

Setup on this bike is really simple acutally, an early tzr250 engine (1kt)
With a spacerplate so it accepts the latest oem tzr250 cylinders(3xv)
Ofcourse they are ported, 194/188/130/134/134 are the timings.
B-ports are opened up quite a lot as the 'runners' do accept this as they are way to big oem.
Modified the combustionchambers with RSA in mind.
Woessner YZ125 pistons
The exhaust 'runner' is quite small also, only 34mm in diam.
The auxports are opened up as much as the piston allows(188 duration)
YPVS is blocked fully open, powercurve is above oem all the way from ~7500-12000rpm
V-force 4 reeds, but with polini 0.4 petals(oem can't take ethanol/methanol)
Keihin PWK 39mm carburetors(cheap as shit in Sweden due to they are mounted oem on snowmobiles)
Stainless steel pipes of own design(in MotaX)
Ignitech ignition
Modified clutch as oem didn´t take the power, with 8 springs instead of 4, and carbon discs from yzf250f.

[katinas]

Cylinder from first street NSR 250 MC16. Interesting, C floor is 3.5mm higher than BDC.

[katinas]

Tests with a quick removable exhaust insert, that mimic Jan’s idea of a higher exhaust floor. Of course there is some leakage through insert sides, so its not very accurate replication. Just general feelings of engine reaction.
Comparisons with and without insert on Honda RS cylinder, without any other adjustments.


1. Insert height 11mm, imitate exhaust floor height nearly at the level of the transfers top.
From 0 to 8000 rpm much better, but worse at top end.

2. Insert height 7.5mm, midrange and top similar to std, but top end revs increased by 300-400 rpm. This repeated every time after insert was installed.
Without the insert, only too retarded ignition add similar rpms, but power started to drop.
Changes done directly on the road in 5min.

[TZ350]

.

Now you need the F81m ignition rotor instead of the monster that is standard

350093

I hear what you are saying. I will be using the smaller rotor from a Chinese after market CDI unit. Mostly so I can re wind it for 14 Volts @ 75 Watts. The bigger rotor is from the Kawasaki F5/9 250 or maybe it is Suzuki TS250. Anyway a big mass saving over std 250 rotors.

[TZ350]

.

2Stroke Stuffing makes progress on constructing a dyno to test the supercharged 50cc engine:- https://youtu.be/9EbPmGjWEk0

.

[jonny quest]

https://youtu.be/zCoBtMT7_Ds

[TZ350]

https://youtu.be/zCoBtMT7_Ds

That is very clever. 10 cylinders. Roots type blowers for scavenging.

[lodgernz]

This is interesting...
https://www.trademe.co.nz/a/motors/motorbikes/parts-for-sale/engine-components/listing/3342399651?bof=mTic2mSq&fbclid=IwAR1yAUa_4rASiNzJ8tmVflfZWgRrVKSBOXA5gP9R9 wB3GDQZaG6vOju3otE

[vro46i]

[QUOTE=SwePatrick;1131193013]Thanks =)


Keihin PWK 39mm carburetors(cheap as shit in Sweden due to they are mounted oem on snowmobiles)

Hi there, I am after a pair of for my NSR 300, would you be so kind to point me in the direction of where online, to look for the aforementioned carbs?
Thanks

[husaberg]

This is interesting...
https://www.trademe.co.nz/a/motors/motorbikes/parts-for-sale/engine-components/listing/3342399651?bof=mTic2mSq&fbclid=IwAR1yAUa_4rASiNzJ8tmVflfZWgRrVKSBOXA5gP9R9 wB3GDQZaG6vOju3otE

i seen something the other day about them going into recievership
I think they have between 4 and ten powerplants.

[lohring]

Model engine radial builders took a simpler path.

https://www.youtube.com/watch?v=j4AM6Zz44gE&t=385s

Lohring Miller

[TZ350]

Model engine radial builders took a simpler path.

https://www.youtube.com/watch?v=j4AM6Zz44gE&t=385s

Lohring Miller

I followed Lohring's link. All sorts of model engines came up. https://youtu.be/h26rtBJsS-8 this one a 4S, is a little hard to start but sounds great.

[vro46i]

Good day to all,

First-time writer, long-time reader. After much encouragement, I am bringing my "plate" to the dinner party.
Ironically this is also the first 2 stroke engine build that I am undertaking after owning a fleet of NSRs for nearly a decade and a half.

The engine I am basing the build on is a 1992 RGV125, with the aim of modifying/ assembling a 110cc engine that is reliable and competitive in the F4 bucket class,


The engine I bought was without the following components:
flywheel, stator, stator cover, Ignition pick up, oil pump, and piston. It is not the end of the world as I was able to locate parts on Ebay, but under the current Covid effect climate, postage is a killer.


RGV Crankcase tear down and configure the engine architecture.

I stripped the crankcase right down to bare casing to clean, inspect, deburr, and measure. At least I will have some quantitative figures to ask pertinent questions.

The bore and stroke specification from that particular model of RGV125 is 56mm and 50mm respectively.
To fit with the F4 rules, I will have to decrease the CC down to 110, I was advised that due to the overbore dimensions of the OEM cylinder bore the sensible way forward is to graft a 54mm diameter NSR 250 cylinder onto the RGV crankcase. This will bring the bore stroke ratio closer to 1:1. That is achievable as I have a few of those as per my initial comment of hoarding NSR parts. hahaha.

A bore reduction was considered, as the RGV cylinder has a steel sleeve as standard, but then the fun of getting the new steel sleeve manufactured, installed, port matched and lastly having to find the right piston.

Further cc reduction will be achieved by de-stroking the crank from 50mm to 48.3mm.

NSR barrell to RGV crankcase interface

Further disassembly allowed me to mock up the cylinder to the crankcase. What I discovered was that the bolt/ stud pitch of the pair of studs on the intake side is narrower than the RGV by half a hole each. Where the exhaust pitch is marginally better at 1/3 of the hole.

Hole misalignment issue aside there is the case of matching up the water jacket holes on the exhaust side, to ensure that there is enough casting to provide the necessary sealing surface.
Moving around to the intake and transfer ports, the RGV crankcase ports are significantly larger than what is present on the NSR cylinder. The intention here is to port match both cylinder barrel to the crankcase to allow for less disruptive flow transfer.

The plan for retrofitting the cylinder onto the crankcase will involve manufacturing the stud blanks out of 2024 or 6061 and winding them into the holes with Loctite 638. Once the Loctite has curred, the crankcase to cylinder mounting face will be milled to regain a flat surface.

Both the crankcase opening and the NSR barrel are then "clocked" to find the relative centres of the bore, thus allowing for alignment prior to drilling the NSR barrel mounting pattern.

In the scenario where the crankcase opening is significantly larger than the cylinder barrels are there any pitfalls I should be cognizant of before the carbide burr gets deployed? The mixture flow from the RGV crankcase into the NSR cylinder barrel converges via this significant change in cross-section, is this acceptable? what is preferred?


I have a lot of questions rattling around in my head which I am keen to ask but I will spread them out in a later post.

As this is my first post, I thank you for taking the time to read this, guidance and advice are greatly received and appreciated in this build.

regards

[F5 Dave]

This is interesting...
https://www.trademe.co.nz/a/motors/motorbikes/parts-for-sale/engine-components/listing/3342399651?bof=mTic2mSq&fbclid=IwAR1yAUa_4rASiNzJ8tmVflfZWgRrVKSBOXA5gP9R9 wB3GDQZaG6vOju3otE
Chocolate fish for first one of those in a scooter :crazy::banana:

[Grumph]

Chocolate fish for first one of those in a scooter :crazy::banana:

If I was 20 years younger I'd be scraping up the money to bid. I've posted pics of that stuff on here previously - obtained from one of the development team.
By the standards of most on here it was never developed. They just had to achieve reliability at a pretty low redline to meet aviation standards.

I really don't know what application it could be used in - two litre sports cars ? A scooter is probably as good as anything.

[TZ350]

Good day to all,

First-time writer, long-time reader. After much encouragement, I am bringing my "plate" to the dinner party.
Ironically this is also the first 2 stroke engine build that I am undertaking after owning a fleet of NSRs for nearly a decade and a half.

The engine I am basing the build on is a 1992 RGV125, with the aim of modifying/ assembling a 110cc engine that is reliable and competitive in the F4 bucket class,



Welcome vro46i. Great to see another 110cc F4 Bucket build on its way. :2thumbsup I am looking forward to following your progress.

[F5 Dave]

If I was 20 years younger I'd be scraping up the money to bid. I've posted pics of that stuff on here previously - obtained from one of the development team.
By the standards of most on here it was never developed. They just had to achieve reliability at a pretty low redline to meet aviation standards.

