ESE's works engine tuner

[Frits Overmars]

the short stroke means the only way to generate power is by holding up the torque at much higher rpm.
13,000 is nothing to a 50.7 stroker..13,000 is nothing to a 50.7 stroker from a piston speed point of view. But the time.areas in a short-stroker are a different cup of single malt,
preventing you from holding up the torque even before you reach 13.000. No free lunch, as usual.

[skako]

Hello wobbly, just an idea. When the fresh mixture must be pushed back in the cylinder it will find an exhaust port that is diminishing the height until it finally closes. Compared to a longer stroke engine the shape of that port could have a worse Cd on a short stroke engine because it will be not so “square”, needing an additional time to push back the mixture.

You made a good point Javier.
I have noticed this with some that had very wide and low exhaust ports, to satisfy STAex. The tests were not very encouraging. This is where the hydraulic diameter comes to the fore, which increases the Reynolds number and friction factor, which act to reduce Cd and fluid flow.
A compromise between STAex and Cd factors should be guessed.

[41juergen]

Having dyno and track tuned a 3YL/4DP TZ250 Yamaha to a win at Eastern Creek last weekend I have continued doing some development work for the future.
It has surprised the hell out of my by not responding in any way to the usual duct CSA reduction.
The stock exit is 37.5 dia and it likes nothing else except a 40 header forming a step. This increases front side and overev.
Its super finicky with intake length tuning and reed frequency , and will deto with even tiny increases in Com /MSV/Ignition/A/f or CE.
The other thing I wanted to nail down definitively is that for years many people have been extolling the virtues of cranks with cork in the balance holes , or full circle webs and or stuffing the case around the reed
to decrease the volume. I know both cases are not the same , but having measured one side and increased the volume to the usual 1.3 ratio , I now know this is all bullshit.
Sad really as the owner has a couple of super expensive filled and full circle cranks as well as a special kit version.
The pipe reacts as per normal , except it has to be alot shorter than I would expect to peak at 12500.
Its very difficult with the short stroke to get the needed STA , but its making the actual port power capability in the sim.
Anyway here is some info about the thing - Im now looking Hi and Low for a pair of 4DP - 11 or 4DP - 20 cylinders to put on it , please contact if anyone knows where a pair are hidding.

Hey Wob, sorry to say, but you made my day! :drinknsin
I'm working of that 4DP setup on my 1 cylinder bike now since a long time and didn't got that engine running well... So I gave up on the 4DP cylinders and modified 3XV R cylinders. As beeing from a street bike with the japanese 45 HP restiction, these barrels have low timings giving a lot of possibilities for mods. Finally I need to grind down the cylinder and will put the engine together soon, will report back. I can send you my .pak file, not sure if all data are correct.. (with an street air box setup and your older proposal for a pipe).

354428354429354430

[wobbly]

So joy of joys , thats is a 5 port with a drum PV that closes off the Aux ports ?
Would be cheap as well. , but alot of work - yes please send the .pack. , really interested.

So Frits , you believe I am kicking a dead horse trying to make better power at 12500 with overev to 13,000 - thats about 1200 past the original.

[F5 Dave]

Watch for cracks between aux and main. Not sure how prolific or isolated to example I saw.

[Frits Overmars]

the short stroke means the only way to generate power is by holding up the torque at much higher rpm.
13,000 is nothing to a 50.7 stroker..
13,000 is nothing to a 50.7 stroker from a piston speed point of view. But the time.areas in a short-stroker are a different cup of single malt,
preventing you from holding up the torque even before you reach 13.000.
So Frits , you believe I am kicking a dead horse trying to make better power at 12500 with overev to 13,000 - thats about 1200 past the original.The way I read it, and looking at the power curves you posted, I assumed that you wanted to make max. torque at 13000 rpm. And that would not have been a very healthy horse.

[Javier Ruda]

Hello wobbly, just an idea. When the fresh mixture must be pushed back in the cylinder it will find an exhaust port that is diminishing the height until it finally closes. Compared to a longer stroke engine the shape of that port could have a worse Cd on a short stroke engine because it will be not so “square”, needing an additional time to push back the mixture.

I think I was wrong. If the wave comes back earlier, it will be gone earlier too.

[wobbly]

Na Frits , I was shooting for peak power@12500 with overev to 13,000.
I simply could not get decent numbers @ 13000 , just as you said.
Even @ 12500 the STA predictions were maxed out at 43 Hp , and with a clever pipe and some serious fiddling in the sim that is what it made.
But it fought me every step of the way , detoing at the drop of a hat as everything was pushed so hard to get that theoretical ( but shit never the less ) result.
Makes it obvious now why the 4DP was a lemon for all those years in the 90's.

I know Rich Oliver won a bunch of USA titles with one - but even though the Yanks think so , that aint the Worlds by a long shot.
We have discovered an old guy who won some All Japan Cup races - he has a pair of super special Sugo 4DP cylinders sitting on a shelf in his shop.
Be interesting to see what was actually considered fast back then.
But the more I look into it - the 3XV TZR cylinder seems far superior in ultimate power capability.

[skako]

Hi Frits,
I have been customizing various exhaust pipes for the sims for a long time now. I try to compare most of those tubes that are published with the better ones.
All pipes are connected to the same test model in the sim (50cc).
They all have the same entrance and a total length of 825 mm. The output from the cylinder is a Wobbly (90%) concept.
The initial model I started with was the basic FOS-tube model.
I was looking for as much power and as wide a power band as possible, but so far none of the tubes have been better than these three (P1, P2, P3).
Frits, are you interested in this and could you come up with a better P4 tube on the default sim model. Pipe which would be above these three.

354432

[husaberg]

Na Frits , I was shooting for peak power@12500 with overev to 13,000.
I simply could not get decent numbers @ 13000 , just as you said.
Even @ 12500 the STA predictions were maxed out at 43 Hp , and with a clever pipe and some serious fiddling in the sim that is what it made.
But it fought me every step of the way , detoing at the drop of a hat as everything was pushed so hard to get that theoretical ( but shit never the less ) result.
Makes it obvious now why the 4DP was a lemon for all those years in the 90's.

I know Rich Oliver won a bunch of USA titles with one - but even though the Yanks think so , that aint the Worlds by a long shot.
We have discovered an old guy who won some All Japan Cup races - he has a pair of super special Sugo 4DP cylinders sitting on a shelf in his shop.
Be interesting to see what was actually considered fast back then.
But the more I look into it - the 3XV TZR cylinder seems far superior in ultimate power capability.

Without going back through old stuff and i am open to correction, but i think there was a tie up with Bud Askland and Rich Oliver at time. Pretty sure Bud had also tuned Kokinski 250 tittle bike.
Is there room in the cases to stroke the engine to 54 ish.

[Frits Overmars]

Hi Frits,
I have been customizing various exhaust pipes for the sims for a long time now. I try to compare most of those tubes that are published with the better ones.
All pipes are connected to the same test model in the sim (50cc).
They all have the same entrance and a total length of 825 mm. The output from the cylinder is a Wobbly (90%) concept.
The initial model I started with was the basic FOS-tube model.
I was looking for as much power and as wide a power band as possible, but so far none of the tubes have been better than these three (P1, P2, P3).
Frits, are you interested in this and could you come up with a better P4 tube on the default sim model. Pipe which would be above these three.
354432Hi Skako, I appreciate the offer and I was curious enough to dive into it even though I don't really have time for it.
I don't have any data on your engine so I couldn't check your diameters and lengths; I could only look at the length percentages of your pipe segments and I found clear differences. The FOS percentages are 32-34-8-26 and your percentages are 34-34-8.4-23.6. Your end cone in particular is markedly shorter.

The maximum power of 10.2 kW or 13.9 hp in your graph requires a Ø 11,6 mm end restrictor diameter, but in your case it is Ø 13 mm, preventing the engine from building up pressure, exhaust gas temperature and revs. By the way, 13.9 hp is about 10 hp below the current 50cc top level.

Finally you write: "The output from the cylinder is a Wobbly (90%) concept". But as I have mentioned repeatedly, you must not mix the Wobbly concept into the FOS concept.

[Mike Fisher]

https://www.cycleworld.com/sport-rider/dominator/ - We Ride Rich Oliver's AMA Championship Winning Yamaha TZ250 - This motor hits hard, hits now and is tuned for a rider that values top-end steam over midrange drivability. Rich confessed, “My work goes toward top-end power. I spin my engines hard and that means I replace parts more often than most, but it's worth it to me. I've worked with some good tuners over the years and Bud Aksland has answered a lot of questions for me, helping me arrive at this particular combination." Oliver's right; most of the bikes in the AMA 250 field don't see 13,000 rpm all season and peak out between 12,300 and 12,700 rpm. Rich added, “If this was a national, I'd work on the jetting until it spun even higher.”

[philou]

The maximum power of 10.2 kW or 13.9 hp in your graph requires a Ø 11,6 mm end restrictor diameter,


13mm was dangerous, 11.6mm will still more be fun
​

[Frits Overmars]

13mm was dangerous, 11.6mm will still more be fun​If it's dangerous, remove the danger; don't increase it.
But how is it dangerous? Too little cooling, too much ignition advance, compression ratio too high, squish gap too big? Bad fuel? All of the above?

[skako]

Hi Frits,
I'm glad I caught your attention. I am attaching a graph with your last recommendations, from which I started researching the best tube for my model. I know that it is not the maximum. That's why I check possible combinations before cutting the sheet and making the pipe itself. I need to perform certain operations on the cylinder, which are very limited for my capabilities.
If you can spare some time, I would appreciate your analysis.
I can send you these few pack-files for a quick check.
I apologize to everyone for some sentences that may not be well composed in the spirit of the English language because I use google translator to convey my thoughts.

354434

[yatasaki]

Skako, are those pipes/curves for standard gearbox or it is new independent sim?

[skako]

Skako, are those pipes/curves for standard gearbox or it is new independent sim?

I need to transfer the characteristic of the pipe to my program and see it exactly (and this is done manually by typing, so it takes a long time). This way, at first, I can conclude that it can use a standard gearbox.

[Frits Overmars]

I am attaching a graph with your last recommendations, from which I started researching the best tube for my model.... If you can spare some time, I would appreciate your analysis. I can send you these few pack-files for a quick check.Skako, the length percentages of the pipe segments are still the only data I can check with the info I have available, and these percentages are now in line with the FOS concept.
The initial diameter X is an important part of the concept and my first impression is that your 24,3 seems rather large but without knowing the exhaust timing, the cylinder capacity and the rpm of maximum power, this is just a gut feeling. But as I wrote yesterday, I don't really have time for it so I have to leave it at that.

[philou]

on a 50cc of 13 hp a stinger of 11.6 is equivalent to a stinger of 17 or 18 mm for a 125 cc of 30 hp.
it does not exist and the temperature will soar and burn the oil film

[Frits Overmars]

on a 50cc of 13 hp a stinger of 11.6 is equivalent to a stinger of 17 or 18 mm for a 125 cc of 30 hp.
it does not exist and the temperature will soar and burn the oil filmPhilou, you may notice a couple of things in my exhaust concept.
1: The end restrictor diameter depends on crankshaft horsepower. The cylinder capacity does not play any role in the calculation of the restrictor diameter.
2: The stinger, as you call it, should have an internal diameter of >1,2 x the restrictor diameter. For 30 hp that stinger diameter should be >20,4.

I have no data of a 125cc engine that produces 30 hp, but I can provide you with data from a 125 cc engine that produces 54 hp at the secondary gearbox shaft, which corresponds to approximately 57 hp at the crankshaft. The restrictor diameter of that engine is 23.3 mm. Do the math if you wish.
That engine did not suffer from soaring temperatures and it did not burn the oil film. It did win a number of world titles....

[philou]

23 mm is ok for a 125.
the 1st series of jollymoto for 250 rgv (125 twin) had a 19 mm stinger which caused a lot of engine failure before moving to 22 mm.
I maintain that 11.6 or 13mm is too small for a 50cc that produces some power.

[Frits Overmars]

23 mm is ok for a 125.
the 1st series of jollymoto for 250 rgv (125 twin) had a 19 mm stinger which caused a lot of engine failure before moving to 22 mm.
I maintain that 11.6 or 13mm is too small for a 50cc that produces some power.I wrote that a maximum power of 13.9 crankshaft-hp requires an 11,6 mm end restrictor diameter. I also wrote that 13.9 hp is about 10 hp below the current 50cc top level.
Now what is your definition of' "a 50cc that produces some power" ?

As for the RGV250 example: a well-prepared RGV250 engine can produce about 70 hp at the wheel or about 40 crankshaft-hp per cylinder.
This requires restrictor diameters of 3,1 x Square(40) = 19,6 mm and stinger diameters of at least 1,2 x 19,6 mm. You do the math again?
PS: it may be useful to make a clear distinction between restrictor diameter and stinger diameter.

[skako]

Hi,
I want to thank Frits for the additional comments.
After this I made minor changes to the pipe, by A.I. designed for the AR93.
The obtained characteristic is much better.

yatasaki,
here I transferred the characteristics of the standard Tomos gearbox to the graph.
It can be seen that the gearbox fully utilizes this power in the graph.
Good elasticity for your ride, on the kart track in VT.

