ESE's works engine tuner

[Condyn]

Does anyone have a developed engmod pack file for a modern-ish Yamaha yz250 that I could get my hands on?

[Muhr]

Sorry I didnt word my fist description correctly.

Ok understand! 👍

[wobbly]

Condyn , I have a stock YZ250 pack from years ago - PM me with your email.

[DoldGuy]

Condyn , I have a stock YZ250 pack from years ago - PM me with your email.

Wobbly,

I’d appreciate a copy also...PM sent.

Thanks in advance.

[Flettner]

These two cylinders freshly cast, destained for the 700cc track bike.

[ceci]

These two cylinders freshly cast, destained for the 700cc track bike.

I feel disappointed, I thought that in this new engine I would try some new solutions that can increase power.
It is very frustrating for those who do not have the means and cannot do anything, to see how those who can do it do not do it.
There are already many 700cc two-cylinder motorcycles "with KTM cylinder and others", there are even those with CR500 cylinder, but none of them have anything new. And less when it comes to power increase.
I hope you understand me and don't be offended

[Javier Ruda]

if the transfer ports and the blowdown are not granted, there is no point in enlarging the admission.

for admission, I am inspired by the kart rotax max cylinder.

I have tried to copy Rotax Max admission:


--- Crankcase before ---
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=351151&thumb=1&d=1653503748


--- Crankcase after ---
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=351150&thumb=1&d=1653503763


--- Cylinder underside ---
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=351149&thumb=1&d=1653503795


--- Boyesen ports before (right) and after (left) ---
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=351148&thumb=1&d=1653503815


I copied this because I like Rotax Max power curve, with peak at 12000 rpm, and I guess that this intake type can be beneficial, but I am not sure at all.

Does anybody knows the phisycs behind this evolution on the Rotax engines?

[Flettner]

I feel disappointed, I thought that in this new engine I would try some new solutions that can increase power.
It is very frustrating for those who do not have the means and cannot do anything, to see how those who can do it do not do it.
There are already many 700cc two-cylinder motorcycles "with KTM cylinder and others", there are even those with CR500 cylinder, but none of them have anything new. And less when it comes to power increase.
I hope you understand me and don't be offended

You will note the cylinders have the quad injector lugs.
Its not the only engine Im building.

[TZ350]

.
More from 2Stroke Stuffing:- https://youtu.be/7Dk9nYfO7Wc a change of direction.

Rotary exhaust valve was great for a wide spread of power but now looking for peak power using supercharger and expansion chambers.

[ceci]

You will note the cylinders have the quad injector lugs.
Its not the only engine Im building.

Flettner, you know what I mean, to supercharge the cylinders, in the way that I indicate wobbly, of which I made a suggestion to be with separate pipes and with operation control.
I do not think it is incompatible with the use of the TPI mk2 system, on the contrary I think it would improve reducing the loss of HC

[wobbly]

My opinion would be that its near on impossible for someone like Flettner to spend his working life learning to be an expert in CNC machining , metal casting / pattern making to enable him to
run a business making money building aero gearboxes and gyro aircraft - and on top of this effort to become an expert in the latest two stroke technology such as using EngMod and designing pipes etc.
I can manipulate 2T data and do the CAD work to build anything using 3D laser technology , he cant , simply as there isnt sufficient time in each day , but then I have no clue when it comes to foundry skills .

He does the two stroke thing as much as a hobby interest as it is a commercial enterprise , and I would love to be able to learn his skills - but then its taken me a lifetime of learning how to
make a living out of the small part Neil cant do.

[Flettner]

My twostroke endeavors are just a hobby, like most everyone else here. Although it can get quite engaging sometimes.

[TZ350]

351160

Tupper Ware lunch box. All in one, carb cover and catch tank.

Second try at protecting the carb from wind blowing across the bell mouth and upsetting the mixture.

[pete376403]

351160

Tupper Ware lunch box. All in one, carb cover and catch tank.

Second try at protecting the carb from wind blowing across the bell mouth and upsetting the mixture.

With the hole pointing forward you will get a ram effect, theoretically raising the air pressure above atmospheric depending on speed. How you going to jet for that? Would it not offer a more consistent air flow with the hole pointing to the back?

[F5 Dave]

I'm still a bit hungry. What was in that before? If it doesn't work, can you still claim a replacement on that famous Tupperware warranty?

Or for shame - have you cheaped out on an inferior copy?

[wobbly]

Ram effect , has no useful effect at all till well over 100Km/Hr.
And GP/Moto bikes had/have long , small area intake tubes connected to large volume air boxes that form proper Helmholtz tuned systems.
Robs plastic thingy may help prevent carb standoff being affected , and keep rocks out , thats about all he wanted I believe.