I really don't know what application it could be used in - two litre sports cars ? A scooter is probably as good as anything.
Dirtbike to go with genetic material. 200hp and knobblies. :banana:

[F5 Dave]

I followed Lohring's link. All sorts of model engines came up. https://youtu.be/h26rtBJsS-8 this one a 4S, is a little hard to start but sounds great.
Jesus haven't they seen that episode of Wings where the pilot doesn't set the advance right and the propeller spiny guy gets his fingers all cut off?

[andreas]

Good day to all,

First-time writer, long-time reader. After much encouragement, I am bringing my "plate" to the dinner party.
Ironically this is also the first 2 stroke engine build that I am undertaking after owning a fleet of NSRs for nearly a decade and a half.

The engine I am basing the build on is a 1992 RGV125, with the aim of modifying/ assembling a 110cc engine that is reliable and competitive in the F4 bucket class,


The engine I bought was without the following components:
flywheel, stator, stator cover, Ignition pick up, oil pump, and piston. It is not the end of the world as I was able to locate parts on Ebay, but under the current Covid effect climate, postage is a killer.


RGV Crankcase tear down and configure the engine architecture.

I stripped the crankcase right down to bare casing to clean, inspect, deburr, and measure. At least I will have some quantitative figures to ask pertinent questions.

The bore and stroke specification from that particular model of RGV125 is 56mm and 50mm respectively.
To fit with the F4 rules, I will have to decrease the CC down to 110, I was advised that due to the overbore dimensions of the OEM cylinder bore the sensible way forward is to graft a 54mm diameter NSR 250 cylinder onto the RGV crankcase. This will bring the bore stroke ratio closer to 1:1. That is achievable as I have a few of those as per my initial comment of hoarding NSR parts. hahaha.

A bore reduction was considered, as the RGV cylinder has a steel sleeve as standard, but then the fun of getting the new steel sleeve manufactured, installed, port matched and lastly having to find the right piston.

Further cc reduction will be achieved by de-stroking the crank from 50mm to 48.3mm.

NSR barrell to RGV crankcase interface

Further disassembly allowed me to mock up the cylinder to the crankcase. What I discovered was that the bolt/ stud pitch of the pair of studs on the intake side is narrower than the RGV by half a hole each. Where the exhaust pitch is marginally better at 1/3 of the hole.

Hole misalignment issue aside there is the case of matching up the water jacket holes on the exhaust side, to ensure that there is enough casting to provide the necessary sealing surface.
Moving around to the intake and transfer ports, the RGV crankcase ports are significantly larger than what is present on the NSR cylinder. The intention here is to port match both cylinder barrel to the crankcase to allow for less disruptive flow transfer.

The plan for retrofitting the cylinder onto the crankcase will involve manufacturing the stud blanks out of 2024 or 6061 and winding them into the holes with Loctite 638. Once the Loctite has curred, the crankcase to cylinder mounting face will be milled to regain a flat surface.

Both the crankcase opening and the NSR barrel are then "clocked" to find the relative centres of the bore, thus allowing for alignment prior to drilling the NSR barrel mounting pattern.

In the scenario where the crankcase opening is significantly larger than the cylinder barrels are there any pitfalls I should be cognizant of before the carbide burr gets deployed? The mixture flow from the RGV crankcase into the NSR cylinder barrel converges via this significant change in cross-section, is this acceptable? what is preferred?


I have a lot of questions rattling around in my head which I am keen to ask but I will spread them out in a later post.

As this is my first post, I thank you for taking the time to read this, guidance and advice are greatly received and appreciated in this build.

regards

Once the hardware situation is done with, to portmatch the case to the cylinder-usually there isn't much material to grind away from the cylinder, and you want to follow up all the way. You may need to fill the cases instead, or both.

[vro46i]

Once the hardware situation is done with, to portmatch the case to the cylinder-usually there isn't much material to grind away from the cylinder, and you want to follow up all the way. You may need to fill the cases instead, or both.

Hi Andreas,

It would be easier to explain if I can show images of the port mismatch between the RGV crankcase and the NSR barrel. I rechecked the mismatch again with another NSR cylinder and found that this cylinder barrel has another pair of ports flanking the original intake port opening. The cylinder I picked off the pile must be an earlier version.
Right then it will definitely require a reassessment once I get the hardware back then it would present a definitive situation on which to base my discussion.

[vro46i]

Hi all,

Can I have recommendations on where to send my NSR cylinders for Nicasil replating?

Nationally, I have NZ Cylinders in Ashburton, this is the only company I am aware of that is providing the plating service.

Internationally, in the US there is Millenium Technology and in the UK there are a couple, which names skip my mind at the moment.

Are there any reputable companies in Australia?

Given the current situation with freight worldwide being extensively delayed, (working through the pain of getting a set of forks in from Austin, Texas)
I would prefer to engage services in the Asia Pacific region.

I have heard mixed reviews about the Nicasil plating from NZ cylinders, can I get a consensus/ comments/ experience about their service and product?
I am happy to invest in the local economy provided the product/ service is consistent with the cost.

[wobbly]

NZ Cylinders plating is a licenced setup from Langcourt in UK , so the coating is well proven.
The issue is getting detail finishing - to the point I have told them not to touch anything , I will do it all myself.
You grind the ports and put on any required chamfers ( not needed at all on transfers anyway ) before the replating is done.
In fact the best way is to get them to take off the chrome and return it to you before plating.

[speedpro]

I've had work done by NZ Cylinders but not plating a cylinder. They were great to deal with and did a great job

[Flettner]

I fly on cylinders plated by NZ Cylinders, totaly trust them.

[vro46i]

NZ Cylinders plating is a licenced setup from Langcourt in UK , so the coating is well proven.
The issue is getting detail finishing - to the point I have told them not to touch anything , I will do it all myself.
You grind the ports and put on any required chamfers ( not needed at all on transfers anyway ) before the replating is done.
In fact the best way is to get them to take off the chrome and return it to you before plating.

Hi Wobbly,

Yes, there will be detailed work required along with a repair to the exhaust bridge. I would like to copy the port shape and timing from an NX4 cylinder. Langcourts! that was the name of the UK firm that I had forgotten.

Thanks for the advice, I will proceed as recommended.

[Tim Ey]

Langcourt Coating is superb. Also while honing, they do a proper job.
But I would recommend to engrave "DO NOT GRIND THE PORTS" on the cylinder. Otherwise it might be that they chamfer your cylinder anyway.

[TZ350]

I would like to copy the port shape and timing from an NX4 cylinder.

Just copying the port shape, it is not as simple as that. A NSR and NX4 are both 54mm stroke x 54mm bore.

A short stroke NSR cylinders exhaust port with a 48,3mm stroke will be able to have the same timing in crankshaft degrees as a NX4 cylinder but the shape of the exhaust will have a lower top edge and appear to be smaller. But when you calculate out the crankshaft Angle (degrees) and Area you can have the same STA (specific time area) as an NX4. STA is everything.

A short stroke NSR and normal stroke NX4 cylinders exhaust ports, although they may have the same STA, they wont look the same. The shapes will be different.

Something we did with our best short stroke NSR cylinder but we have not totally confirmed it by back to back tests. Posted as, just something to think about. The wider NSR exhaust bridge can have the sides rounded so that it flows much better while retaining its original strength with the narrower NX4 like ring support. The top edges and sides in the exhaust ports blow down area may also be rounded to improve flow out of the cylinder during the blow down period.

With the short stroke 110cc NSR's. We found we had to trim something off the top of the cylinders to get the squish right. Then we found if it was taken from the bottom of the cylinder we could re angle the top of the transfers for a more up swept angle on the transfer ports. See the leaning tower of Pizza principle and transfer port theory:- https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner/page2000

[TZ350]

.

<yt-formatted-string force-default-style="" class="style-scope ytd-video-primary-info-renderer" style="word-break: break-word;">2Stroke Stuffing. God HATES Two Strokes? If not, then why!? </yt-formatted-string>Was so close to getting that dyno ready, then... https://youtu.be/ZwsWTBnDyRU

[philou]

nikasil at Monardi in Italy. hardness and quality of finish

http://www.monardiromanosnc.com/

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[wobbly]

This is what I am saying about having the plater do the finishing.Those transfer chamfers are huge ,absolutely no point as they loose power , and why do you need them .
Its impossible for the ring to bulge out into a transfer port . Only the boost port top and bottom ,needs a small chamfer to help guide the ring ends into the groove.

[vro46i]

This is what I am saying about having the plater do the finishing.Those transfer chamfers are huge ,absolutely no point as they loose power , and why do you need them .
Its impossible for the ring to bulge out into a transfer port . Only the boost port top and bottom ,needs a small chamfer to help guide the ring ends into the groove.

Wobbly, further question regarding your comment regarding the large radius in the pictures provided by Philou. By maintaining a sharp (ish) edge, is the aim of the passing piston ring(s) acting as a guillotine and positively cut the mixture and creates and linear and positive port seal?