354436354437

[Vannik]

here I transferred the characteristics of the standard Tomos gearbox to the graph.
It can be seen that the gearbox fully utilizes this power in the graph.
Good elasticity for your ride, on the kart track in VT.



Try to model it in the vehicle performance part of Post2T and also show the Power Range as done in Post2T.

[jfn2]

TZ350
If I remember correctly to use these hooks it's better to have plugs in the piston pin ends. If not the shallow hooks are better. If I remember correctly???

[yatasaki]

[QUOTE=skako;1131223231]Hi,
I

yatasaki,
here I transferred the characteristics of the standard Tomos gearbox to the graph.
It can be seen that the gearbox fully utilizes this power in the graph.
Good elasticity for your ride, on the kart track in VT.

Red curve from other graph is which I like, it would suit smaller carburetors and angles we use. I found belly diameters larger than 80mm not benefitial in our applications.
If using FOS concept you have to use different coefficient for belly diameters.
But as Frits mentioned FOS concept is general starting point.

[skako]

Try to model it in the vehicle performance part of Post2T and also show the Power Range as done in Post2T.

Hi Vannik,
I tried to put something together from Post2T.
I'm not sure if you meant this or something else.
The longest straight section of the trail in VT is approx. 115 m.
They occasionally race here with Tomos mopeds.

354439354440354441354442354443

OK I see now, I will make an addition.

354445

[Frits Overmars]

Skako, if you rev the engine to its maximum rpm in each gear, you are not using all the available power. If you upshift not at the black, but at the green vertical lines, where the curves intersect, you get the yellow parts of the available power as a bonus.
354447

[skako]

Skako, if you rev the engine to its maximum rpm in each gear, you are not using all the available power. If you upshift not at the black, but at the green vertical lines, where the curves intersect, you get the yellow parts of the available power as a bonus.
354447

I know this because near the end of RPM the difference in available engine power is zero.
The power equalized with all driving resistances (air resistance, rolling resistance).
It is ideal, as you say Frits, to jump into a higher gear just before the end of the RPM at the moment when the power difference becomes equal to the initial power in the higher gear.
In the attached graphs horizontally, from the right curve to the adjacent left curve, you can see how much the RPM drops in a higher gear.
The graph below shows the excess engine power in top gear over the required power at those RPMs.
In the attached graphs, I have drawn the characteristics of three gearboxes.
Standard 5 speed, sport 5 speed, sport 7 speed.
I can only say that this 7-speed sports gearbox is not at all comfortable for everyday traffic around town. It's great when you need to accelerate.
Great traction and acceleration. But when the vehicle in front slows down a bit, you almost regularly have to downshift two gears.
In heavy traffic it becomes very irritating for the driver.
However, on a road with slightly less traffic, it's real enjoyment and melody from a small 50cc engine.

354448354451354450354449354452

Somehow the final speed of 135 km/h in the earlier post seems too optimistic to me. I kind of trust my conservative chart more. It is closer to the reality of the required power and speed of a moped.

354453

[jbiplane]

Hello folks. After some experience with Megasquirt and Speeduino I create my own digital injection and ignition board.
2ign +2inj channels 2layers 36x50mm ECU which consists of 80% components produced in Russia and 20% of Chinese components.
100% local possible but would increase PCBA size to 42x58mm.
The board in next version planned to be a bit smaller and completely integrated into throttle body.
https://reaa.ru/attachments/mikro51x36-jpg.546766/
New version will reworked for other 7.5x7.5mm Russian processor, working at -40...+85C
https://www.zelenograd.ru/img/0/6/5/065c8efb7dafe37e0fd1c8bdcbbc9289.jpg
Rewritting math as well to be suited better for 2-strokes.

[SwePatrick]

A little collage of my injectionbuild.
I actually got it working really good now when changed the fuelstrategy from only tps based, to tps and pipe pressure.
Still based on tps, but fuel compensated against pipe pressure, works really really nice.
In the future i might also compensate ignition some also against pipe pressure.
Look around in my youtube channel, there are video of dynoing all the way to a little mishap(crank seized)
But parts are ordered already =)


https://youtu.be/IGxWVFb-K8M?si=xklrQWUoMa9VLmFO

[ceci]

A little collage of my injectionbuild.
I actually got it working really good now when changed the fuelstrategy from only tps based, to tps and pipe pressure.
Still based on tps, but fuel compensated against pipe pressure, works really really nice.
In the future i might also compensate ignition some also against pipe pressure.
Look around in my youtube channel, there are video of dynoing all the way to a little mishap(crank seized)
But parts are ordered already =)


https://youtu.be/IGxWVFb-K8M?si=xklrQWUoMa9VLmFO

Just a suggestion, have you considered the possibility that a non-mapping injection would be better?

[jbiplane]

A little collage of my injectionbuild.

https://youtu.be/IGxWVFb-K8M?si=xklrQWUoMa9VLmFO

My project is only started and my exhaust system for amateur aircrafts and paramotors rather primitive.
It will be long way to achieve results. May be to the end of the year. But I will try implement all essential ideas.
The problems I encountered to the moment:
- dynamic performance of fuel injectors are complicate and not so primitive like in math of Megasquirt and Speeduino
- software make wrong fuel correction it themperature below -18
- wrong fuel corrections on altitudes more than 2000meters
Will try find couple of good students and give them to implement some math


Just a suggestion, have you considered the possibility that a non-mapping injection would be better?
I open to all ideas. You meant some kind of many dimensional interpolation?
In my first experiences I playing with exhaust gases themperatures making them stable about 650C instead of use Lambda.

[skako]

try to model it in the vehicle performance part of post2t and also show the power range as done in post2t.

I did it with Post2T and it's good that there is a Power Range in Post2T. I transferred the characteristic power points to excel and made my specific diagrams related to the gearbox. In them I can see the same data better. I will try to describe the method through graphs. There are more graphs to explain what they represent and how to read them, but I can only post 6 of them in the post.

354465354464354460354461354462354463

[ceci]

My project is only started and my exhaust system for amateur aircrafts and paramotors rather primitive.
It will be long way to achieve results. May be to the end of the year. But I will try implement all essential ideas.
The problems I encountered to the moment:
- dynamic performance of fuel injectors are complicate and not so primitive like in math of Megasquirt and Speeduino
- software make wrong fuel correction it themperature below -18
- wrong fuel corrections on altitudes more than 2000meters
Will try find couple of good students and give them to implement some math


I open to all ideas. You meant some kind of many dimensional interpolation?
In my first experiences I playing with exhaust gases themperatures making them stable about 650C instead of use Lambda.

Use a method that YAMAHA patented and is now available. It's very simple (if the reeds are curved, the injectors inject)
https://scontent.falc2-2.fna.fbcdn.net/v/t39.30808-6/297962912_6002765133073991_2092138876423286512_n.j pg?_nc_cat=109&ccb=1-7&_nc_sid=c42490&_nc_ohc=JmH33nSrD8cAX8x7X63&_nc_ht=scontent.falc2-2.fna&oh=00_AfBpDzRh0WIPJ6bWQm4ZVrKE3Iu2wcGEHPH4EQdbktT-NQ&oe=65EA6F16

https://scontent.falc2-2.fna.fbcdn.net/v/t39.30808-6/299173756_6018611821489322_5553379824682920918_n.j pg?_nc_cat=104&ccb=1-7&_nc_sid=524774&_nc_ohc=HLk6GjUx_AoAX-6LBDU&_nc_ht=scontent.falc2-2.fna&oh=00_AfAOu_uPwbW2TUFLhhyKdVR7_-rwmm3gHrxO9TSt7lV2_Q&oe=65EBB238

[skako]

Here are three more graphs to complement the explanation in the last post. The engines are adjusted to have the same final vehicle speed that requires the same power. All further comparisons are made from that point.

354466354467354468

[wobbly]

Constantly amazed at learning new stuff every day.
Who would have thought that Yamaha's $300 road bike 1990 TZR250 3XV cylinder was capable of far superior performance than even their super trick rocking horse shit Sugo special 4TW versions worth 500,000 Yen.
The 3XV has 5 " normal " transfer ports that when configured to the Aprilia layout along with the rotary drum PV that closes all 3 Ex ports , it blows the last and best 1999 4DP - 20 out of the water.
This instantly responds to a 75% duct exit , but likes a very different pipe approach - and yes I swallow my narcissist's pride in stating wrongly that convex rear cones dont work.
In this instance to gain some very hard won overev , all hamstrung by the idiot short stroke - the shallower second section helps to the tune of 2 Hp past 12500, looses a little peak - but giving
a much fatter power band where it matters .

[Pursang]

Nice flat torque curve! Be happy to see that in a high performance 4 stroke.

https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=354473&d=1709593432

[jbiplane]

Use a method that YAMAHA patented and is now available. It's very simple
Please give more details what you meant - any link?

[wobbly]

Getting a race 2T to generate a flat torque curve is very much a function of pipe and inlet tuning - all it takes is attention to detail in the results seen in every sim iteration
from EngMod.
Having this in a racebike gives superb " throttle connection " - riders love it when " x " throttle results in "x " power increase over a wide band of torque.
Here is the same result with the CPI 400 Cheetah in a RS250 Cup chassis - it hauls like a train from 8000 out of 2nd gear hairpins and revs hard to 12,000 , blows Superbikes out of the water.
It would be easy to go well over 100RWHp but would then sacrifice all the mid power.

[skako]

Super power band.
The wide power band that is required. Such an engine is easy to drive in city traffic because it has a wide reserve of power under the throttle. The torque characteristic can comfortably satisfy a gearbox with only 4 gears.

[ceci]

Please give more details what you meant - any link?

Tip goes to SwePatrick, who uses a mechanical fuel pump driven by a belt from the TZR250's crankshaft.
The particularity of this system is that it works with variable pressures, in the Aprilia RWS 500 it uses the same pump system (in this one there are no reeds in the intake, since it is by disc, a fuel pressure gauge is used and the CPU needs a mapping with reference to the different "airbox" sensors).
When the intake is by reeds, you do not need a mapping, a fuel gauge, or a pressure sensor in the airbox. Since the injection pressure is given by the rpm and the injection time is given by the reed sensor.
The patent is from Yamaha and it expired years ago.

[ceci]

Please give more details what you meant - any link?

https://worldwide.espacenet.com/patent/search/family/016767083/publication/JP2659564B2?q=JP%202659564%20B2&queryLang=en%3Ade%3Afr



What I propose is to make a transformation of this method, to adapt it to an injection with a mechanical pump (the working pressure is variable depending on the engine speed). How do you know that the reed valve is open and the spray goes to the engine, or on the contrary, the reed valve is closed and what you do is paint the reeds with gasoline?

[Pursang]

..... How do you know that the reed valve is open and the spray goes to the engine, or on the contrary, the reed valve is closed and what you do is paint the reeds with gasoline?

Modern solution (rather than "strain gauges") A coil is laminated into the reed matrix. A stationary magnet is mounted in reed block wall. Movement of reed, in relation to magnet, changes the inductance in the coil.
Simple microprocessor can then determine position of the reed and whether it is opening or closing. Timing and duration of injection can be managed by mapping.
Fuel pressure "bleed off" can also be used for fine tuning things like high speed 'cruise' conditions.

[ceci]

Modern solution (rather than "strain gauges") A coil is laminated into the reed matrix. A stationary magnet is mounted in reed block wall. Movement of reed, in relation to magnet, changes the inductance in the coil.
Simple microprocessor can then determine position of the reed and whether it is opening or closing. Timing and duration of injection can be managed by mapping.
Fuel pressure "bleed off" can also be used for fine tuning things like high speed 'cruise' conditions.

Good solution.
My suggestion is to make the injection as simple as possible, without the need for maps.

[wobbly]

I think trying to create an " analogue " injection system is ignoring the huge advancements we now have in microprocessor speed and reliability.
Sure , modern auto injection systems still use MAP to control regulated fuel pressure , but as you need an ECU to control so many other variables ( everything from ignition to injector PWM to IAT compensation )
is the mechanical system control going to be fast or reliable enough.
Honda spent a huge amount of R&D on a largely mechanically controlled 2T injection system , as the available processors were not fast or sophisticated enough - but abandoned it as it was no better than a normal carburetor
for most of a race lap.
Its only advantage was fuel efficiency ( irrelevant for racing ) - and outright top speed due to the intake geometry.

[ceci]

I think trying to create an " analogue " injection system is ignoring the huge advancements we now have in microprocessor speed and reliability.

The advances are infinite if we compare them with those that had the Motobecane 350 injection

https://www.motobecane-passion.fr/Injection%205b.jpg


Honda spent a huge amount of R&D on a largely mechanically controlled 2T injection system , as the available processors were not fast or sophisticated enough - but abandoned it as it was no better than a normal carburetor
for most of a race lap.
Its only advantage was fuel efficiency ( irrelevant for racing ) - and outright top speed due to the intake geometry.