Apologies if this is a silly question, I am wanting to understand the concept from a first-principles perspective.

Thanks

[Vannik]

Wobbly, further question regarding your comment regarding the large radius in the pictures provided by Philou.

I am not Wobbly but my understanding is that the radius causes attachment of the flow and diverts it from the direction it is meant to go. Scavenging is not working as designed with the flow on the edge of the scavenging streams sort of fanning out and mixing with the burnt gas and there a bigger chance of short circuiting.

[philou]

the wide chamfers are not good as they function as a funnel allowing the burnt gas to enter the transfers.

for road engines, the nikasyl professionals do not take any risks and make large chamfers to guarantee a certain reliability

[wobbly]

Neels is right, with a chamfer on a transfer port roof or floor the flow stays attached to the surface and tries to " go around the corner ".Thus the exiting column of mixture looses its coherent shape
and fans out with lots of turbulent eddies , thus ruining the scavenging pattern , with random flow in the wrong places.
The sharp edge corner only needs to be broken with a cotton mop , and this has no effect on ring life at all.

The worst case of this is effect shown when putting a radius on the piston edge.
At the boost port , that is angled up sharply , the flow attaches to the piston radius , and pulls down the boost flow directly at the Exhaust on the opposite side.
I had a flash of inspiration the other day when I saw a picture on here of a boost port with the floor up away from BDC - keeping the flow away from that piston radius..
This is probably easyer than making a piston radius start and stop before the boost port , and then having to grind the port timing correction as well.

[lodgernz]

The sharp edge corner only needs to be broken with a cotton mop , and this has no effect on ring life at all.


Wobbly, I've not encountered a cotton mop before. Can you explain what it is please?

[wobbly]

Impregnated cotton fibre rotary deburring wheels for die grinder use.Most famous brand is RexCut.
Mounted on 3mm or 1/8 shaft.
Perfect for use on plated cylinders.

[vro46i]

Impregnated cotton fibre rotary deburring wheels for die grinder use.Most famous brand is RexCut.
Mounted on 3mm or 1/8 shaft.
Perfect for use on plated cylinders.

Hi Wobbly, I just looked up the product you mentioned. In my previous life, I was an airframe structures repairer, I have encountered many deburring tools but I can't say I have come across this one.
Great! another tool to add to the arsenal. Thanks for the tips.

[Frits Overmars]

I had a flash of inspiration the other day when I saw a picture on here of a boost port with the floor up away from BDC - keeping the flow away from that piston radius.
This is probably easier than making a piston radius start and stop before the boost port , and then having to grind the port timing correction as well.Forget probably. Damn sure it's easier! Why didn't I think of that? Thanks, Wob and whoever posted that picture.

[andreas]

Motul 7100 with ester blend, it can harm the seals due to the esters, or that is a notion from the past? Also the 710/800 is offered for a good price occasonally -they are good?

[F5 Dave]

7100 is recommended in my Beta manual for injection. Motul are owned by Mobil I believe.
Sounds like you've been on some internet forums. :shutup:
I ran 400 and then 800 for like 2 decades on race bikes with no seal damage, like ever.

[andreas]

Aha, Thanks.
Actually youtube is the culprit

[F5 Dave]

Caltex petrol in the 80s had Boron (marketing p.o.d). I'm not sure if it was good or bad for the Bore, but you'd bet that opinion would depend upon who was lining your pockets.

[wobbly]

Several years ago I tested a huge number of oils for a customer on the dyno. It was a KT100 Yamaha on direct drive and the top guys were running them real hot.
Short story is that all the pure synthetics such as Motul 800 , Elf 976 etc lost power big time when run on the edge , and visible piston wear marks quickly became visible.
Then on a new piston I ran various semi synth and straight castor products.
All tests went to 680*C in the header and ran 20:1.

The loss of power at very high egt dissapeared using Elf semi syn 909 and Motul Kart GP ,Castrol M , Maxima 927 etc.
I tried using 909 in Avgas but it had severe problems with seperation if left to sit.
So I now use Motul Kart GP in racebikes on Avgas as well as karts on pump fuel - never had any issues.
I have a few customers that use Vroom , but thats doing tuning properly with a weather station and egt - its so clean the piston has virtually no brown marking even after a whole race weekend.

[OopsClunkThud]

As for the impact of 710 or 800 on the seals, I ran motul 800 50:1 in a 130cc vespa in a 3000 mile cannonball run, followed by many more 1000 mile endurance runs over several years (sitting for months in between). All at high speeds (for a vespa) EGT at 600-675C, and never had an issue with the seals (or anything else lubrication related).

[F5 Dave]

Why on earth would Motul have a different formula for karts being such a small market? (Actual question) I'd assumed it was 800 repackaged. Actually a kart guy had told me that.


Actually today I got my Beta manual on thumb drive today. It recommended some brand I'd never seen. The manual I'd downloaded from the Norf Mercan site said all Motul products.

[andreas]

Several years ago I tested a huge number of oils for a customer on the dyno. It was a KT100 Yamaha on direct drive and the top guys were running them real hot.
Short story is that all the pure synthetics such as Motul 800 , Elf 976 etc lost power big time when run on the edge , and visible piston wear marks quickly became visible.
Then on a new piston I ran various semi synth and straight castor products.
All tests went to 680*C in the header and ran 20:1.

The loss of power at very high egt dissapeared using Elf semi syn 909 and Motul Kart GP ,Castrol M , Maxima 927 etc.
I tried using 909 in Avgas but it had severe problems with seperation if left to sit.
So I now use Motul Kart GP in racebikes on Avgas as well as karts on pump fuel - never had any issues.
I have a few customers that use Vroom , but thats doing tuning properly with a weather station and egt - its so clean the piston has virtually no brown marking even after a whole race weekend.

Is it the Shell M with castor you mean? I heard good things about this. Doesn't seem to be castor like the others, in the Motul kart oil?

[wobbly]

Of interest a team here that has historically won damn near every Rotax class ( and before that KT100 ) have always used Shell M.
As I understand it , Shell M is a modified castor base. Once they found out about my tests they started to sell 909 to their customers - its cleaner burning than the very old tech M and makes the same power.
Karting is probably the biggest 2T market for oil world wide , and again the Motul Kart GP is a modified castor ester base , whereas 800 is a pure synthetic.

Short story on oils is this .Doing a Falex test a castor based oil will slowly wear a smooth shiny groove in the test drum , and if the load is increased the oil breaks down into its
chemical components - but these are still very good lubricants and the smooth wear pattern continues , abiet at a faster rate.
A pure synthetic has a much higher film strength , and the load required to create wear on the test drum is many times higher , but the instant the film is penetrated the loaded ball
will start tearing away metal off the drum ie the oil when it breaks down is a non lubricant.

When I saw this testing paper I immediately started using Castrol A747 , the first castor based synthetic mixed oil. That was wonderfull stuff , probably still is , but I havnt seen it for a long time.
Motul 800 and Elf 976 both pure synth oils became popular when GP racing changed to non leaded petrol , that unlike 130 octain , made best power when on the rich side.
So lube failure due to excessive heat breakdown of the oil never happened.

[katinas]

Comparisons between pressure graphs at Ex port with Honda ATAC in opened and closed position. Certain rpm favorable for open position.
In opened position, little weaker and shorter at negative side ( purple ), weaker and longer at positive side ( yellow/green ).
In both ways helps to keep mix in cylinder at mid-range.

[andreas]

Found in the compartment of useful things, aka the car. It's still available here but also suffers from separation.

[SwePatrick]

Is it the Shell M with castor you mean? I heard good things about this. Doesn't seem to be castor like the others, in the Motul kart oil?

I´m running Shell Advance Racing M, blends perfect with alcoholfuel as methanol,ethanol,e85, also blends with petrol.
Some say it is out of production though?

Funny thing, dunno why.
But after a while depending on exposure to light, when blending in fuel it first becomes beige, later on it becomes purple.

[trevor amos]

Wob, Amazon have A747 in stock, checked this morning, for around £20 might be worth a modest investment. In addition thanks for all the great help and advice you have freely given over the years, without you, Frits and Jan we would all be far less informed, just to say thankyou seems poor reward!
Regards, Trevor

[JanBros]

since weare discussing oils, don't know if it's available down under but since i use Putoline RS959, i haven't had any engine failure in 15 orso years. use it in my KR1S on the road and track, in my KDX200 and in my MX-mopeds.

[Condyn]

I think this is the first can o worms topic I have seen on here. I suppose I will add to it. Redline 2t racing oil for the past several years without any issues.

P.S. How does my spark plug look? Not

[jonny quest]

I tried Klotz Benol 30 years ago for some reason. It's not good for cold weather, but it smells good and really seems to work well. No bridged exhaust port wear compared to other oils. And I don't drill the holes in piston for bridge lube.

[peewee]

benol works good in methanol and nitro . maybe its not the cleanest stuff but thats not something i ever cared about

[Henrik Y]

.
Hi Henrik Y. Thanks for posting your Suzuki GP project. I loved the hand shifter modification your made that makes riding easier for you.

Here are some of the details about our gear box conversions....

I've bought a 110mm kart rod for 15mm/20mm pins to fit the vespa pistons. I don't feel like messing with the crank and try to bore it out as that can easily get screwed up with alignment and such so instead I'm grinding the crank pin down to 19mm on the ends. And while doing that I also make it eccentric for an extra 1,7mm stroke. The aluminium sleeve to the right is used for final dimension polishing with polishing compound.

350146
350147

I received the RG125 gearbox and it looks very similar to the GP125 gearbox. The splines are a little longer on the clutch side so might need a spacer or something but that remains to be investigated further. The selector forks seem to fit as well, might have to take of a few millimeters on the base that slides on the pin for clearance on one of them. It has the same style of clutch push rod so no drilling needed.
Instead of spacing the whole engine apart I'm thinking about cutting the wall with the bearings and reweld it further out and then modify the left side of the case for the selector drum. Instead of the oil plugs spring pin to hold engagement points against the drum, the RG drum has a "sprocket thing" slid over the left end so will have to build something there. If the selector drum wasn't cast iron I would've welded up the right side and drilled holes just like the GP drum but oily cast iron could become a cracking mess so I rather avoid that if I can.
350148
350149
350150

[peewee]

nice project henrik. i once had to use a larger crank pin in a smaller hole and thought of machining down the ends but decided against that for fear of it shearing. a shop bored the crank wheel holes larger and its worked great so far. i hope you have no trouble from the pin

[Henrik Y]

nice project henrik. i once had to use a larger crank pin in a smaller hole and thought of machining down the ends but decided against that for fear of it shearing. a shop bored the crank wheel holes larger and its worked great so far. i hope you have no trouble from the pin

I will make sure to have a small radius along the transition and polish it so there's no scratches that could induce any cracks. There are eccentric pins being sold and used and I haven't found anything about them failing so I'll give it a go.

This was a first test piece and that's the raw grinding and leaving scratches like the in the corner might be a bad idea.
350151

[F5 Dave]

Yup easy to do. Was very careful with radius etc.

Broke twice when on long tracks. Bored out and used bigger pin.. problems over. Find a decent toolmaker.

[peewee]

well if your forced to use a step pin maybe youll be ok if you put the biggest radius you can into the step. a matching radius in the crank wheel should help to get a large radius on the pin. but a sharp step i think is very risky

[speedpro]

I had a stepped pin made which lasted until I retired the engine. Started with a blank and ground 20mm ends with a 22mm centre with an offset to reduce the stroke. I cant remember the material but it was heat treated once complete. I rebuilt the crank after the bearings failed but the pin was still good.

[HenkS]

since weare discussing oils, don't know if it's available down under but since i use Putoline RS959, i haven't had any engine failure in 15 orso years. use it in my KR1S on the road and track, in my KDX200 and in my MX-mopeds.

Putoline RS959 :clap:

[wobbly]

Stepped pins can be made to be reliable , but its so much easyer to use a CNC spark errosion process.
A good operator will know what copper electrode size to use and can adjust the current to get a dead straight sized hole on exactly the correct stroke.
Ive done this several tines now , with only one hole being a little tight.

Edit - its really good for destroking , as you make the new hole on center , but oversize , and use a spacer sleeve to re establish the press fit.
That way the actual new hole size is immaterial , as long as they are all the same.
Depending upon the flywheel OD lengthening the stroke this way could make the web too thin above the pin hole.

[ken seeber]

DCI update:

So, with ever so many distractions, have made up a dyno and run it with a standard ARC kart engine, with just the one pathetic carby...

Next is the all important run with the 3 carbies and see if the whole thing is a winner or a failure.

The actual dyno can provide any amount of absorption capability, but is a real prick to get steady readings, ie to hold a constant speed.

However, given this lack of control, I can sort of get any reading/result that I want..:laugh:

350183350184

[TZ350]

.
2Stroke Stuffing makes progress on his eddy current dyno:- https://youtu.be/9IcUQfxCCUo

[jfn2]

Hello Frits:
In working with your scavenging concept drawing, I want to check my leading and trailing direction angles in an old school cylinder, and try to adjust as necessary. The engine is similar to a TZ 350 twin. It was mentioned earlier that the TZ 350 "A" port leading directional angle was to large and therefore allowed too much short circuiting. The angle I come up with for this engine is 55*. The engine I'm working with has a leading directional angle of 53*. Pretty close. In your concept drawing your example shows a leading directional angle of 30* for the "A" port and it shows it intersecting the bore center line +/- 3/4 of the way down the bore center line from the exhaust port side of the cylinder. When drawing things out on paper, for my engine, the 30* angle line doesn't hit the bore center line until past the 3/4 mark. I went back to your drawing and measured, from the drawing, the 'leading distance' from the center point on the bore center line to where your 30* line intersects the bore center line and came up with +/- 22% of the bore dia. Drawing this up using my engine bore of 62mm dia and using the 22%, I came up with, instead of a 30* angle, a 37* angle. My question is...... Is the angle more important or is the placement of the intersection point with the bore center line more important? I hope I was not too confusing.
Also could you explain a little more about the 'sum' of the axial scavenging direction degrees and how that is measured?
Thank you, jfn2

[JanBros]

my simple brain (compared to Frits') says :
not only look at the leading/trailing angles, but also the position of the port in the bore. consider exactly the same port, but if it is positionned closer to the exhaust port, it will need sharper leading/trailing angles to intersect at the same point on the centerline in the bore than a port that sits further away from the exhaust port.

you can play with this in my excel, where you'll see that changing the "center location" of the port also changes the intersecting points.
in the end, the angles themselves are not so important, but the combination of your STA-numbers and the angle of the scavenging column are what matter.

excel : http://users.telenet.be/jannemie/JanBros%202-stroke%201.2.xlsm
"manual" : http://users.telenet.be/jannemie/JanBros%20%202-stroke%201.2.docx

[flyonly]

Ignition timing for a 50cc being tuned for top end only. Where should it end up? I know it’s a combination of many factors and it’s a balance of them all but I expect there is a target of everything was optimal.
Looking for any advice/guidance. Not sure if I should use less of the data points in the first half of the curve. It doesn’t start to produce until 11.5k till 14.25k
https://uploads.tapatalk-cdn.com/20211127/e71a61248dd26e607da284872af41b50.jpg


Sent from my iPhone using Tapatalk

[wobbly]

Simple answer is 15* at peak power , if the com and squish are done correctly for the fuel,.
You can flat line the bottom end @ 28* to where the PV starts to open or where the engine obviously starts to come onto the pipe.
Advance past peak power depends on how much overev to max useable rpm there is , usually anothe 5* , then flat line at 10*.
If you have too much overev retard , the egt will keep climbing in top gear against the aero load .
Then you have to use extra fuel to cool the top end egt , not make Hp

[flyonly]

Simple answer is 15* at peak power , if the com and squish are done correctly for the fuel,.
You can flat line the bottom end @ 28* to where the PV starts to open or where the engine obviously starts to come onto the pipe.
Advance past peak power depends on how much overev to max useable rpm there is , usually anothe 5* , then flat line at 10*.
If you have too much overev retard , the egt will keep climbing in top gear against the aero load .
Then you have to use extra fuel to cool the top end egt , not make Hp

Currently running 15.1:1 compression with a reasonable squish. Have another insert which would increase it a little more. So I should be bringing the final timing back and building in the over rev. My EGT is still too low I think. It’s in the mid 400. Have a new sensor coming with an open tip. 150mm from the piston face. Is that close enough?


Sent from my iPhone using Tapatalk

[wobbly]

What is the fuel and what power is it making ( what engine bore/stroke , whats peak power rpm to see what the bmep is ).
As with a low bmep ( low dynamic com ) you can run more static com.
What do you mean " reasonable " squish. You should be running the minimum allowable squish height short of clipping the head with an overev , and shoot for 38M/s squish
velocity in most cases - generally around 50% area , and in a 50cc probably 0.55 squish.
MSV is just a guide as if its done right , there is virtually no squish clearance above peak power.
EGT tip should be on the header centerline about 3X Bore from the piston.
400* isnt even warm , all race engines run between 600 - 700 *C depending upon the fuel and application.
Here is an example with peak power at 13,000 , overev to 15000.