Honda has done a lot of research on injection in two-stroke engines (in all its forms "direct, pneumatic, indirect") and it is she who is accused of being against 2S.

[TZ350]

354480

Looks like I may have got it wrong again. The tongue on the closing side of the rotary valve is maybe more pronounced then it needed to be. Just a sharp edge or at least a smaller tongue, just enough to stop the RV being pushed into the port when closing. Suzuki GP100 (now 110cc) fitted with the much larger Kawasaki KE175 rotary valve cover.

354481354482354483354484

[TZ350]

354485

The other challenge today has been figuring out how to wire an Ignitec ignition to a power valve actuator. It was very straight forward once I understood what to do.

[wobbly]

TeeZee , I must have explained this a hundred times to many people. The simple way to do PV programming is to disconnect the servo power , and just have the 3 feedback position
wires connected to the ECU. With all the cables positioned and adjusted , wind the servo to the down position till you just feel resistance. Read the position voltage.
Then wind the servo to the full up position - read this voltage on the screen.
Program in the two voltages and the up/down rpm and its done.
Make sure to leave the servo in the down position , turn off the ECU power , reconnect the servo wires.
When you fire up the ECU it will cycle the servo full up , then back down.
If you have the tension and voltages correct you can use 50mV for the hysteresis ( Off ) and around 300mV for the I/P, if its not correct the servo actual Vs servo program box will error in red.

[Frits Overmars]

The advances are infinite if we compare them with those that had the Motobecane 350 injectionI remember that Motobecane approach well. What looks like a harddisk was a transparent disk whose light transmittance was variable over the angular rotation of the disk and over the distance from the light-sensitive cell to the center of the disk, comparable to the read/write head of a real hard disk.
354491354490

Honda has done a lot of research on injection in two-stroke engines (in all its forms "direct, pneumatic, indirect") and it is she who is accused of being against 2S.The Honda technicians were quite inventive. It was the Honda board that was against the two-strokes and therefore blocked several promising developments. ​

[ceci]

The Honda technicians were quite inventive. It was the Honda board that was against the two-strokes and therefore blocked several promising developments. ​

It is fascinating to study Honda's attempts to find a solution to the 2S problems, it has a large number of documents on its pneumatic injection system in English "patents, SAEpapers", best of all it is a 158 page university thesis in JAPANESE . In the thesis, in addition to analyzing their injection system, they analyze the DITECH, making a 250cc prototype with that injection system, to compare with their system on the same mechanical basis.

[porttiming124]

Good morning. I have a question regarding the text that Wayne wrote. (Crap transfers can easily be subjected to "over scavenging " a term coined by Erv Kanemoto about trying fatter pipes on a TZ750 when going from 100 Dia up to 110 Dia.
That is the overly efficient steeper angled diffuser looses more power to short circuiting than it makes power by better scavenging.)
On the dyno if we measure the airflow, will we see the airflow raised and the hp going down in the case of the example of the 110 mm tune pipe in your opinion?

[wobbly]

Yes , the Delivery Ratio may rise due to the more efficient scavenging action of the diffuser , but at the same time the Trapping Efficiency can drop even more - lifting mass airflow , but loosing power.

[porttiming124]

ok thank you

[lodgernz]

354417 354418

Our interpretation of Woblys idea of having the outer edges of the T port the highest.

Not sure if this is correct, Wob and the Dyno will tell us soon enough I guess.

Any progress Rob?

[TZ350]

Any progress Rob?

No, but maybe shortly as we are getting the bikes ready for the dyno before heading down to the GP.

Pinky, the bike with the newly raised eyebrows also has a habit of shaking its cylinder loose. 50% balance factor so not sure what is happening there? Maybe deto as Wob suggested.

[lodgernz]

Wobbly,
a number of times in this forum, you have recommended that when cutting and rotating pipe segments to achieve the appropriate curve, the cuts should be at no more than 7º.

I've been assuming that refers to the actual cut, not the resulting deviation in the pipe, which would be 14º.

Am I correct, or should we be limiting the deviation to 7º, with a 3.5º cut?

[Frits Overmars]

Wobbly,
a number of times in this forum, you have recommended that when cutting and rotating pipe segments to achieve the appropriate curve, the cuts should be at no more than 7º.
I've been assuming that refers to the actual cut, not the resulting deviation in the pipe, which would be 14º.
Am I correct, or should we be limiting the deviation to 7º, with a 3.5º cut?If you want show pipes with a zillion blue-colored 'titanium' welds, go for the smallest angle and the most segments and the most labour.
If you want functional pipes, do not exceed the 7° cut angle that gives you the 14° centerline deviation angle.
A bit of hammering after each weld will yield an acceptable appearance.

[wobbly]

Frits gets the Girl Guide Badge for this weeks reply.

[lodgernz]

If you want show pipes with a zillion blue-colored 'titanium' welds, go for the smallest angle and the most segments and the most labour.
If you want functional pipes, do not exceed the 7° cut angle that gives you the 14° centerline deviation angle.
A bit of hammering after each weld will yield an acceptable appearance.

Thank you Frits and Wobbly.
If you saw my welds, you'd want the fewest possible, to reduce the pain on your eyes.
I usually make the two headers, and sometimes the first diffuser, by hydroforming (all separate), so the cut-and-rotate technique is less required.

[Condyn]

354493

Not an attempt to cut off Frits, as his 7 degree rule is most likely tested and accurate, but I like to use 7.5 degrees as max, simply because thinking about fives and zeros when it comes to angles is easier than fours and eights.

Here is one I recently did that uses 2.5 degree cone ends for a total of 5 degree junctions for the first few sections, then it goes to 5 degree cone ends, and finally 7.5 degree cone ends for the diffuser hook. This keeps the head pipe more straight, and using multiples of 5 keeps things quick and easy for the layout method that I use.

The cheap Cone layout software eliminates the need for cutting and turning, which shortens your pipe and has to be accounted for in the design process. You do need to add the material thickness to your diameters in cone layout as we have found them to be that much smaller after final measurements.

[wobbly]

Seems at odds to me using a superb sim code to design a pipe within 1/10ths of a mm and then hand cut or use crap sheetmetal software to bend the things around the corners.
Using SolidWorks the cut flat laser patterns shapes are perfect as are the finished diameters.
Its easy to define a cone centerline , and sketch in the assembly any contact points such as a frame - plus all the rolled cone section joints are all in line , making assembly easy and repeatable.

The cut angles certainly do make a difference - as I was told to test this in a KZ pipe design process.
I had several cuts at 8* and I had all the seams around the outside of the single main bend - simply making the longer cone joins easier to align dead true.
The request was to reduce the max bend to under 7* ( adding a cut ) and putting the seam on the inside of the 12 cuts.
I did this and back to back it gained 1.5 Hp in 48.

[TZ350]

354417 354418

Our interpretation of Woblys idea of having the outer edges of the T port the highest.

Not sure if this is correct, Wob and the Dyno will tell us soon enough I guess.


Any progress Rob?

Ok, we got it the dyno tonight. Outer edges start opening at 78deg ATDC and the exhaust port is full open at 80deg ATDC.

Made better power than it did before, but we also made some other changes so the results of razing the outer edges of the exhaust port can't be fully credited for the extra power and range. But at least they did not completely kill the engine.

[karter444]

Hi What is it about a 100 cc direct drive reed or rotary kart engines design that allows it to rev to 20,000 quite happily all day .
cheers

[wobbly]

Short stroke , very light reciprocating parts , and a rebuild every hour if you are lucky.

[yatasaki]

Hi What is it about a 100 cc direct drive reed or rotary kart engines design that allows it to rev to 20,000 quite happily all day .
cheers
All day is actually few sec per lap.

[41juergen]

So I would like to get your thoughts on these piston...
It's a TZ250 4DP setup on a street bike with TZ cylinders, heads, pistons and pipes. The engine has the street airbox on it with TMX38 Mikunis. The comp is approx 7.2 with 50% squish and 0,8mm distance. The engine had only 20 km before (incl. a lite acceleration up to 9500 rpm) when seized at approx 6.500 rpm with maybe 1/3 throttle. The engine is on oil pump, the other cylinder is still fine. Exhaust temp at that point was approx 420°C.. The piston has a coating with a piston clearance of 5/100 mm on 100 Octan pump gas. As the engine was running rich on the needle the guy dropped the needle for about 1 notch...
And its not my bike, so don't know more details yet.

[jonny quest]

What brand pistons.

What's different about this engine than a previously reliable engine?

[41juergen]

What brand pistons.

What's different about this engine than a previously reliable engine?

Stock Yamaha TZ pistons, the only change was the drop of the needle for 1 notch (and the engine was running rich before)...

[yatasaki]

Stock Yamaha TZ pistons, the only change was the drop of the needle for 1 notch (and the engine was running rich before)...

That carbon deposit tells me that squish gap is too tight

[F5 Dave]

I'd be checking oil feed to that cylinder. That's ugly.

[wobbly]

Has it got an Ignitech with 28* advance flat line out to about 8000, things seize when run at part throttle for any time doing this.
And due to the big differences in case volume and intake length the 3XV/3YL/4DP always lock up one side well before the other.
Running the Ignitech on a 4DP I ended up with 2* advance split on the LH cylinder - this gave almost dead equal jetting and equal egt.

[philou]

the needle profile is not good.
often the case on Mikuni carburetors.
use a needle jet calculator which gives you the distribution curve.

[41juergen]

So it looks like that the coating was done not proberly, the piston what seizured was too large, the piston clearance was only 0.035 mm... the onyl question remains for me why the engine didn't seizured already during the first 20 km..

[philou]

the condition of the piston crown is not due to lack of clearance

[jbiplane]

I use manual decompression valves to facilate start of 2-stroke engine with electrical starter.
But pilots of paramotors want start-stop engine in a flight. Stop when flying in thermic and launch if dont sucseed.
I saw on husqvarna chainsaws automatic decompression valves which actuated by pressure variation in crancase.
https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSivS6DwSoIZzFtGod_iqjLi-7ZRdcFbAvTYueckSavsjGCy7mAPo-TTnhIwV5_w5buNss&usqp=CAU
Claimed non-reliable and in my case useless cause 534gramm LiPo battery cannot make even first turn.
Manual actuation a bit pervert. For me decompressor which always open after 10 seconds of engine stops could be a solution.
To actuate manual valve enough 600gramm pressure and 5mm movement.
Any suggestion-solutions? Preferable simple addon to chainsaw decompression valve.
Thinked even of solenoidal electrical actuator...
But better automatic mechanical simple. Actuated after engine stops.
https://ae01.alicdn.com/kf/H310ea778919a4377b0c96d13c0d8ba6b8.jpg_640x640Q90. jpg_.webp

[diesel pig]

I use manual decompression valves to facilate start of 2-stroke engine with electrical starter.
But pilots of paramotors want start-stop engine in a flight. Stop when flying in thermic and launch if dont sucseed.
I saw on husqvarna chainsaws automatic decompression valves which actuated by pressure variation in crancase.
https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSivS6DwSoIZzFtGod_iqjLi-7ZRdcFbAvTYueckSavsjGCy7mAPo-TTnhIwV5_w5buNss&usqp=CAU
Claimed non-reliable and in my case useless cause 534gramm LiPo battery cannot make even first turn.
Manual actuation a bit pervert. For me decompressor which always open after 10 seconds of engine stops could be a solution.
To actuate manual valve enough 600gramm pressure and 5mm movement.
Any suggestion-solutions? Preferable simple addon to chainsaw decompression valve.
Thinked even of solenoidal electrical actuator...
But better automatic mechanical simple. Actuated after engine stops.
https://ae01.alicdn.com/kf/H310ea778919a4377b0c96d13c0d8ba6b8.jpg_640x640Q90. jpg_.webp

You need a victer automatic lawnmower 2-stroke decompressior. works great on my Husqvarna motorcycle engine.

[teriks]

Hi, trying something different than those 6.6cc glow plug engines..

Does someone by chance have ENGMOD model of a AS3/TA125/RD125 twin to share or even sell?
Very old stuff so I strongly doubt that, but unless you ask...

Got myself an AS3, first intention was to keep stock and just enjoy, but.. well that failed.
First thing fitted is an Ignitech, what a luxury to have direct control over ignition timing!
I'm fortunate enough to have two spare sets of cylinders + heads so some work on those and pipes are in the (very long term) plan.

Not that it will ever be a super powerful racer being air-cooled with super crappy transfers due to cylinder spacing, but that may be a good thing.
-Those drum brakes are not very impressive either, not to mention the handling, but I get to enjoy the lovely sound of a two stroke twin. :)

[pete376403]

You need a victer automatic lawnmower 2-stroke decompressior. works great on my Husqvarna motorcycle engine.

https://sesdirect.co.nz/collections/walk-behind-mower-parts-victa/products/genuine-victa-decompressor-en72541p-complete-short-body-1

[diesel pig]

https://sesdirect.co.nz/collections/walk-behind-mower-parts-victa/products/genuine-victa-decompressor-en72541p-complete-short-body-1

I found the long body fitted better on my Husqvarna bike but each to there own.