[Frits Overmars]

Hello Frits... In your concept drawing your example shows a leading directional angle of 30* for the "A" port and it shows it intersecting the bore center line +/- 3/4 of the way down the bore center line from the exhaust port side of the cylinder....
Is the angle more important or is the placement of the intersection point with the bore center line more important?
Also could you explain a little more about the 'sum' of the axial scavenging direction degrees and how that is measured?The placement of the intersection point with the bore center line was not mentioned at all in my scavenging concept. I hope this answers your first question.
Your second question is one of those seemingly simple questions for which there is no simple answer.
In my "Leaning tower of Pisa" treatise I did my best to describe the fluid dynamics of scavenging without formulas. The formula for the axial scavenging angles was unavoidable, but it caused an avalanche of 'what is an arctangent?'-questions. But I do not intend to start a trigonometry course here...

Calculating the axial component of the combined scavenging flows is not simple, and neither is measuring it. It can be done if you are a millionaire (which I am not).
Google 'COMSOL Multiphysics' and you will see what I'm on about.

[Niels Abildgaard]

Deleted as nonsense

[wobbly]

The crossing point of the A port front wall with the centerline is dependant upon the bmep , and that is largely set by the pipe efficiency.
A fatter pipe with steep diffusser angles needs the crossing point close to 1/3 from the boost port to the bore center.
Lesser pipes ( thus lesser bmep ) are around 1/2 way from the boost to bore center.
Thats just my observation no science involved at all.

[SwePatrick]

400* isnt even warm , all race engines run between 600 - 700 *C depending upon the fuel and application.


This is quite interesting.
As i have noticed alcohol fuel as methanol makes the best power at ~450 degrees with probes as you mention(and e85 has similar levels).
But!
I have also noticed that Pipetemp is affecting powerband the most, power secondary.
I can get almost the same power at different rpm´s depending on temp.

This is very useful in dragracing, at the launch the torque is at a lower rpm level and running down the strip the temp gets higher and moves the powerband upwards, allowing for more topspeed.

And as a little bonus for those who are interested, i´ve made a dynorecord again with my tzr250 engine running on E85
90.7hp at ~11000rpm(quite low rpm, and what made me post this entire post), exhausttemp starting at 430 degrees and climbing to 460 degrees at the end of the pull.(pipes are tuned to get peak power at ~11800rpm at ~600 degrees, my pulls in my dyno is quite short so the temp doesn´t rise as it should)

How did i get this huge gain?
Well, i´ve been careful with ignition as this engine seems to like very high values (22 degrees at peak power, had 20 before)
And as i am planning for new pistons and new plated bores i said to my self, to heck with caution, let´s send it =)
I raised the curve even more at the left side of the peak, but can´t remember how much.

It instantly gave me ~7hp.
I´m sorry to say i don´t have any movie of the pulls, but i got a screenshot of the curve(compared to old record)
Almost no weathercorrection also, it means that the engine actually really produces that number. :eek5:

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[jfn2]

JanBros
I do see that you can play with the concept and I will in time. I just have not done it yet. Thank you for offering that excel sheet and manual. I will use it.

Frits
I thank you for your reply and, as always, look forward to more of your wisdom both said and unsaid. I just have to train myself to read the unsaid parts a little more diligently. If I may comment on your 'Leaning Tower of Pisa' treatise. It was the most comprehensive writing I have seen. I have a pretty good little library on 2T engines and none of them could explain the workings of a 2t as well as what you wrote, at least that I could understand. Many thanks.
I also looked up 'COMSOL Multiphysics' and I see what your on about.

wobbly
Thank you. That info and what Frits said (and didn't say) gives me some parameters to work with in JanBros's excel sheet.

[lodgernz]

I'd like some advice please from the more experienced tuners here. Would you say this cylinder has a steel or cast iron sleeve, or is it Nicasil?

Sorry for the poor photos, they are the best I could get, and as it's a Japanese wesite, of course there's no information except what engine it fits.

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[andreas]

A slight umbra sheen tells you it's nicasil, as does the lack of a perfectly round separation line.

[wobbly]

I have no experience with E85 , but if you gained a bunch of Hp with the peak also at 22* then that simply means your compression is too low.
Running Methanol , when the com is correct , the ignition timing ends up back at exactly what was best for petrol,
In a 125 MX based engine we ran around 16 : 1 then on Meth over 18 : 1 but with more advance it had to go so rich it lost power to stop it seizing.

[SwePatrick]

I have no experience with E85 , but if you gained a bunch of Hp with the peak also at 22* then that simply means your compression is too low.
Running Methanol , when the com is correct , the ignition timing ends up back at exactly what was best for petrol,
In a 125 MX based engine we ran around 16 : 1 then on Meth over 18 : 1 but with more advance it had to go so rich it lost power to stop it seizing.

Yes, i actually decided to run quite 'low' compression.
This to try to get pipetemp faster as alcohol fuel is quite hard to get temp fast, especially when running only 1/8 mile on the strip.
(when testing compression i still got 170-175psi, normal for a oem dirtbike running on crapfuel)
And secondary i´m also having a nitrousoxide system to activate when needed, thereby the 'low' compression.
I´m shooting about 20hp, and when activated it moves the powerband instantly up about ~1000rpm.

If i would have built a dedicated trackracer i would have ran about 200-220psi and tuned the pipes a little bit different.

E85 i would say is the best fuel that is easy to get, cheap and about 103-104 octane.
You instantly get ~7% more power if tuning it correctly, with no other mods.

[wobbly]

I would try another tangent. Methanol makes the same power when run really rich , but I have found that the idea of using retard , or low com to get more heat in the pipe does not work at all.
All that happens is you get more , cold , unburnt mixture being dumped into the pipe.
With super high com you can get close to petrol pipe temps initially , by not going overich , then add some more fuel ,or a little retard to prevent deto or piston grief at peak rpm/load.
By then the pipe is already as hot as its going to get.

[SwePatrick]

As is for now i run Ethanol(e85) But i have tried higher compression on methanol before, it actually didn´t turn out so well.
Best numbers got way back then was with 15.5-1 in compressionratio.
That was my single 212cc kawa kx250, it produced 69+ at the wheel as best.

[Niels Abildgaard]

As is for now i run Ethanol(e85) But i have tried higher compression on methanol before, it actually didn´t turn out so well.
Best numbers got way back then was with 15.5-1 in compressionratio.
That was my single 212cc kawa kx250, it produced 69+ at the wheel as best.

Can it be explained by friction ?There is a thermodynamical small gain going from 15 to 16 but there is also a at least 6% rize in friction from the piston ring

[Frits Overmars]

Frits
I thank you for your reply and, as always, look forward to more of your wisdom both said and unsaid. I just have to train myself to read the unsaid parts a little more diligently.
If I may comment on your 'Leaning Tower of Pisa' treatise. It was the most comprehensive writing I have seen. I have a pretty good little library on 2T engines and none of them could explain the workings of a 2t as well as what you wrote, at least that I could understand. Many thanks.
wobbly
Thank you. That info and what Frits said (and didn't say) gives me some parameters to work with in JanBros's excel sheet.Jeff, thank you for your kind words. Now I wonder: what is it that I 'didn't say'? Are you perhaps referring to information in pictures ?

EDIT: I think I got it. Were you alluding to "The placement of the intersection point with the bore center line was not mentioned at all in my scavenging concept" ?

[lodgernz]

A slight umbra sheen tells you it's nicasil, as does the lack of a perfectly round separation line.

350204350205

Thank you Andreas. Anyone else care to comment?

[wobbly]

It must be a nicasil , as the spigot is fully coated on the end , but the bore edge at the transfer ducts is " ragged ".
I ssume also they have taken the chrome flash off the top deck as that is only a narrow band.

[lodgernz]

It must be a nicasil , as the spigot is fully coated on the end , but the bore edge at the transfer ducts is " ragged ".
I ssume also they have taken the chrome flash off the top deck as that is only a narrow band.

Thanks Wobbly.

[SwePatrick]

Can it be explained by friction ?There is a thermodynamical small gain going from 15 to 16 but there is also a at least 6% rize in friction from the piston ring

I dunno actually.
But those 6% increase might not be comparable to engines total friction.
Say the ring stands för 2% of engines total friction.
And 6% increase of those 2% isn´t much at all, 2.12%

[jfn2]

Hello Frits

Now I wonder: what is it that I 'didn't say'? Are you perhaps referring to information in pictures ?
EDIT: I think I got it. Were you alluding to "The placement of the intersection point with the bore center line was not mentioned at all in my scavenging concept" ?


Yes, I was alluding to that. If this intersection point was of no significance why did you place the 'Trailing and Leading Distances' markers on your drawing? I just thought that the placement of the column in the bore would be critical to all the other measurements. I understand that the 'position' angles are very important also to achieve this intersection point but since about 99.6% of us are trying to change existing cylinders it's not always possible to change where the ports are located to the extent needed to achieve the 30* angle. Therefore my question...Which is more important, the angle of the leading edge or the intersection point on the bore center line? I also understand this is about reducing the short circuiting problem. I'm just trying to do the best I can with what I have to work with. Thank you very much for all of your help. We keep plugin away.

[TZ350]

I had to draw pictures and high light stuff to get my head around this.

Pic 1. As more power is developed, a hole/dip (Point B) appears in the the power curve just before max output (Point A).

The drivability of the bike is affected by this dip just before max power.

There is a trade off between power and drivability. (as we all know)

The main things that make more power, are, and in order of priority (1) the primary transfer tangental angle, (2) the inner transfer port radius, (3) the main transfer port axial inclination, (4) and main transfer port open size and shape. All high lighted in pic 2.

Pic 3 data from tests that show the trade off between power and drivability for the different variables.

Pic 4 configuration of the better test cylinders.

Get a copy of the paper from here:- http://www.2stroke-tuning.nl/media/pdfjes/porting.pdf

.

350208350209350206350207

................

[TZ350]

Here is a little technical story for the coming Christmas days. Its official title is Transfer Theory, but I call it

<center>The leaning tower of Pisa<center>
<center>http://i15.servimg.com/u/f15/15/75/62/05/pisa_110.jpg<center>

<center>Transfer theory part 1<center>

<center>the central column

<center><center><center><center><center><center><center><center><center><center><center><center><center><center><center><center><center>..............

Originally posted by Frits</center></center></center></center></center></center></center></center></center></center></center></center></center></center></center></center></center></center></center></center></center></center></center></center>

[Frits Overmars]

If this intersection point was of no significance why did you place the 'Trailing and Leading Distances' markers on your drawing?I did it to show the coherence between the old way and my way (do I sound like Frank Sinatra?), like it says in the Leaning tower of Pisa-treatise:
Most two-stroke people define radial scavenging directions by quoting the distances where the ports would intersect the center line (the leading distance and trailing distance in the drawing below left). Gordon Blair used that notation in his publications, and 95% of us followed suit. But there is a better, more universally applicable way.350212

[husaberg]

<center><center><center><center><center><center><center><center><center><center><center><center><center><center><center><center><center>..............

Originally posted by Frits</center></center></center></center></center></center></center></center></center></center></center></center></center></center></center></center></center>
some of my best writing;)
of my Plagiarised content anyway...

[jfn2]

Frits
Again thank you very much for your reply and patience. It's finally beat into my head.

[TZ350]

.
2Stroke Stuffing's adventures continue. Getting the 24/7 engine running for testing the dyno. https://youtu.be/7ShU3YnFOpw
This so very much reminds me of what a lot of people at the sharp end go through developing their bikes for "Bucket Racing".

[Vannik]

.
2Stroke Stuffing's adventures continue. Getting the 24/7 engine running for testing the dyno.
This so very much reminds me of what a lot of people at the sharp end go through developing their bikes for "Bucket Racing".

He is now discovering why most development is incremental, and even then you can get very lost. Making a paradigm shift is sometimes very challenging.

We are all holding thumbs he finds his way!

[Ns1Montesa]

I'd like some advice please from the more experienced tuners here. Would you say this cylinder has a steel or cast iron sleeve, or is it Nicasil?

Sorry for the poor photos, they are the best I could get, and as it's a Japanese wesite, of course there's no information except what engine it fits.

350199350200

This cylinder looks like a alu clone of the nsr75/ns1 (47,5mm bore) cast iron ones. The Bikes were mainly sold in spain.
Lodgernz, do you have a link to the homepage where I can find these cylinders?

Greets

[lodgernz]

This cylinder looks like a alu clone of the nsr75/ns1 (47,5mm bore) cast iron ones. The Bikes were mainly sold in spain.
Lodgernz, do you have a link to the homepage where I can find these cylinders?

Greets

Actually made for the NSR80 & CRM80, but will fit perfectly on the NS-1 75cc crankcase. It will require the corresponding 49.5mm piston.

https://japan.webike.net/products/24635158.html

[tdc211]

Hello. Haven't been on here for a while.
Been playing with cars and working.

As some of you may know. I played with the old model ktm 105
Alot. Changed the transfer port tunnel shapes,timings and Area's, pipe dimensions ,export, even tried exhaust extension, All the basic things and some of the other things that's been talked about on here . Leaned how bad the A ports can short circuit cause of this engine . Learned some things on B port volume/shape cause of this engine. Tried alot of pipes I made.
took 3 years to make 34 hp,up from 27.5hp. With the old style cylinder n epoxy. My new more modern cylinder 105 1hp less.. Couldn't of done it with this forum or Frits Jan and Wob or engine mod 2t and alot of head scratching. Wob even helped me with a yz85 flat track eng. Thank you all very much.


I had a guy give me a new yz 85 that was bored and stroked.
To see what i can do with it.
he wasn't to happy with it as is. I see some very obvious things I can make quick work of. Yamaha tightened up the transfer port volumes. These are much longer ports than I am use to. Different roof angles than I am used to . Completely different shape ports than I am use to. So I am sure different results than I am use to. Here are 2 inner radius transfer shapes.
I know how the shorter shape works . (For now)
Dis regard the tails on right side. Bottom of bore ends on right side bend. Any input how thess longer ,different shape will work? I have a idea/maybe. I do own a flow bench. But where talking 2 strokes. So I am sure, I am in for some surprises when I dyno this thing. I need make port molds yet. 350220

[TZ350]

.
350226 350227

Ok, it did not work as expected so what is going on here.

I imagined that the depression behind the slide would draw fuel up the purple tube attached the power jet pickup. Fuel flow being moderated by the solenoid valve.

The Ignitec ignition has an option for PWM of a power jet and I am using this to control the solenoid valve. With the frequency set at 2Hz ( the solenoid should handle that) and PWM at 100%. I was expecting the engine to run way over rich but nothing happened. No extra fuel?

The solenoid works, I tested it by sucking on the tube when the solenoid was activated, so all good there. And I was expecting that at WOT fuel would be sucked from the tube just like it is with the main jet. And at closed throttle it would gush out like a fountain.

But nothing, could it be that the pressure recovery on the engine side of the slide is such that there is no real depression there ????. Any suggestions would be welcome.

[Tim Ey]

Hi Teezee,

I think it is certainly not helping, that you force the fuel to participate in a exhausting long rollercoaster ride before joining the game :rolleyes:

I would use the valve the other way around: connect the 90° bent to the vaporizing tube and make a short and straight hose down in the chamber. No bends, no long paths to go.

Also I would point the vaporizing tube in the center of the bore. (Idea stolen from wobbly)

If that does not help at all, mount a brass plug in the hose with a 0.2mm hole in it. That will act like a check valve and no fuel will flow back into the chamber (Idea stolen from Suzuki RGV powerjet hose)

Cheers
Tim

[F5 Dave]

It is pretty hose.

Pretty big hose. Usually very small bore.

[wobbly]

Its normal to operate the valve at something like 12Hz and vary the % to vary the flow rate.
Try using the solenoid to operate the std powerjet , just to see if that well provrn system actually works.
Then stick a piece of clear tube on the jet behind the slide down into a small container of fuel next to the bowl and see if fuel is drawn up on the overrun.

[TZ350]

Hi Teezee, I think it is certainly not helping, that you force the fuel to participate in a exhausting long rollercoaster ride before joining the game :rolleyes: I would use the valve the other way around: connect the 90° bent to the vaporizing tube and make a short and straight hose down in the chamber. No bends, no long paths to go. Cheers Tim


Pretty big hose. Usually very small bore.


Its normal to operate the valve at something like 12Hz and vary the % to vary the flow rate. Try using the solenoid to operate the std powerjet , just to see if that well provrn system actually works. Then stick a piece of clear tube on the jet behind the slide down into a small container of fuel next to the bowl and see if fuel is drawn up on the overrun.

Thanks for the tips.

Now, I have become really interested in what the actual pressure is behind the slide. At closed throttle the small amount of airflow across the pilot jet orifice causes a venture effect but the actual pressure behind the slide might be quite high. There may not be that much differential between the front and back of the slide. When I get a chance I am going to measure it.

[speedpro]

Your previous measurement of crankcase pressure at various times should be a clue I'd have thought.

[TZ350]

Your previous measurement of crankcase pressure at various times should be a clue I'd have thought.

Yes. True, ...... :facepalm: where was my head at. Looks like I trapped myself with four stroke thinking again. Where the pressure behind the slide of a 4S is really low.

And if the average two stroke's crankcase pressure is close to atmospheric at closed throttle then of course the pressure behind the slide must be close to atmospheric too. So little suction there. And when it is on WOT the average crankcase pressure is only a little lower, but not by all that much. The air moves through the 2S motor in a series of short pulses. Unlike a 4S which is more pumping action than pulse action.