[TZ350]

.
354510

Looks like the piston has been tapping the insert. Skimmed about 0.004" of the face of the squish.

354509

Pleased to see the plug thread cooling fins look like they have had water passing between them.

[pete376403]

I found the long body fitted better on my Husqvarna bike but each to there own.It was more to dirt jbiplane towards Victa mowers, which may be uncommon in Russia

[Niels Abildgaard]

https://sesdirect.co.nz/collections/walk-behind-mower-parts-victa/products/genuine-victa-decompressor-en72541p-complete-short-body-1

How does it work and how many seconds to open again after a failed try?

[diesel pig]

How does it work and how many seconds to open again after a failed try?

the black plastic fitting on top of it is for a vacuum line and work's like a vacuum operated fuel tap but the other way around no vacuum(motor not running) it's open and no compression. Vacuum (motor running) it's closed and has compression.

[Niels Abildgaard]

the black plastic fitting on top of it is for a vacuum line and work's like a vacuum operated fuel tap but the other way around no vacuum(motor not running) it's open and no compression. Vacuum (motor running) it's closed and has compression.

Thank You for explanation of the obvious.
Way smarter than using compression through a one way valve.

[Frits Overmars]

the black plastic fitting on top of it is for a vacuum line and work's like a vacuum operated fuel tap but the other way around no vacuum(motor not running) it's open and no compression. Vacuum (motor running) it's closed and has compression.So when the engine is not running, the valve is open. Then how do you generate enough vacuum to close the valve?

[jato]

Even though those Victas were australian they were keen to work ... so partial compression was enough for them to start and once running the small volume on one side of the diaphragm had its pressure drawn down by the vacuum line going to the downstream side of its (quite small) carb

[Niels Abildgaard]

So when the engine is not running, the valve is open. Then how do you generate enough vacuum to close the valve?
For the benefit of all mankind:
Can someone from down under, make or point to a video showing start of a Victa lawn mower?

[jato]

The girlfriend has offered to start the lawnmower here but i don't know how to work the video recorder ... sorry mankind

[diesel pig]

So when the engine is not running, the valve is open. Then how do you generate enough vacuum to close the valve?

The valve is tiny, so if you turn over the motor fast enough (like when you kickstart a dirt bike) all the air in the cylinder can't get out of the cylinder before it sparks. So it does have some compression but more like if you left out the compression ring when rebuilding a motor. It makes starting big bore 2 strokes easy.

[diesel pig]

For the benefit of all mankind:
Can someone from down under, make or point to a video showing start of a Victa lawn mower?

Amazing enough there is web site that has old Victa 2 stroke mowers on it. I saw it when setting up my Husqarna. Husaberg it's your time to shine!

[diesel pig]

Even though those Victas were australian they were keen to work ... so partial compression was enough for them to start and once running the small volume on one side of the diaphragm had its pressure drawn down by the vacuum line going to the downstream side of its (quite small) carb

How embarrassing, I was so busy tapping out a reply I didn't see your better reply.

[Pursang]

I've got a 500 Maico Enduro in the workshop. The decompressor for those is a manual valve about 1/2 way up the back wall of the cylinder, rather than in the head.
So it's more like starting a 300 rather than the full 490cc. Once started, it will run happily, but noisily, with the valve held open.

[jbiplane]

Thank all peoples for decompresion valve ideas!!!
I own 8 CNC machines and will try make automatic decompression valve.
For me easier make than buy.

[lodgernz]

Thank all peoples for decompresion valve ideas!!!
I own 8 CNC machines and will try make automatic decompression valve.
For me easier make than buy.

One can never have too many CNC machines

[aljaxon]

354493

Not an attempt to cut off Frits, as his 7 degree rule is most likely tested and accurate, but I like to use 7.5 degrees as max, simply because thinking about fives and zeros when it comes to angles is easier than fours and eights.

Here is one I recently did that uses 2.5 degree cone ends for a total of 5 degree junctions for the first few sections, then it goes to 5 degree cone ends, and finally 7.5 degree cone ends for the diffuser hook. This keeps the head pipe more straight, and using multiples of 5 keeps things quick and easy for the layout method that I use.

The cheap Cone layout software eliminates the need for cutting and turning, which shortens your pipe and has to be accounted for in the design process. You do need to add the material thickness to your diameters in cone layout as we have found them to be that much smaller after final measurements.

that cone program is excellent but as you say gives you dimensions for the centre of the material used. so the thickness needs adding on to the diameters. using that software and autocad to draw the centre line of the header to work out the angles to fit the bike i dont have to adjust or pie cut any of the metal cones. i used to make card templates and adjust the angles . much easier to print out a modded dxf file and cut the card. and then adjust to get the right fit. then once worked out its a simple case of sending the dxf files to the laser cutter all dims to 1/10th of a mm. works for me. now i dont even need to make the card cones. i just put an exit angle of 5 degrees on each cone and that gives you a bit of leeway. i even fiddle the phi figure to get the seams out of view and it looks like you have done that too condyn. if you arent bothered about visible seams then a 5 degree exit and entry to each section on that cone program virtually eliminates the need for any pie cuts. its all in the planning.



just made some 19mm rollers so as to be able to roll my 25-30mm diam header sections. ive always had to bend them around tubing and it took a while matching up the seams of each section.
i was looking forward to making one of those pipes with zillion blue-colored 'titanium' welds, going for the smallest angle and the most segments and the most labour. as per frits comment.
(although mine are in mild steel.)
wont go that far but i want to have less of the spiders legs look to the headers.

a pal has just ordered the mota8 upgrade and well have a bash using that. does it allow for incorporating a wobbly duct?

we've made good cruising pipes using wobblys suggested percentages. including a flukey fat pipe that does everything. now to make widish powerband pipes suitable for 4 wide spaced gears. 7-11k and 9-13k,

[wobbly]

Here is the latest 4DP racebike pipes cut up in SolidWorks such that the 3D bends all have the cut seams in line - means the pipe can be assembled without the bike or a jig except for the rear mounting.

[wobbly]

Mota doesnt know who Wobbly is , but you can enter the " correct" duct exit into the input and it wont have any idea what you have done.

[Javier Ruda]

I’m using Janbros spreadsheet for calculating STAs and having a good match between transfer and blowdown.

For the auxiliary exhausts, which horizontal angle should I use?

It’s like a 90° turn from cylinder wall to auxiliary duct. Should 45° be ok for the calculation?

[wobbly]

The axial down angle of the Main and Aux affects the effective area value due to the Cosine.
But horizontally you simply enter the actual flow width , not the Chordal at the bore face.
I dont use JanBro's spreadsheet , but that is how its normally done.

[Javier Ruda]

Thank you wobbly, I will use the section of the duct, and forget about the port area.

[wobbly]

You have to be careful though with the Aux flow. Much of the bulk flow occurs close to the port opening width , due to the high pressure ratio across the port at that timing.
With very well designed triangular shaped Auxiliary ports the actual effective area is a combination of the chordal area at port opening , and the duct area behind the port.
So to represent reality both must be taken into account - as does EngMod , but I don't know about a spreadsheet based calculator.

[Javier Ruda]

I understand, it is too complex for a spreadsheet.

I will do an assumption considering that the original Rotax 122 had matching numbers for blowdown and transfer. So I could use the auxiliary duct angles used in the spreadsheet that fulfil that assumption. The shape of the new duct is very similar, just only a bit wider and taller to be 5° below exhaust opening. For the port window, I didn’t dare to do it very triangular, just only flat and slightly wider at the top.

[skako]

Hi,
which is the optimal duration of measurement on the dyno desk (it is related to the inertia of the dyno), for the engine to reach from 2/3 RPM to max. power RPM.

[wobbly]

The inertia and the gearing should be such that you can do three back to back WOT runs and the egt does not change at the end of each pull.
Not enough inertia , or too short gearing , and the pipe heat will increase more , as you repeat the runs.
Of course you need sufficient airflow to get repeatability as well.

[skako]

The inertia and the gearing should be such that you can do three back to back WOT runs and the egt does not change at the end of each pull.
Not enough inertia , or too short gearing , and the pipe heat will increase more , as you repeat the runs.
Of course you need sufficient airflow to get repeatability as well.

I'm interested in what time interval it is most often, 5, 10, 20 seconds, so that I don't take too much inertia of the flywheel for my needs.
I also have to pay attention to the max. allowed RPM for the flywheel so that a possible accident does not occur.

[wobbly]

My engine dyno for 50Hp KZ engines takes 12 seconds from 9000 to 15000 WOT.

[skako]

Thanks wobbly for the info.

[F5 Dave]

12 seconds in one gear? They will never do that in real life except at Bonneville surely? Assuming they have a go-kart class.

[wobbly]

That is the acceleration rate in 6th gear for a KZ , if the run time is any shorter , the pipe does not heat up sufficiently to get repeatable results.
With the jet setup we use , the egt has hit around 520*C ( with WOT from about 8000 ) at 9000 where I start recording ,and if the main is correct for the weather it will hit 620*C by the end of the pull.
And as I said I can do 3 back to back and get the same final egt.
These numbers are also exactly what we see on the data , pulling out of a second gear corner at about 9000 , and in 6th down the shute pulling 14800.
If you dont have this scenario it gives rise to the issue that has plagued dyno operators forever " you cant run the same jetting on the dyno as at the track".
This is BS if the inertia/gearing/run time is correct.
In roadracing with a KZ ( close to a LSR run ) we can happily jet up over 650*C because the run time between peak torque and peak Hp is so short , and overev is used most of the time.

[F5 Dave]

Ah. Are KZs run on full tracks? I'm stuck thinking go-kart tracks with 30second lap times.

[wobbly]

Hamilton kart track has a mid 40s lap time and we pull 145Km/h on a good day.
Road racing on full circuits is a whole different class of racing.

[F5 Dave]

I've raced about ten kart tracks in NZ, but never been to Hamilton. Two wheels only.

[lodgernz]

I've raced about ten kart tracks in NZ, but never been to Hamilton. Two wheels only.

Andrew Stroud tried to get us in there. Not a chance.

[Peljhan]

We raced with 50cc on Grobnik Rijeka circuit in Croatia, and accelerations were like 30s long and we have 80% of the lap full throttle. Sometimes there is really strong head wind and I needed to shift from 5th to 4th on a straight because I only had 14hp. It is very different kind of racing compared to gokart tracks and I been with my bike on both.
https://www.youtube.com/watch?v=N2Trr21edn4&t=5s

[yatasaki]

14 hp is excellent actually

[TZ350]

354568 354569 354570

Started digging out the eyebrow exhaust ports for the 250cc F81M pre 72 post classic racer.

Best run ever was 42 RWHP at 9,500 rpm with the single exhaust port version. It will be interesting to see if the eyebrows make a positive improvement. It could go either way.

[F5 Dave]

Rob that main port needs way more chamfer.

[TZ350]

Rob that main port needs way more chamfer.

Not finished yet, still more work to do. Main Ex timing needs to be opened up and port widened to get the needed STA.

I just had to show off my eyebrow tunneling. Did not think it could be done nicely, but it looks like it is going to work out Ok.

Speedpro helped a lot by making the initial eyebrow cut with his mill.

[SwePatrick]

Watch my space on the tube the coming days/weeks.
https://www.youtube.com/channel/UClYLnCM69NLN9TGXDqxr0EQ

I have updated my TZR250 (1KT) engine and will be searching for new higher numbers.
Longer rods with uprated bearings.
Reshaped crankhouse(welded and ported)
Reshaped heads for more possibilities to rev higher.
Larger injectors, might run methanol in the future.
Slightly increased timings
And ofcourse refurbishing, new bearings and new pistons.


354571

[SwePatrick]

Assemble video out now!


https://youtu.be/Xsxlnz9GDxw?si=pLIZ5EhVaGuHeOig

[JanBros]

"very small amount" (of sealant on the crankcase)
@6:28

that is a lot of sealant :confused:
I only ever use so litlle, that I can still see the colour of the material under the sealant.

[speedpro]

I couldn't see what sealant you were using but I've experienced issues with using the incorrect sealant where it is contacted by fuel. I now use ThreeBond 1104 NEO plus. The spec sheet says it is suitable for use on fuel pump flanges. So far no problems. I got onto it after bumping into an ex ThreeBond employee at the supplier.

[TZ350]

.
<iframe width="560" height="315" src="https://www.youtube.com/embed/9mJNE0fJUBM?si=yAExHT4SNX6alSrR" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen=""></iframe>

150cc two strokes. Might be time to look at a F4 rule change to allow us two strokers to be able access more modern engines and regain some competitiveness with the fast four stroke guys.

[aljaxon]

Mota doesnt know who Wobbly is , but you can enter the " correct" duct exit into the input and it wont have any idea what you have done.


i wish i was able to use solidworks. ive only just took the time to learn how to use autocad on a basic level.
i saw this video


https://www.youtube.com/watch?v=qyazo-LOung

around the 2min 30 mark he uses mota8 to do an optimisation of the pipe. dunno if its able to do that with any accuracy or if its just a gimmick. i guess we will find out soon enough. the video maker says engmod2t is far superior in every way to mota8 but he was intrigued by the pipe optimisation feature.