[Muhr]

The pressure drop in the carburetor veturi has a lot to do with speed.
You should have dynamic pressure drop for close to 200 mm at peak power. It does not happen to be checked that it should be invert polarity (do not know what it looks like on ignitec but have made the mistake myself)

[TZ350]

.

The pressure drop in the carburetor venturi has a lot to do with speed. You should have dynamic pressure drop for close to 200 mm at peak power.

Yes that makes sense, the average crankcase pressure does not change much but at WOT the max and min crank case pressures are much greater than at lesser or closed throttle. And with large swings in crankcase pressure there will be larger gas speeds through the inlet venturi.

[ceci]

I was wrong, he talks about the rsw 2 which is indeed the 500.

he maintains that there is only one injector. I do not believe it. one cannot be enough to feed properly

Francesco didn't lie

[andreas]

Sorry TZ, I don't have a solution to this predicament, out of curiosity I wonder; You change the original PJ outlet to what must have been an oil pump inlet- for some reason, and since he jet sits in the original over-venturi nozzle, how does it meter the fuel? But there shouldn't be less depression in this new location compared to where it was, I don't think.

[wobbly]

There must be a depression on the engine side of the slide when closed, as that is where the pilot circuit is activated from.

[TZ350]

There must be a depression on the engine side of the slide when closed, as that is where the pilot circuit is activated from.

Yes there is sufficient to draw minimal air under the slide and across the pilot jet but not sufficient to lift fuel from the fuel bowl all the way up to where I have placed my nozzle behind the slide apparently. The depression behind the slide on a two stroke at closed throttle is much much much less than it is on a four stroke.

[Muhr]

Even when releasing the throttle with gear, the flow should be the volume after clost transfers minus the crankcase low pressure times rpm on each individual occasion?

[Roflhat]

New to the forum, from Scotland!
I'm building a GP100 to take to Bonneville, only going for production records so no big changes. Basically the bike has to appear standard and have the standard venturi size. Other than that you can get away with changing internal parts. Currently I've got a sort of expansion chamber welded into the standard exhaust, barrel ported, rotary valve cut to gp125 spec, standard carb bellmouthed instead of the standard shape. Got a thin spacer under the barrel, barrel skimmed and o ringed.

Went from 9.6rwhp to around 13.6, have done a couple mods since but would love to get more out of it
https://iili.io/7XD8js.md.jpg (https://freeimage.host/i/7XD8js)
https://iili.io/7XDvun.md.jpg (https://freeimage.host/i/7XDvun)

[F5 Dave]

And the reason you didn't start with a TM100, or even KX100 is?

[TZ350]

.
Welcome Roflhat. Great to see you here. I am looking forward to following your project. Great to see its a Suzuki GP100. Team ESE's favorite bike.

[TZ350]

I'm building a GP100 to take to Bonneville, only going for production records so no big changes. Went from 9.6rwhp to around 13.6, have done a couple mods since but would love to get more out of it.

From our experience with original air cooled GP100's. 18 rwhp is realistic and 22 is about tops.

It will be interesting to see whats possible with the class restrictions you have.

[Grumph]

With those class restrictions, IMO the most cost effective add-on power is a NO2 bottle hidden in the frame.....

[Roflhat]

And the reason you didn't start with a TM100, or even KX100 is?

Not too late to change, basically went for the fastest production 100cc bike in 1980 (class is for classic which is pre 1981).

18rwhp I'd be very happy with. I took it down to Mick Abbey for tuning last year, that's him in the photo with the exhaust. Big improvement after that but his knowledge isn't specific to GP100 or as in depth as the info in this thread.

How much of your GP125 recipe would be applicable to the GP100 given the exhaust + carb restrictions I've got?



GP125 18+ rwhp: skim the barrel 1.5mm and “o” ring it, thin alloy spacer plate under the barrel and Suzuki RG250 pipe. Ex opens 86 deg ATDC and Trans opens 114 ATDC, std head , inlet timing 145/55 and carb mj 95.

GP125 20+ rwhp: skim the barrel 1.5mm and “o” ring it, thin alloy Spacer plate under the barrel and Suzuki RG250 pipe modified to RM125 specs, KX80 ignition. Raise the exhaust to open 83 deg ATDC, and widen to 70% of the bore, cut 30 deg from the closing point of the rotary disk, so inlet opens 145 BTDC and closes 85 ATDC. Set the mj 105 and ignition timing, 26-28 BTDC using a dyno.

[TZ350]

.

350244 350243

Once we opened up the "B" and "C" transfers we started to make some real power with the GP's.

Looks crude but was very effective.

350240 350241 350242

Porting the cases to match the cylinder we broke through in some places. We learnt to glue the cases with JB Weld before porting them.

We never had any problems with the glue coming away and leaking.

[TZ350]

How much of your GP125 recipe would be applicable to the GP100 given the exhaust + carb restrictions I've got?

Pretty much every thing. All the port and inlet timings. Maybe not the Honda RS125 chamber although we do use it with the 110cc engines.
The GP125 looks exactly like the 100 one except it is 24mm not 22. I would use the GP125 rotary valve cover, disk and carb if you can. Carb size is not that important, we have had 30rwhp out of a GP125 with a 24mm carb.

Exhaust opens 80deg ATDC for 200deg Duration 70% bore width. Transfers open 116deg ATDC for 128deg Duration. Inlet port opens 145 BTDC closes 80 ATDC.

[Tim Ey]

.
We learnt to glue the cases with JB Weld before porting them.

There is an alternative.
350251
350252
350253
I am selling these mostly to Vespa tuners.
21€ including shipping Worldwide.

If anyone needs it write me an email
mail [at] overrev.de

I hope this add is ok with all of you - otherwise let me know & I will delete it.

Regards
Tim

[Roflhat]

Thanks very much for the info, photos will be especially useful. What's the advantage with kx80 ignition? I've got an electronic ignition kit from malaysia somewhere on there currently

Have to use the standard carb, 22mm for the rules unfortunately

[F5 Dave]

Ahh, didn't realise the year limit.

[TZ350]

What's the advantage with kx80 ignition? Have to use the standard carb, 22mm for the rules unfortunately

Would not worry to much about the 22mm carb. Plenty enough air will flow through it. Only draw back is a little loss of over rev capability, not a big deal for Bonneville.

KX80 ignitions are fixed advance, we used to run them and they will work but lack the ability to be correct for "low end drive" "max power" "over rev". Un like a digital ignition the KX80 has no curve so it is compromised as you cant bend the ignition curve to get the best of everything. Maybe ok for Bonneville??

We use Ignitec DCCDI Race1 or Race2 Ignitions. No more top end power than the KX80 but a much better power curve and ride able bike. The Ignitec DCCDI can be powered by a 12-14Volt battery and gives a good CDI spark.

On our later bikes we used the center from a GP's flywheel to modify a Chinese after market ignition unit which was re wound by hand for 12Volts. These bikes had a Voltage rectifier regulator and capacitor to power the Ignitec. No battery. We call them push and goes.


How to make a decent light weight racing 12 Volt generator stator for the Suzuki GP/TF/TS RG50 from a Lifan after market magneto kit. We have spun these to 14,000 rpm plus on the dyno and they have proved reliable on the track.

[Roflhat]

Excellent, buying a barrel or maybe 2 in case I mess it up. Already got a spare set of cases and a pile of bits, will probably take my complete engine out and just build another one to your specs
Will any year KX80 ignition work? Not so many of those bikes up here, will probably have to buy from abroad.
www.ebay.co.uk/itm/224691973171 - some great photos of this one

[Condyn]

We do similar with our snowmobile race ignitions. Press out the rivets and weld the desired mag onto the hub.

[TZ350]

Excellent, buying a barrel or maybe 2 in case I mess it up. Already got a spare set of cases and a pile of bits, will probably take my complete engine out and just build another one.

You can never have to many spares.... :laugh:

I was able to triple exhaust port a cylinder. Worked great, then ruined it by trying to improve it. A lot of hand work with long drills and porting tools. But it is possible to do and keep the cylinder looking standard from the outside.


Will any year KX80 ignition work? Not so many of those bikes up here, will probably have to buy from abroad.
www.ebay.co.uk/itm/224691973171 (http://www.ebay.co.uk/itm/224691973171) - some great photos of this one

Yes, but the later ones like the ebay picture may have a heavy retard to protect the KX engine. There is also a little bit of machining to the stater plate required to fit the GP100 mount and to clear the main bearing boss.

[Roflhat]

What porting tools do you use? Needing to get a new dremel anyway
Will try find an earlier ignition, would prefer plug and play

[philou]

http://www.ccspecialtytoolstore.com/90-degree-porting-tool-s/327.htm

[TZ350]

.

350260

We started with a lot of long series drills and cutters with long 6mm shafts.