[lodgernz]

.
<iframe width="560" height="315" src="https://www.youtube.com/embed/9mJNE0fJUBM?si=yAExHT4SNX6alSrR" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen=""></iframe>

150cc two strokes. Might be time to look at a F4 rule change to allow us two strokers to be able access more modern engines and regain some competitiveness with the fast four stroke guys.

Either that, or stop the 4-stroke cheating.

[wobbly]

Only issue with the 150 class in Asia is that every single fast bike is a KR - but knowing you guys any combination of parts is possibly better.

Im doing a racebike engine project and need a 350YPVS cylinder / piston just to measure up. Anyone got one I could beg/borrow/steal for a day.

[porttiming124]

Hello everyone. I do dyno (snowmobile engine) in my personal garage.
I want to reduce engine noise in the garage because even though I have a big truck muffler outside. I realize that the noise is coming from inside the garage.
So to reduce the noise I thought of making a long silencer for each pipe with a length of approximately 900mm ( I know it's long but it's a brain storm) with an internal diameter of 38mm. Connect directly to the end of each tune pipe. At the exit of this long silence the exhaust would be sucked in by the large 8 inch pipes of the blower. My biggest fear and my question.
Will this long muffler extension with a diameter of 38mm change the tuning in your opinion?354584
Do you have a better idea?

[F5 Dave]

Either that, or stop the 4-stroke cheating.
I'm told there are lots of rumours of 180 kits. Bizarre if true.

[F5 Dave]

Only issue with the 150 class in Asia is that every single fast bike is a KR - but knowing you guys any combination of parts is possibly better.

Im doing a racebike engine project and need a 350YPVS cylinder / piston just to measure up. Anyone got one I could beg/borrow/steal for a day.
Let's us know how you get on. All I've got is over sized ported barrels with wiseco.

[lodgernz]

I'm told there are lots of rumours of 180 kits. Bizarre if true.

177cc is common (67mm piston), but there are kits from Malaysia up to 210cc. These require moving the cam drive, so can be recognised if you know how.
I'm told that kits can be had for the Yamaha R15 up to 230cc, which are indistinguishable from the stock cylinder..
Certaily not good for the sport, but some people just have to compensate for their lack of talent with lack of integrity.

[speedpro]

It's a decent size industry in places like Malaysia and Taiwan. My Yamaha 125cc scooter is 229cc built with high quality inexpensive parts from Taiwan. They go to over 300cc but that's getting pretty serious with welding and machining.

[Grumph]

177cc is common (67mm piston), but there are kits from Malaysia up to 210cc. These require moving the cam drive, so can be recognised if you know how.
I'm told that kits can be had for the Yamaha R15 up to 230cc, which are indistinguishable from the stock cylinder..
Certaily not good for the sport, but some people just have to compensate for their lack of talent with lack of integrity.

My experience with Formula Fords suggests the cheaters simply move from the rear of the pack to the middle...

If there's enough worry about cheaters, pull a couple of bikes down at random - after warning them it's coming.

[lodgernz]

My experience with Formula Fords suggests the cheaters simply move from the rear of the pack to the middle...

If there's enough worry about cheaters, pull a couple of bikes down at random - after warning them it's coming.

MNZ has bought one of these:
354585

Goes down a 12mm plug hole and logs the bore measurement. Only works for central plugs unfortunately, and the R15 is angled.

[F5 Dave]

They used to file the GP winners top 3 into an aircraft hanger for strip down. Of course there were no fourstroke bikes in that mix back then until one of the sherrifs boys (Chris I imagine) won on a feelthy honda.

[Vannik]

Hello everyone. I do dyno (snowmobile engine) in my personal garage.
I want to reduce engine noise in the garage because even though I have a big truck muffler outside. I realize that the noise is coming from inside the garage.



A large percentage of the noise is generated by the inlet. Way more difficult to silence without creating a restriction. What do you do for intake silencing?

[Pursang]

A large percentage of the noise is generated by the inlet. Way more difficult to silence without creating a restriction. What do you do for intake silencing?

Connect the Inlet to the Exhaust. Won't help with power.....but it will stop the noise!

[porttiming124]

A large percentage of the noise is generated by the inlet. Way more difficult to silence without creating a restriction. What do you do for intake silencing?

Hello Neels.
Before I had nothing in front of the carburetors.
Last week I made myself a lexan box for 3 reasons.
-the noise
-always breathe in fresh air.
-calculate cfm with the air meter.
But I admit that I have doubts about the tuning.354586

[Haufen]

.
<iframe width="560" height="315" src="https://www.youtube.com/embed/9mJNE0fJUBM?si=yAExHT4SNX6alSrR" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen=""></iframe>

150cc two strokes. Might be time to look at a F4 rule change to allow us two strokers to be able access more modern engines and regain some competitiveness with the fast four stroke guys.

I would love to see a typical power curve of those bikes. Has anyone seen something by chance?

And does anyone happen have to a KR150 EngMod Pack file they would share?

[Vannik]

Hello Neels.
Before I had nothing in front of the carburetors.
Last week I made myself a lexan box for 3 reasons.
-the noise
-always breathe in fresh air.
-calculate cfm with the air meter.
But I admit that I have doubts about the tuning.

That should help but the flat sides of the box will still transmit a fair amount of the noise. Can you add stiffeners to the outside? Just thinking.

Nice looking set of pipes!

[porttiming124]

Good idea, I'll try to stiffen the flat sides.
Thanks for the pipes.

[SwePatrick]

New release of my TZR/TZ project:


https://youtu.be/uC_ur-w1HvM?si=MvU_0m9NwTSsEGDZ

[Tim Ey]

Does anyone know how many amps the Ignitech DC CDI P2 Race is able to shift with the Multifunction outputs? Will 0.85A at 13 Volt (11W) work?
BR
Tim

[wobbly]

The Ignitech P2 Race manual says " Outputs can switch resistive or inductive load up to 2 A ".

[wobbly]

I want to add some epoxy to the front B port wall to make it perpendicular to the bore like the Aprilia scavenging regime.
So I have taken silicon port cores , and will cut these to use as forms.
The only epoxy I have ever used is JB Weld or Devcon F putty. Both are way to viscous to be able to "pour " it down between the duct wall and the form wall - even if the casting
is sat in an oven for a while , they will soften but go off with the heat before filling the vertical void completely.
Any suggestions on what to use in this scenario that WONT fall out.

[lodgernz]

I want to add some epoxy to the front B port wall to make it perpendicular to the bore like the Aprilia scavenging regime.
So I have taken silicon port cores , and will cut these to use as forms.
The only epoxy I have ever used is JB Weld or Devcon F putty. Both are way to viscous to be able to "pour " it down between the duct wall and the form wall - even if the casting
is sat in an oven for a while , they will soften but go off with the heat before filling the vertical void completely.
Any suggestions on what to use in this scenario that WONT fall out.

Devcon B putty is more liquid, so you can orient the cylinder to the angles you want, then pour it in and it settles at those angles It's still pretty viscous, but it does eventually settle.
Type B is a bit hard to find in NZ though.

[Javier Ruda]

I want to add some epoxy to the front B port wall to make it perpendicular to the bore like the Aprilia scavenging regime.
So I have taken silicon port cores , and will cut these to use as forms.
The only epoxy I have ever used is JB Weld or Devcon F putty. Both are way to viscous to be able to "pour " it down between the duct wall and the form wall - even if the casting
is sat in an oven for a while , they will soften but go off with the heat before filling the vertical void completely.
Any suggestions on what to use in this scenario that WONT fall out.

Hello Wobbly, a did it recently, for changing the roof angles and the B front wall angle. I used JB Weld and as you mentioned it will not pour by gravity.
What I did is to add some tape at the transfer exit and also the entry, for doing a kind of basin. Then I filled the basin with the help of a long enough stick, and tried to make it as flat as possible while keeping the cylinder vertical (exhaust down, intake up). Once cured, I adjusted the shape retiring the excess epoxy with a rotary tool.

All very very time consuming, specially the roof angles.

[TZ350]

.

Rebored the cylinder and chamfered the ports before gluing up the transfer porting mistakes, actually over cutting the transfers and then gluing them back up turns out to be a real easy way to get a smooth symmetrical port. I had mistakenly cut the ports so they opened 110deg ATDC when I really wanted 116.

Now I have a really good experimental barrel. So I degreed up the motor again at 116 ATDC and measured how far down the cylinder the piston was and cut a piece of plastic pipe that length. Covered it in plastic wrap and inserted it into the cylinder. Now the glued transfer ports will all be exactly the same height, timing and match each other.

I warmed the cylinder with a heat gun and when the Devcon F glue was put in the warm transfer port it ran freely like water and leveled out very nicely. By gluing a port in three stages I could get a very nice curve to the transfer roof. I made the rear ports flat and the main ports angle up at 29degrees.

The great thing about this gluing thing is that its so easy to change. When I finally get the scavenge pattern that I want I will be able to make a permanent copy with a new cylinder.

Pic-1 setting the angle of the port
Pic-2 warming the cylinder
Pic-3 gluing the port, doing this in three stages makes for a nice curved port roof
Pic-4 glued ports and the plastic former

.

354594354595354596354593


Hello Wobbly, a did it recently, for changing the roof angles and the B front wall angle. I used JB Weld and as you mentioned it will not pout by gravity. All very very time consuming, specially the roof angles.

Time consuming alright. You might find JB weld pours easier and smooths out nicely in a warm cylinder. We never had any problems with JB weld coming loose in the ports.

[TZ350]

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

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

230863

The oiler holes for the exhaust bridge need plugging.

230864

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

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

So the were prept up with a dremmil.

230866

And the finished result.

230865

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

230862

The Ex/Trans bridge

354597354598

We used Belzona for sealing the bridge oiling holes but I suspect you could use JB weld here too.

[TZ350]

.
Using "Thread Tools" at the top right of the page you can find all the images on this thread and look through them. Plenty of interesting stuff there.

[Condyn]

Wobbly, not sure if you have enough room in the “crevice” between the cut core and the B wall for this, but I have recently used small ID hard plastic air brake line and a ram rod to push devcon into a narrow/deep water jacket. It worked but it was not simple as the devcon pushes hard. 354599

[136kg136ps]

Wob, JB weld is viscous enough to inject with a sturdy syringe. I have had to soak the tubes in hot water on colder days to get it thin enough. I use one similar to this. A small greasegun would likely be suitable as well.

[jfn2]

Hello 136kg136ps
How do you clean the syringe after your done using it? Where do you get a setup like this? Nice idea!

[yatasaki]

I agree for belzona 1111, there is one even better and more liquid ,belzona 1391T. You can even heat it up to pourbetter . It's a coating, not filler but works well and should stand 250°C

[136kg136ps]

Hello 136kg136ps
How do you clean the syringe after your done using it? Where do you get a setup like this? Nice idea!

Pretty much disposable one time use sadly. I tried acetone, spirits, alcohol, tolulene, xylene.
The good news is that they are relatively inexpensive.
I get them at Walmart, but the internet is full of them from about $10 USD.

[wobbly]

I can get Devcon B liquid out of Australia ( made there ) for near 1/2 what retailers sell it for here.
The syringe with that would be super clean and tidy even if it is " disposable".
Come to think about it , the liquid version would be easily dispensed with a heavy duty plastic syringe I imagine.

[pirkka1]

I want to add some epoxy to the front B port wall to make it perpendicular to the bore like the Aprilia scavenging regime.
So I have taken silicon port cores , and will cut these to use as forms.
The only epoxy I have ever used is JB Weld or Devcon F putty. Both are way to viscous to be able to "pour " it down between the duct wall and the form wall - even if the casting
is sat in an oven for a while , they will soften but go off with the heat before filling the vertical void completely.
Any suggestions on what to use in this scenario that WONT fall out.
Greetings from Finland, first post here.
I thought i'd share my experiences. Husqvarna sm 125 7 transfer converted to 5 transfers. I used Bison Metal epoxy(looks like its only available in europe) but it was very easy to pour when heated a little bit.
has been holding up for three years of occasional racing without even trying to come off.
354604354605354606354607

[wobbly]

Thanks guys , I have some Devcon B coming from OZ and i got some big plastic syringes for $4.00 , perfect.
Just have to mask the port and duct entry then use a bubble level on the cylinder for the liquid to form a dead flat new wall - easy.

[Tim Ey]

Greetings from Finland, first post here.
I thought i'd share my experiences. Husqvarna sm 125 7 transfer converted to 5 transfers.
...and? Did the changing of the porting scheme do you good? Measurable improvement?

[wobbly]

Well as an example of what can be done, here is a 4DP20 Kit cylinder that is close to rocking horse shit and moon beam cost ( 500,000Yen ) that has 7 transfers and the
best pipe money can buy - the latest Jolly/JL for a 4TW.
Against a 3XV - TZR250 road bike cylinder with a PV that closes off all 3 Exhausts and its 5 transfers ported as per the RSA scavenging scheme , plus of course my 75% duct exit area ( stock 3XV ).

They both achieve exactly what the port STA numbers say is possible , but are of course hamstrung inherently by Yamaha's obsession with the short 50.7 stroke and
wanting insane amounts of transfer port duct wall area.
They won nothing for 10 years with the 3YL/4DP due to this shortsightedness till 2000 with the NX5 that was square and won the 250GP title easily with Olivier Jaques.

You can also see that Yamaha were obsessed with huge reeds ,Im thinking of fitting RS125 VeeForce that are smaller in curtain area , but make more power in the sim - funny that.
Also allows me to make the manifolds the same , stock , one is 20mm long , the other is 40mm - plain dumb.
Might even go Lectron with the Yamaha solenoid powerjets as this allows both inlets to be dead straight, as the Mikuni's cant be tipped up as much - worth 1.5 Hp in a SKUSA CR125.

[pirkka1]

...and? Did the changing of the porting scheme do you good? Measurable improvement?

Kinda testing in progress and a really bad test at that.I changed too many things at once. the stock cylinder only has 117 transfer and 177exh timing. mine were raised to 130/200 with the 5 transfer mod.
With 36mm pwk,modified stock inlet and factory CR cross pipe it made 28.2whp at 12000rpm with too low egt. driving it power fell off only after 13k and ran 13.5k when doing top speed.

my friend has pretty much the same setup with small differences like 38mm TMX, Vforce3 and Rino tuning exhaust, about same timings and ported by me, but still 7 transfers. and it 27.5whp and less low end and over rev. both bikes have ignitech igniton.

Cant really say the 5 transfer mod is making the difference due to different setups. next plan is making a new exhaust to make some of the port area i have and see how well(or badly) the scavenging holds up.

[F5 Dave]

That seems somewhat confused. What are you trying to build? At those revs, not an mx bike, some sort of Motatd hybrid? Enormous change in timing and presumably an mx pipe fitted still.

[41juergen]

Well as an example of what can be done, here is a 4DP20 Kit cylinder that is close to rocking horse shit and moon beam cost ( 500,000Yen ) that has 7 transfers and the
best pipe money can buy - the latest Jolly/JL for a 4TW.
Against a 3XV - TZR250 road bike cylinder with a PV that closes off all 3 Exhausts and its 5 transfers ported as per the RSA scavenging scheme , plus of course my 75% duct exit area ( stock 3XV ).

They both achieve exactly what the port STA numbers say is possible , but are of course hamstrung inherently by Yamaha's obsession with the short 50.7 stroke and
wanting insane amounts of transfer port duct wall area.
They won nothing for 10 years with the 3YL/4DP due to this shortsightedness till 2000 with the NX5 that was square and won the 250GP title easily with Olivier Jaques.

You can also see that Yamaha were obsessed with huge reeds ,Im thinking of fitting RS125 VeeForce that are smaller in curtain area , but make more power in the sim - funny that.
Also allows me to make the manifolds the same , stock , one is 20mm long , the other is 40mm - plain dumb.
Might even go Lectron with the Yamaha solenoid powerjets as this allows both inlets to be dead straight, as the Mikuni's cant be tipped up as much - worth 1.5 Hp in a SKUSA CR125.

Not more to say... :niceone:

[Orengo98]

A bit of a stupid question maybe, but...

I'm currently working on a bike, and I need to buy the spark plugs for it. The manual recommends a Lodge R47-49, Champion L58R or a Bosch W290 - t16 and the bike arrived to me with a Champion L-3G.

The thing is that all of those are short reach plugs, and the cylinder head seems to have been designed for a long reach spark plug. If I install any of those plugs, the spark plug remains "hidden" inside the thread hole of the cylinder head. And that doesn't look good to me.

354634

Would you agree it's better to ignore the manual and fit a long reach plug? If I install a long reach plug with a washer, the plug is flush with the combustion chamber roof.

Thanks in advance!

[Frits Overmars]

I'm currently working on a bike, and I need to buy the spark plugs for it. The manual recommends a Lodge R47-49, Champion L58R or a Bosch W290 - t16 and the bike arrived to me with a Champion L-3G.
The thing is that all of those are short reach plugs, and the cylinder head seems to have been designed for a long reach spark plug. If I install any of those plugs, the spark plug remains "hidden" inside the thread hole of the cylinder head. And that doesn't look good to me.
354634
Would you agree it's better to ignore the manual and fit a long reach plug? If I install a long reach plug with a washer, the plug is flush with the combustion chamber roof.A Bultaco head, isn't it? All Bultacos I've worked on had long reach spark plugs so I wonder what type yours is.
Anyway, never fit a short reach plug in a long reach head or vice versa. And if your head was modified from a short to a long reach plug, chances are that it was not the only modification, so you may forget about the manual in this respect.

[pirkka1]

That seems somewhat confused. What are you trying to build? At those revs, not an mx bike, some sort of Motatd hybrid? Enormous change in timing and presumably an mx pipe fitted still.

the stock timings are for 11kw regulations. the motocross version of the bike has typical 128/190 timings. Im just tuning it fun and seeing how much power i can get out of it.
the mx pipe is just what i had laying around, i know it need a better pipe.

[F5 Dave]

Oh. So it's road legal base. Didn't understand that as we don't have such draconian license laws. And you mentioned racing somewhere I think.

You could ride a full power RGV250 when they came out. That got dialled back to power to weight so a restricted 660 Triple is OK or a full (lack of) power 250 4 stroke.

Been a while since I was concerned of such things.

Heck my GG300 came with a spare road legal pipe. I fitted it for a dirt ride as it looked pretty much identical except that it hadn't been munched on a rock step. And it was matt black not Nickel.

It ran like a 3 legged cow. Turns out there was a Cat buried in the depths of the dwell section.

[diesel pig]

Well as an example of what can be done, here is a 4DP20 Kit cylinder that is close to rocking horse shit and moon beam cost ( 500,000Yen ) that has 7 transfers and the
best pipe money can buy - the latest Jolly/JL for a 4TW.
Against a 3XV - TZR250 road bike cylinder with a PV that closes off all 3 Exhausts and its 5 transfers ported as per the RSA scavenging scheme , plus of course my 75% duct exit area ( stock 3XV ).

Are the 3XV cylinders so much better than the 3MA cylinders. Would the 3XV cylinders still be better than the 3MA cylinders after they are ported? Just trying to work out what cylinder to go for a project.

[wobbly]

I have not even seen inside a 3MA so have absolutely no idea about power potential.
Post a bunch of pics on here.
Baseline for the 3XV is the small duct exit , PV closes all the 3 Exhausts , the narrow 14mm boost , tiny Aux that can be made huge and triangular , plus of course only 5 port and bolts straight on.
SP is NFG

[41juergen]

The 3MA10 cylinders from the MJ 1990 3MA3 also have low timings (192/126), but a wider C-port and a more rectangular A-port what makes it difficult to get the triangle shape of the aux export and so the required blowdown..

354635

[wobbly]

A wider C port is not optimal ,and means the B rear wall cant be moved around as much.
The big issue though is the dumb rectangular Aux port - even looks like the useless 4DP.
You would have to weld up 1/2 that port to get the triangular shape needed to prevent vertical short circuiting , and reduce the effect of port linking
to the A via the small end hole.

[diesel pig]

The 3MA cylinder I have looks like just like the one 41juergen posted. I think you have helped make up my mind, The 3XV seems to be the one to use.

[lohring]

Re spark plug projection: Removing the plug washer is a trick used in karting to get the spark closer to the center of the combustion chamber. I have no data on how much if any this helps.

Lohring Miller

[wobbly]

Plug projection - yes and no. I spent hours setting up the long version R7282A -105 used in Honda's with under plug deto sensor to remove the extra 3mm of thread
to have the electrodes well into the combustion chamber middle. Made no difference at all in a KZ.
But Frits has done a similar thing by removing the bare unthreaded end of a conventional plug , and reports that its as good as the all conquering R7376 for way less dollars.

[Orengo98]

A Bultaco head, isn't it? All Bultacos I've worked on had long reach spark plugs so I wonder what type yours is.
Anyway, never fit a short reach plug in a long reach head or vice versa. And if your head was modified from a short to a long reach plug, chances are that it was not the only modification, so you may forget about the manual in this respect.

Hi Frits!

Thanks for the reply. Yes, It's an early Bultaco head yes! It has that typical "trench" combustion chamber.

You're right, all Bultacos have long reach Spark plug, except the 100cc and 74cc models.
The bike I'm rebuilding is a Lobito AK 100, a factory racer based on the Lobito trail bike, to compete against Hodakas in the 100cc class in the US.
It seems to be stock, I can't see any modification to it. I've asked a friend that has the same model and he sent a picture, and the same happens:

354636

So it must be this way from the factory, but I don't know why. I've tried using a long reach spark plug and protrudes around 1mm:

354637

What would you do? With this being a 100cc engine with a 14:1 head, using one plug or the other is going to affect the compression ratio considerably also.

Thanks in advance!


Re spark plug projection: Removing the plug washer is a trick used in karting to get the spark closer to the center of the combustion chamber. I have no data on how much if any this helps.

Lohring Miller

Hi Lohring!

Thanks for your comment. Funny considering this cylinder and head where designed initially for the 100cc direct drive kart class.
The picture above is using the plug washer and a long reach plug. It protrudes about a mm.

[wobbly]

I have searched again many times , but cant find the original NGK technical bulletin that said the new range of plugs with the end threads removed , were actually intended to protrude exactly that 1mm.
Any body protrusion into the chamber is specifically banned in many kart classes , but the electrodes are not " the body " , just a piss off it didnt work in the KZ.

[Flettner]

The water cooled, twin exhaust port, twin blade powervalve cylinder slowly happening. A first I believe?
I might retain the cylinder from underneath so as to get more exhaust port wall access to water cooling.

[ken seeber]

Anyone rolling exhaust cones?

You need one of these:

https://www.facebook.com/share/r/trQXjRaXzoEkZZgm/?mibextid=oFDknk

[diesel pig]

Anyone rolling exhaust cones?

You need one of these:

https://www.facebook.com/share/r/trQXjRaXzoEkZZgm/?mibextid=oFDknk

I must spent two minutes watching that( the video is only 5 seconds long)

considering how long I have spend fighting manual rollers I am green with envy.

[JdG]

https://youtu.be/KX6FnYgXdHM?feature=shared

Just because it can be done [emoji4]

I’m stunned that this even runs, especially when using such rudimentary tools.


Verzonden vanaf mijn iPhone met Tapatalk

[Storbeck]

This guy must have watched an Allen Millyard video then turned to his buddy and said "hold my beer"







https://youtu.be/KX6FnYgXdHM?feature=shared

Just because it can be done [emoji4]

I’m stunned that this even runs, especially when using such rudimentary tools.


Verzonden vanaf mijn iPhone met Tapatalk

[136kg136ps]

BRC making progress on it's 600 twin. Posted an update and pix on Facecrack. He was clear that Frits, Jan and Wob were a lot of inspiration and it shows in transfers, exhaust and cooling regimes. If only there were more 100, 125 and 175 cc "street" cylinders similar.

https://www.facebook.com/brcracingcanada/posts/pfbid0jWstYS1ZvpLxFJAavWGAGXqVaiVBWfPBtv6zRGCNWiM6 yzs8qsNE3DFtzpDF31exl?comment_id=794000995990810&notif_id=1714764453122684&notif_t=feedback_reaction_generic&ref=notif

[Peter1962]

BRC making progress on it's 600 twin. Posted an update and pix on Facecrack. He was clear that Frits, Jan and Wob were a lot of inspiration and it shows in transfers, exhaust and cooling regimes. If only there were more 100, 125 and 175 cc "street" cylinders similar.

https://www.facebook.com/brcracingcanada/posts/pfbid0jWstYS1ZvpLxFJAavWGAGXqVaiVBWfPBtv6zRGCNWiM6 yzs8qsNE3DFtzpDF31exl?comment_id=794000995990810&notif_id=1714764453122684&notif_t=feedback_reaction_generic&ref=notif

Cooperation between some of the best technicians, and the most knowledgeable two stroke geniusses from canada, the netherlands, and new-zealand. :wings:

I hope this cylinder can be bolted on the KTM 300SX cases.

[jbiplane]

My tear create Electronic unit for starter generator.
It is possible use offshelf brushless motor to start engine.

https://www.youtube.com/watch?v=mKLKXB7CXE0

[CrizR]

Plug projection - yes and no. I spent hours setting up the long version R7282A -105 used in Honda's with under plug deto sensor to remove the extra 3mm of thread
to have the electrodes well into the combustion chamber middle. Made no difference at all in a KZ.
But Frits has done a similar thing by removing the bare unthreaded end of a conventional plug , and reports that its as good as the all conquering R7376 for way less dollars.

Great info Wob, thank you!!


Anyone rolling exhaust cones?

You need one of these:

https://www.facebook.com/share/r/trQXjRaXzoEkZZgm/?mibextid=oFDknk

Man that would make it all much much easier!

Hey guys I was searching around for the big end oiling options and couldn't find anything about it here, if someone can point me to the right page would be greatly appreciated.