CC Specialty Tools is the best and is now what we like to use. Took a while before we could afford them.

[TZ350]

.
350259

Found an answerer to my no suck problem. Going to try to just pump it in.

Doing away with the solenoid and going to use the PWM signal from the Ignitec ignition's power jet control to run the pump at whatever speed is required at the time.

[wobbly]

The Foredom flex shaft and motor kit from CC is an insane ripoff.
You can buy the exact same part on several Chinese websites for less than 1/4 the price.
Ive had two for a couple of years now with no issues at all, and I use them near on every day.
The HD Dremel flex shaft parts have been NLA for ages - I searched the net for weeks and bought what I could , but now , nothing anywhere since the company was sold to Bosch.
The Foredom flex shaft parts are cheap , but wont fit the Dremel so I have two perfectly good HD Dremel motors I cant use.

[husaberg]

I seen a flex shaft the other day?

https://www.bunnings.co.nz/dremel-flex-shaft-rotary-tool-attachment_p0730737

sorry hd?

what does the HD look like the old original ones?

https://www.dhresource.com/260x260/f2/albu/g20/M00/A0/9D/rBVaqGGGqzeAHXw4AACBn2yEOp8708.jpg
Have you tried one of those bench grinder driven shafts?
they are slow and more Hp so the drive should be higher rated

if you wanted a HD one maybe a shearing plant drive set up?
oh look Maybe $600 maybe not.
https://shearquantity.com/downtubes-driveshafts/flexible-driveshafts.html
Still spendy at half the price
https://www.shearing.co.uk/product-category/driveshafts/flexible-drives/

[philou]

the 1mc of cc spécialité tools and cheaper in Germany.

https://www.piggyshop.de/winkel-handstueck-whs-90-spannzange-2-35-3-mm.html

attention there are several types of attachment for the flexible shaft.

the tightening nut at the back of the gearbox is in the open air. it can damage the cylinder wall.

put a piece of hose over it, for example. idea taken from Macdizzy

350262

[Roflhat]

Some of the prices were a bit eye watering so I went for a 90 degree one like that from China, £65

[sniemisto]

I use NSK dentist angle piece from Chinese eBay. They are small enough to fit inside 50cc cylinder. Bearings won’t last too long with carbide burrs but they are also cheap. 2.35mm bits.

Straight 3mm bit grinder from Biltema is really good, lasts long and costs only 35€
https://uploads.tapatalk-cdn.com/20211213/2b2756a65959070e5e9cd27de66b4316.jpg

[ceci]

.
350259

Found an answerer to my no suck problem. Going to try to just pump it in.

Doing away with the solenoid and going to use the PWM signal from the Ignitec ignition's power jet control to run the pump at whatever speed is required at the time.



It is not a bad solution, but it can be a bit complicated to configure since you have to take into account the moments of inertia to start the pump and then the residual inertia to stop.
Why not try something simpler such as the pumping method of the STIHL MS 500i, but in this case carried out by the gravity of the fuel, as is the supply to the carburetor.

[TZ350]

Why not try something simpler such as the pumping method of the STIHL MS 500i, but in this case carried out by the gravity of the fuel, as is the supply to the carburetor.

Good idea. I like it very much May be where I end up.

[wobbly]

The original Dremel that everyone used for porting was called a 732 , that was the HD version originaly for wood carver types.
I found the 1MC right angle was big and hard to use - the NSK 182MC right angle and drive adapter for the flex shaft is more expensive but lasts alot longer and is alot smaller.
They are cheaper from other NSK distributors , just takes some time searching the web.

[philou]

the 182mc is referenced ic300 at NSK.

the 1mc is good for big jobs. a small one is needed in addition for the finishes and to intervene on the ports without the back of the tool coming up against the walls of the cylinder

[Condyn]

I elected for the ARTCO 1039 because I saw many reviews saying the CC Specialties hand pieces sound like they have rocks in them. The artco is smooth but there is a design flaw with the hollow shaft that threads into the ring gear. Only takes a split second down in a nook to snag your cutter and the flex shaft motor finds the weak link instantly. Snaps the $132 shaft at the thread and after you try to braze or solder it a dozen times with a magnifying glass you break down and order the part that takes 12 phone calls and a month to get. I would not buy this one again.

*edit I should not say this is an “ARTCO” because it is probably just sold by them with no label, parts list, or paperwork.

[jfn2]

Condyn
Would you please post a pic of your how you have your porting tool motor set up. I have the same tool and I never had any trouble with it or the flex shaft.

[Condyn]

The foredom motor just dangles above me. It is the hollow shaft in the hand piece that snaps where it sharply transitions to the tiny threaded end with no radius that screws into the gear in the grinders head. Partially my fault for getting wedged up in stupid places. Still, I do not care for the way that the hollow shaft was made.

[Tim Ey]

I had pretty much everything available in Europe...
Proxxon, Dremel, Foredom, JoKe....

Joke: not enough RPM

Foredome: the flexible shaft was not really flexible, the chuck was fitted with a cone and dropped from that connection ever 15 minutes.

Dremel and Proxxon: good rpm, but not enough torque.


Today, I am using this motor
https://www.zujeddeloh.de/produkte/goldschmiedebedarf/mikro_und_haengemotoren_--246/haengemotor_hm800--_3103.html
(the shaft snaps right away... This sucks)

this handpiece for rough work
https://www.zujeddeloh.de/produkte/goldschmiedebedarf/mikro_und_haengemotoren_--246/handstueck_industrieausfuehrung--_1470.html

an ebay find handpiece with 2.35 & 3.00mm chucks for fine work.

and for the fine in cylinder stuff a kavo 195 90° handpiece.

[TZ350]

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https://youtu.be/977BWjCMC8E

https://youtu.be/mS0cyt7F9js

https://youtu.be/CLn4tsz8M1s


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Flettners flying Gibs in action:- As I understand it, these are "Fly by Wire" activated and they are part of the face of the rotary valve cover and basically open/close the normally fixed aperture in a rotary valve cover. The idle circuit is a very small reed valve about the size of your thumb nail. The idle reed valve is adjusted by a screw that limits how much it can open.

[jfn2]

Condyn
When you say the motor just dangles above you how do you have it anchored or held above you. Is it just hanging on one of their holders or hanging by a nail or eye screw or wire?
I've had 3 of these handpieces and have never had any trouble. I bought my first one in 1972-3. I believe back then it was called a #57 handpiece. But I could be wrong. The one I have now was bought in 1993-4. In fact the one I have now is labeled ARTCO M-1036. Since then they have changed their numbers to 1039. I guess it's possible they cheapened up some of the components but the parts sheet for the 1039 is still the same as for the 1036 on ARTCO web page.
I have an old C.C. Specialty catalog (2009) and the parts sheet shows 2 shafts, one is a outer shaft called the 'Round Drive Shaft' and the inner shaft is called the 'Keyway Shaft'. Now I received this catalog in 2009 and the prices were Round Drive Shaft= $29.25, and the Keyway Shaft= $17.35. But like I said it's 10 years old. I don't know how much ARTCO wants but you could call.

[TZ350]

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350269

Fixed verses Programable ignition. The Red line is a fixed timing KX80 ignition on my RG50. The Blue line is an optimized Ignitec programable ignition.

[philou]

do all ignitech p2 race have input for the deto sensor? or is it an option to add?

I use the Czech deto count recommended by wobbly

I can't find the information in the documentation

[F5 Dave]

It has an optional output on det counter from memory. Then you input that to ignitech and reduce ignition several degrees. Um, what's it called again? Bugger sorry too long ago.

[wobbly]

Yes the Czech deto module can output 0-5V for data logging and or drop an output to ground ,this wire is input to any Ignitech that when grounded
it will pull out any amount of programmed static advance ( say 3* ).
Only issue is you then have no record of it happening as the Ignition response is so fast you miss seeing the deto red light , but if you have it ,you will see close to 5V on the deto data stream.
Working backward you can then find the TPS and rpm where det was being corrected , and change the advance curve to eliminate the feedback control.

I asked Ignitech years ago to incorporate an auto curve correction , but for some reason they refuse to talk to me - even though I sold literally hundreds of the things and became an international
" help desk " for free. They still owe me 4 ignitions returned for repair over 3 years ago - and guess who had to replace the customers product . I refuse to even look at one now - Ignorant fucks.

[Muhr]

Does anyone think they have the best design

https://m.youtube.com/watch?v=G8L9_XO3iCw

[HenkS]

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350269

Fixed verses Programable ignition. The Red line is a fixed timing KX80 ignition on my RG50. The Blue line is an optimized Ignitec programable ignition.

May be the fixed one was not set at the right time.
At max power both should have the same pre ignition !
At lower speed the power is the same, which should be different in favor of the Ignitech progr.
This suggests that the fixed ignition was too late.