The most I've found online is this....354679354680

[F5 Dave]

Yes, a good option is to mix oil in with the petrol or introduce it into the inlet. In the late 60s (my T125 Stinger is an example) they formed a complex array of drilling etc. That was all abandoned.

So my primary question is: Why?

At the bottom feeding level, I used to buy old motors to race with as it seemed cheaper and i was skint. The micro rust killed the bearings as soon as you asked them questions (and revs) they didn't want to answer.

New parts were the answer.

. . . Until further questions (and revs) were asked. Careful parts selection and often resizing were another answer.

[Pagi]

Woobly,

I saw that you use this box, https://www.ebay.com/itm/116174503000?_trkparms=amclksrc%3DITM%26aid%3D1110 006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D26418 4%26meid%3D5c1ba07b79644ab781071f2124381e9

do you use it on the dyno with EGT and CHT? if so, when you have found the best jet for the RAD / day, do you have a red light or two that comes on...? how do you adjust the sensitivity ...?

[wobbly]

I dont use CHT as it tells you nothing useful about the combustion parameters.
The deto gauge I setup such that a couple of the indicator lights come on during a normal test - this is the inherent background noise of the running engine.
As I lean the engine down , one or two more may flicker on.

But it happens all the time, as I approach the point where the egt is about to flat line on the next leaner jet , the red , deto , light will flicker.
If I was dumb enough to go one leaner the egt would drop at the same time as I get a hard red - showing 5V on the logger.
The flickering red deto light is a much more definitive metric , as a flat line egt is very hard to actually recognize on the screen in real time.

Here is the 8mm Bosch sensor fitted to the head of a KZ on the dyno.

[Pagi]

I dont use CHT as it tells you nothing useful about the combustion parameters.
The deto gauge I setup such that a couple of the indicator lights come on during a normal test - this is the inherent background noise of the running engine.
As I lean the engine down , one or two more may flicker on.

But it happens all the time, as I approach the point where the egt is about to flat line on the next leaner jet , the red , deto , light will flicker.
If I was dumb enough to go one leaner the egt would drop at the same time as I get a hard red - showing 5V on the logger.
The flickering red deto light is a much more definitive metric , as a flat line egt is very hard to actually recognize on the screen in real time.

Here is the 8mm Bosch sensor fitted to the head of a KZ on the dyno.

thank you very much sir:niceone:

[Flettner]

Great info Wob, thank you!!



Man that would make it all much much easier!

Hey guys I was searching around for the big end oiling options and couldn't find anything about it here, if someone can point me to the right page would be greatly appreciated.

The most I've found online is this....354679354680

Too slow to introduce oil in relation to load.

[skako]

Great info Wob, thank you!!



Man that would make it all much much easier!

Hey guys I was searching around for the big end oiling options and couldn't find anything about it here, if someone can point me to the right page would be greatly appreciated.

The most I've found online is this....354679354680

Hi,
I would solve the effective lubrication of the crank pin bearing in this way.
354684

[wobbly]

As part of the project of fitting TZR250 - 3XV roadbike cylinders to a 4DP TZ250 racebike I am spending a fortune to actually finalize the debate about
what piston and chamber configuration makes the best power.
Jan had already tested the domed piston with a bathtub Vs a part spherical so that wasn't needed , so I will do
a bathtub Vs a toroid on the 98 YZ125 Wossner domed piston.
I have already tested the part spherical against the toroid on a flat top , so this time its the almost flat top VHM TZ 250 piston with a bathtub Vs a toroidal.

The pipe has been updated a little and we now have 54Hp Crank per cylinder on petrol with no deto , and the torque dip has been flattened out , so this should satisfy many peoples curiosity.
This curve is with RS125 VF4 and 40mm Lectron HV carbs that may not yet make it onto the bike for dyno testing.
The spark plug is a 10mm version of the R7376 , as this will reduce the shadow or masking effect created by the toroids intrusion into the loop flow regime , but will have no effect I believe in the bathtub.

[Condyn]

This development is exciting to see Wobbly. Thank you for sharing. Are you still using the oddball reverse two piece baffle? ( steep to shallow ) Also I am curious what area of the pipe you focused on to flatten out the tq dip if you do not mind sharing. Thanks again.

[wobbly]

Yes the concave weirdo rear cone still makes the best power spread - Yamaha's idiot short stroke makes it so hard to get it to overev , and that configuration just seems to work best.
I have a tried a short/shallow and then steep long second rear cone like the Jolly/JL and of course the 3 cone Aprilia style , and all manner of single cones , but no , it wants weird - end of.

I gained some front side by going away from the longer than normal and steepest last diffuser ( No 3 ) and ended up with a steep long mid ( No2 ) diffuser , with a very short/shallow last ( No3 ) diffuser, like the Aprilia,
that at least gave a flat torque with no dip , however small.
Strange , as the longer/steeper No3 works so well ( much shorter TL though ) for front side power in the TM - R1,R2 pipes - but no PV of course.

But this large series of iterations has highlighted for me the real issue with the Aprilia 102 type design , the No1 diffuser is miles too long.
And also shows how dead cool the very old spool PV design is where it closes off all 3 ports - but with differing timings , something Neels put into the code that was super useful.

[Frits Overmars]

Wob, I am impressed by your generosity. Most of us may not realize how much research you are giving away here.

[wobbly]

Yea well Frits I am trying to optimize a 1991 TZ250 using as much trickery as i can muster.
As I have explained elsewhere this whole 10 year series of Yamaha's were pig slow due to their fixation on the short stroke and adding as many transfer ducts as they could.

Some of the results will help others, but hey all this thing can win is a National Trophy for a set period racebike, big deal , so I feel no need to be a secret squirrel.
The 3XV roadbike has "normal" 5 transfers that can be Apriliaized , and the Ex duct exit hits 0.8Mach at the 50 Hp level with no welding needed.

We have moved far along from the old so called A Kit and Jolly/JL pipe designs , all enabled by Neels code , so all I am doing is using experience and technology to improve the mousetrap
so more people can catch more mice.
Not quite as cool as a Kart World Title , but I have a bunch of those already.

Edit : As I said to Jan a short time ago , his contributions as espoused by your online explanations I use nearly every day - Im just expanding on that with newer , and now tested ideas.

[Condyn]

Agreed Frits, very generous indeed.

[F5 Dave]

And makes great reading.

[diesel pig]

I would like to add my thanks as well, it mean's us lesser mortals don't waste time chasing mice that are not worth catching.

[Vannik]

We have moved far along from the old so called A Kit and Jolly/JL pipe designs , all enabled by Neels code , so all I am doing is using experience and technology to improve the mousetrap so more people can catch more mice.

Edit : As I said to Jan a short time ago , his contributions as espoused by your online explanations I use nearly every day - Im just expanding on that with newer , and now tested ideas.

A big part of where EngMod2T is today is from you sharing your test results so generously. I do thank you!

[Frank S.]

Apriliaizing 😀, thats what we do to our twostrokes.
Thanks to the experts sharing their huge knowlege
👍🏻👍🏻👍🏻

[pete376403]

Turned up on facebook - seems appropriate to put it here

[husaberg]

We have moved far along from the old so called A Kit and Jolly/JL pipe designs , all enabled by Neels code , so all I am doing is using experience and technology to improve the mousetrap
.
It just occurred to me that Roberts JR bike was converted to Yamaha pipes dimensions and I think porting in 2000, I wonder if that was by proxy also Honda A Kit. like the KTM also seem to have been, It might explain why that Cagiva came alive in 1995 and why Cagiva and Yamaha keep changing bore and stroke and exhaust porting.

[wobbly]

The Roberts stuff was all Bud Askland , in mid 1999 I was at his workshop and he already had the new square 5KE cylinder and Kit pipe dimensions on the drawing board.
He had a Czech CNC anemometric flow machine running , as did Yamaha in 1999 according to Suzan the head engineer I met at Philip Island where Jaques finalized the 250 title.
Suzan ( ringlish name ) said that with the flow machine he did not need a dyno anymore , and he had brought a set of 500 cylinders with him, that would give a bunch of top end power to suit the track.
No idea though what was done to the Cagiva at the time , a bit before I started getting into the pits.

[41juergen]

Yea well Frits I am trying to optimize a 1991 TZ250 using as much trickery as i can muster.
As I have explained elsewhere this whole 10 year series of Yamaha's were pig slow due to their fixation on the short stroke and adding as many transfer ducts as they could.

Some of the results will help others, but hey all this thing can win is a National Trophy for a set period racebike, big deal , so I feel no need to be a secret squirrel.
The 3XV roadbike has "normal" 5 transfers that can be Apriliaized , and the Ex duct exit hits 0.8Mach at the 50 Hp level with no welding needed.

We have moved far along from the old so called A Kit and Jolly/JL pipe designs , all enabled by Neels code , so all I am doing is using experience and technology to improve the mousetrap
so more people can catch more mice.
Not quite as cool as a Kart World Title , but I have a bunch of those already.

Edit : As I said to Jan a short time ago , his contributions as espoused by your online explanations I use nearly every day - Im just expanding on that with newer , and now tested ideas.

And the idea was born based on your advise: to get power, you have to balance the STA's... thank's a lot for sharing all the wisdom with us!

[husaberg]

The Roberts stuff was all Bud Askland , in mid 1999 I was at his workshop and he already had the new square 5KE cylinder and Kit pipe dimensions on the drawing board.
He had a Czech CNC anemometric flow machine running , as did Yamaha in 1999 according to Suzan the head engineer I met at Philip Island where Jaques finalized the 250 title.
Suzan ( ringlish name ) said that with the flow machine he did not need a dyno anymore , and he had brought a set of 500 cylinders with him, that would give a bunch of top end power to suit the track.
No idea though what was done to the Cagiva at the time , a bit before I started getting into the pits.

Around 94 Cagiva changed its bore and stroke to 54x54 and in my Cagiva album are these pics these would be looking at them much earlier.
George V.....(the short fella)whose last name escapes me came from HRC to Cagiva about the time they started to get competitive.
my understanding was yamaha helped Cagiva but maybe the tech went both ways....they even went to Keihin carbs at the same time.
354697354698354699




Then we have this change in 1997 for Yamaha to bridged exhaust from the superior triple port the year before was the move to 54x54mm.
https://global.yamaha-motor.com/showroom/cp/collection/racing_yzr500_0wh0/
354700

On this model, the "V" bank of the 4-cylinder engine was widened from 70 to 75 degrees in order to allow an increased air box capacity. A "T" type exhaust port (existing 3-port layout changed to 2-port) known for its excellent pick-up characteristics was also adopted experimentally on this model. This combined with a new crank assembly spec and a higher drive shaft position to achieve improved handling stability. On this machine Cadalora mounted the winners podium twice with 2nd-place finishes and twice with 3rd place to finished the season ranked 6th
in 98 they went to Honda owned Keihin carbs a well.
it's just supposition of course.

[41juergen]

I got 5 L of this Motul Outboard 2 stroke oil. Is that ok for use in a road going sports bike?

354706354707

[yatasaki]

I got 5 L of this Motul Outboard 2 stroke oil. Is that ok for use in a road going sports bike?

354706354707
No, TCW3 oils are made for cool and slow spinning engines.
Believe me, didn't work well on mopeds, chainsaws, and scooters

[wobbly]

CNC inserts done for the big piston/head shape shootout - 4 pairs.
Head covers awaiting some material.
Just have to spend a couple of days grinding ports - my favorite job , Not - then have the plating done.

[Grumph]

i remember seeing a post showing the layout of a thermosyphon system with thermostat.
By wobbly I think.
The search function isn't finding it for me.
Anyone keep a copy or know where it is ?

thanks

[husaberg]

i remember seeing a post showing the layout of a thermosyphon system with thermostat.
By wobbly I think.
The search function isn't finding it for me.
Anyone keep a copy or know where it is ?

thanks

it wasn't wobbly...
he did post a few with thermostats.

https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1131218438#post1131218438

[Grumph]

Thanks Husa for that. Memory said it was thermosyphon.
Now looking at pump drives.

[husaberg]

Thanks Husa for that. Memory said it was thermosyphon.
Now looking at pump drives.

for your application look at how a KTM50 drives it

https://www.youtube.com/watch?app=desktop&v=8rw9XgfQrF4
They just drive it off a tab nut on the mag shaft. they have also the sexiest tiny mag you will see. they later ones are digital.
or off the third shaft and accept they have to leave it in gear on the grid

[F5 Dave]

Wonder how long a tool battery would drive an electric pump? If of course you don't have an alternator. A Turbo booster brushless pump worked well on the MB100.
But I did have the CR250 stator and ignitech. Never sagged voltage on the dyno.

[wobbly]

So here is the next interesting project , YPVS 350 classic racebike on pump gas - no deto.
This thing also has the old Yamaha drum PV , but no Aux ports - so way better than the original Banshee.
Its got a Nova close ratio set in it , so it was begging for me to go spastic on the tune.
It went thru the roof in the sim when I added the Wobbly duct and that damn weird concave rear cone - again.
I Apriliaized the porting again like the 3XV, but wont know what head to put on it until those are dynoed in the TZ250 test session.
Only domed TZ350 single ring race pistons are available from Meteor, so it will be ported , then the stock size iron bore plated to be able to keep on using that same piston size.

[41juergen]

Hey Wob, would that be an option for your project? Not yet solved is the design of the PV drum channel for the aux ex port..

354711

[wobbly]

The 31K would need a PV drum exactly like the 3XV , maybe a step too far for the customer.
But he is over the moon about the results so far anyway.

[41juergen]

The 31K would need a PV drum exactly like the 3XV , maybe a step too far for the customer.
But he is over the moon about the results so far anyway.

Got it, the 3XV may not really suit as the stock 31K drums are not as wide in that area and have the bushes in the way... :niceone:

[wobbly]

I see the red marker for widening the B port , what piston are you thinking of for this , the Meteor TZ350 was the only single ring pinned over the boost I know of.

[husaberg]

the Meteor TZ350 was the only single ring pinned over the boost I know of.

Challenge Accepted...

[41juergen]

I see the red marker for widening the B port , what piston are you thinking of for this , the Meteor TZ350 was the only single ring pinned over the boost I know of.

At that time it was still possible to get small customized lots (2 pieces) from Woessner (with a 66.0 mm diameter)... This drawing had the ring peg at 30° left or right of the C port, the final version had the one ring peg running over the C port.

354712

[husaberg]

Not sure where it is pinned

https://www.tkrj.co.jp/goods/m-AY0980X-31K.php

https://www.tkrj.co.jp/img/goods/img_piston.jpg

<tbody>
ODEL
RZ-350RR for RACE


OEM No.
31K


CODE No.
AY0980X


BORE(mm) ：Ａ
64


LENGTH(mm) ：Ｂ
72


PIN DIA (mm) ：C
16


COMPRESSION HIGHT① (mm)：D
40


COMPRESSION HIGHT② (mm)：E
36


PIN LENGTH (mm) ：Ｆ
54


PLATING
O


STROKE
2


PISTON　CODE No.
PY1280X

</tbody>


nz post classic allow up to 410cc or so dp Aussie rules allow over 350cc ?

[wobbly]

Thanks Husa, I have emailed them about the pin position.
I can get the Meteor wholesale , but these are even better , and can go up in size before the bore is plated.

[wobbly]

Idiots put the single ring pin in the stock position , between the B and boost port.
So sadly not a " race " piston at all.
Juergen - I had some Wossner specials made last year , 66mm for a 400 racebike , they now demand 10 off.

[SwePatrick]

Relocate the pin then.

[husaberg]

Idiots put the single ring pin in the stock position , between the B and boost port.
So sadly not a " race " piston at all.
Juergen - I had some Wossner specials made last year , 66mm for a 400 racebike , they now demand 10 off.

Buggar, Tell them what you want and the market there is for alternatives and I think you might find them quite accommodating.
I see they do RS125R Honda ones now. After all What is there to lose.
Personally I would not open with "you idiots"...:innocent:
I had a look through a lot of pistons I was surprised how many MX were pinned like that
I even seen a two ring piston that had the pins in the same location with no overlap at all?

KTM200 pistons are the long enough? or available in single ring?
single ring yes not sure where pinned I have never seen one
but they do have good long rods for a Yamha twin.
https://pic.ebid.net/upload_medbig/6/6/5/1355563997-5523-9.jpg

[NickL89]

So here is the next interesting project , YPVS 350 classic racebike on pump gas - no deto.
This thing also has the old Yamaha drum PV , but no Aux ports - so way better than the original Banshee.
Its got a Nova close ratio set in it , so it was begging for me to go spastic on the tune.
It went thru the roof in the sim when I added the Wobbly duct and that damn weird concave rear cone - again.
I Apriliaized the porting again like the 3XV, but wont know what head to put on it until those are dynoed in the TZ250 test session.
Only domed TZ350 single ring race pistons are available from Meteor, so it will be ported , then the stock size iron bore plated to be able to keep on using that same piston size.

Hi Wobbly,

Could you share the pipe dimensions by any chance?

[wobbly]

Yea OK Husa I will very politely ask if they will do some with a 6 o'clock pin , but they havnt even bothered to reply to my pin position request after a week.

That whole ring pin scenario is a personal sore point , as when I pointed out to a reply on a forum , where some " idiot " replied that no way can you put a pin over the boost port , as the ends would immediately " catch "
I got blocked for saying he was a moron as its been done since the middle of last century by every manufacturer ( except TKRJ ) with no issues at all.

Re the pipe dimensions for the YPVS - not my intellectual property , so I have asked for the customers permission to publish.

[pete376403]

[QUOTE=wobbly;1131225537]Yea OK Husa I will very politely ask if they will do some with a 6 o'clock pin , but they havnt even bothered to reply to my pin position request after a week.[QUOTE]

Or ask if they can do pistons with NO pin and you will install it where you require

[F5 Dave]

Thing about a racebike is that you don't want to build it only once so replacement are ideally, have a set on the shelf and know that they can be replaced.

100cc bucket was a drama. YZ100 piston circa 1978 were kinda ok. . . Ish.
But only available NOS from random Ebay suppliers in 1 qty.

I grew sick of the increasing risk and went to Kart piston. Of course that means destroking the crank and a oversquare engine.
Convenience trumped design. It had to.

[husaberg]

Yea OK Husa I will very politely ask if they will do some with a 6 o'clock pin , but they havnt even bothered to reply to my pin position request after a week.

That whole ring pin scenario is a personal sore point , as when I pointed out to a reply on a forum , where some " idiot " replied that no way can you put a pin over the boost port , as the ends would immediately " catch "
I got blocked for saying he was a moron as its been done since the middle of last century by every manufacturer ( except TKRJ ) with no issues at all.

Re the pipe dimensions for the YPVS - not my intellectual property , so I have asked for the customers permission to publish.

Try prox they have an order frrm they do center pinned KTM200 in suitable sizes but not sure in the center pined are single ring.
We have a Japanese interpreter available on ESE as well.
https://www.pro-x.com/wp-content/uploads/2023/01/TECHNICAL-2023.pdf

[wobbly]

Husa ,I researched the KTM from PROX the 01.6249 and it says the ring pins are 1.75mm off the center , so two ring , but almost over each other.
Unless I simply leave the second ring out.
Looks like the Meteor TZ350 is the go atm , unless TKRJ decide to reply at all.

Re the YPVS pipe design , the customer is not keen on me publishing it at all , so end of.
But here is the TZ250 - 3XV latest iteration , thats being fitted to the bike as we speak.
The designs are very similar , with the Wobbly duct generating 0.8 Mach and the concave rear cone setup at about the same diameter , but this has peak Hp at 12750 , the RZ350 is at 10750.
The TL is 965mm but I didnt tell you that.

[husaberg]

Husa ,I researched the KTM from PROX the 01.6249 and it says the ring pins are 1.75mm off the center , so two ring , but almost over each other.
Unless I simply leave the second ring out.
Looks like the Meteor TZ350 is the go atm , unless TKRJ decide to reply at all.

Re the YPVS pipe design , the customer is not keen on me publishing it at all , so end of.
But here is the TZ250 - 3XV latest iteration , thats being fitted to the bike as we speak.
The designs are very similar , with the Wobbly duct generating 0.8 Mach and the concave rear cone setup at about the same diameter , but this has peak Hp at 12750 , the RZ350 is at 10750.
The TL is 965mm but I didnt tell you that.

Sorry I was looking at some others that were single ring for KTM200 then looking at the 66mm 250 ones and got a bit confused as some of those are prox single rings.
here is a single ring pined in the rear at least in the pic
https://www.amazon.com/Namura-Top-End-Repair-NX-70022-BK/dp/B00T6JKANS

https://m.media-amazon.com/images/I/61eHQVsgUgL._AC_SL1000_.jpg

[Tim Ey]

Regarding 64mm Pistons:
I got some made at Wössner for a special Vespa cylinder.

354720

The current batch is sold out, but I will probably order another batch this year.
BR Tim

[crbbt]

I am looking for some guidance for what to use for a stand alone det detector.

Googling det detector brings up a bunch of HRC models which don't seem to be available any more.

but searching for knock detector instead brings many 4 stroke solutions.

are the Link products good?

thanks

[wobbly]

I have used this on my dyno for over 10 years and sold dozens to customers - works perfectly

https://www.ebay.com/itm/116174503000?_trkparms=amclksrc%3DITM%26aid%3D1110 006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D26418 4%26meid%3D5c1ba07b79644ab781071f2124381e9

[SwePatrick]

Started a new little project, so i´m presenting it here with a little shoutout as i am searching a head for this engine. (SGM Maranello GA207)
Anyone got one lying around to no use?


So how can i destroy this the fastest easiest way without using violence? =)


https://www.youtube.com/watch?v=8IQI4HakVnY

[crbbt]

Thanks Wob!

[Frits Overmars]

..........354722

[Wos]

Dear Jan, Dear Mentor :2thumbsup:

Happy Birthday to You !!:clap: ;)

[Niels Abildgaard]

Some help needed for this gentleman I think.
If it has been linked before here I have missed it

https://research.chalmers.se/publication/534994/file/534994_Fulltext.pdf

[Vannik]

Some help needed for this gentleman I think.
If it has been linked before here I have missed it

https://research.chalmers.se/publication/534994/file/534994_Fulltext.pdf

As of Saturday he is now Dr Lennarth Zander. He also published a book on engine simulations a few years ago, do a search on "Boostbusters".

[wobbly]

So we now have a proven 50Kw turbocharged 125cc 2T engine = 67 Hp.

Im so happy he did not destroy the whole project by claiming it would rev to 30,000 rpm - if you are reading this Luc , note well.

Also the complete dismissal of a supercharged system , with verifiable logic as to its unsuitability , is something I tried to convince Two Stroke Stuffing of 3 years ago.

[Niels Abildgaard]

So we now have a proven 50Kw turbocharged 125cc 2T engine = 67 Hp.

Im so happy he did not destroy the whole project by claiming it would rev to 30,000 rpm - if you are reading this Luc , note well.

Also the complete dismissal of a supercharged system , with verifiable logic as to its unsuitability , is something I tried to convince Two Stroke Stuffing of 3 years ago.

I am not sure it was claimed that the 125 thing would do 500 rps,
but that ignition system could?.

[husaberg]

I am not sure it was claimed that the 125 thing would do 500 rps,
but that ignition system could?.
The 30K straight came from the horse ass I mean mouth...




We still can made the engine with 70hp and a max speed of 30k
But that is not the engine we want to sell, so after a long search we managed to get the result we published.

Regards,
Luc

[LUCFLucF
0
Joined: 29 May 2015, 11:35
Re: 2 stroke thread (with occasional F1 relevance!)
0
Post 07 Aug 2015, 00:35


Ryger Engine built by Mcd Twist Ryger Engine
125 cc, over 80% less emissions, 70 bhp, max. rpm 30.000.


Ryger Engine production running in high gear in order to meet cik regulations.


I can't find the button to attache pictures!! So .... https://www.facebook.com/mcd.twist.9?pnref=story

https://www.f1technical.net/forum/viewtopic.php?t=10966&start=645



The Ryger effect is a process in which large amounts of money are transformed into over-hyped smoke and mirrors, gag orders and condescending insults to anyone who questions the validly in anyway of a secret design that alledgdly makes 1.5 times the power of the most powerfull engine 70Hp for a 125 and revs to 30,000rpm

He also claimed to have had somewhat fictitious conversations with me via PM where it seems I claimed I would not share the patent holders name.

[Niels Abildgaard]

The 30K straight came from the horse ass I mean mouth...





I had not seen that for hatesmokescreen

[Frits Overmars]

https://research.chalmers.se/publication/534994/file/534994_Fulltext.pdfA very pleasant read :niceone:. Thank you Dr Lennarth Zander.

[lohring]

Compounding two strokes has been studied for a long time and is still used today. My favorite examples are the Rolls Royce Crecy (https://en.wikipedia.org/wiki/Rolls-Royce_Crecy) and the Napier Nomad (https://en.wikipedia.org/wiki/Napier_Nomad). Modern examples are container ship diesel two strokes and snow mobile engines. The best modern change is the development of the electric motor/generator coupled with the turbocharger. This allows startup and low rpm scavenging without a mechanical blower. If you add a battery pack you can store excess power from the turbine as well as regenerative braking from a hybrid drive system. This is the Formula 1 system (https://www.carmagazine.co.uk/hybrid/how-f1-engine-works/). I believe Garrett is exploring this application (https://www.garrettmotion.com/emission-reduction/garrett-e-turbo/) though with four stroke engines. It would be a perfect combination with the Achetes (https://achatespower.com/) opposed two stroke.

I happen to have a motor generator. I'm not sure exactly what it is and it would need an electronic controller to work. If anyone has a use for it I would glad to give it to you for the shipping cost.

354736

Lohring Miller

[wobbly]

Frits , you are always strangely silent when anything Ryger is mentioned , yes I know a NDA was in place , but I believe you actually drove a kart with the engine on board.
My tin foil hat is crinkling as I write this.