[ceci]

Flettner, you know what I mean, to supercharge the cylinders, in the way that I indicate wobbly, of which I made a suggestion to be with separate pipes and with operation control.
I do not think it is incompatible with the use of the TPI mk2 system, on the contrary I think it would improve reducing the loss of HC

This way of supercharging I mean


And adding to the effect of having very high exhaust duration you can cut the skirts short such that the port is open a few mm when the piston is at TDC.
Wreaks havoc with the jetting , but in the project i tried that we were using big pumper carbs.
Very easy to adjust the fuel curve as was needed - but I doubt a normal carb could be made to work.
This setup on a " stock " 950 SeaDoo gave an added 8 Hp in about 80 , so 10% - enough for the title at Havasu.
On a 1180 twin race motor the bump was 15 Hp in 120 so a little less.


That fact intrigues me, filling (supercharging) supplement volume charge for the exhaust why it happens.
How to get that little supplement volume of cargo to the exhaust:
The depression of the main exhaust creates a venturi effect and attracts it
the inertia of the incoming mixture forces it out through this small slot.
Which of the two causes can it be?



I believe it's the split suction wave from the single diffuser that find it's way into the tdc side crank case. Or it's explained on previous pages.


If you mean the video of the 3D figures, if I did it, if what you mean if I have done something like that with a real engine, NO, doing it is not within my reach.
The bottom line is: can cross feed work on engine twins?



As I said i'm not excactly sure why that engine made more power. And also as I said, I think it had a shared pipe with a y- section to the cylinders, so there is no need to have ducts from one cylinder to the other. If your idea works with separate pipes, I don't know.



Not trying to test this solution makes me suspect two things:
Not enough hp increase to create motivation.
Not confident it will work (for separate pipes)

[husaberg]

With the hole pointing forward you will get a ram effect, theoretically raising the air pressure above atmospheric depending on speed. How you going to jet for that? Would it not offer a more consistent air flow with the hole pointing to the back?

on a bucket it will not increase your speed to any great effect but it will f up your jetting to a great effect.
stuff to follow.
351168351169351170351171351172

[Frits Overmars]

With the hole pointing forward you will get a ram effect, theoretically raising the air pressure above atmospheric depending on speed. How you going to jet for that? Would it not offer a more consistent air flow with the hole pointing to the back?Not necessarily; with the backward hole a speed-dependent underpressure could develop behind the airbox which could just as well mess up the jetting, the difference being that the mixture would then become too rich instead of too lean. The piston will like it but you won't win races that way.
I'd rather have a mixture that is too rich at low speeds and perfect at high speeds, when you need full power because of the air resistance.
Fletto, I'll save you the trouble of reacting: with fuel injection we can have the best of both worlds.
351173



Robs plastic thingy may help prevent carb standoff being affected and keep rocks out.Keeping rocks out seems like a good idea, a very good idea.
An airbox will definitely affect standoff. If there is standoff at all, in the absence of an airbox it gets blown away before the engine can inhale it.
An engine with an airbox will re-inhale this standoff that already carries its portion of fuel, messing up the carburation.
This leaves us with two options: omit the airbox or ensure that there is no standoff. I know which option I prefer.

[wobbly]

I think the important take away from that article is the statement that with 135 bhp available , the ram air system at 120mph had 20mB of " boost " and this gave " the odd Hp ".
ie at 120mph is doing F all , and thus wont be affecting the jetting required.
Convert that to bucket power and speed numbers on track , cant see it being an issue.

[Grumph]

Many years back, a local sidecar crew looking for the last bit of HP from their 600 Honda - it was already on large % of nitro - tried ram air.
They did it right with a duct from the high pressure area low in front of the fairing, up and over into the airbox.
After much testing, they were prepared to say that it gave roughly 200 more RPM at the end of the longest local straights. On a good day.

It was left on the bike as much to baffle other competitors as anything else.

[Flettner]

TZ, you need this, throw that shit carburetor away.
https://youtube.com/shorts/rxc1OFcQgPM?feature=share

[crbbt]

almost wouldn't need an inlet valve with that set up

[ceci]

This is the last time I suggest it, I will not talk about this again, nor will I bother you with this issue.
I will never develop it, because I do not have the means to do so, the most is what I have done "CAD 3D"


And adding to the effect of having very high exhaust duration you can cut the skirts short such that the port is open a few mm when the piston is at TDC.
Wreaks havoc with the jetting , but in the project i tried that we were using big pumper carbs.
Very easy to adjust the fuel curve as was needed - but I doubt a normal carb could be made to work.
This setup on a " stock " 950 SeaDoo .

https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=348939&d=1619680525https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=348940&d=1619680548


And also as I said, I think it had a shared pipe with a y- section to the cylinders, so there is no need to have ducts from one cylinder to the other. If your idea works with separate pipes, I don't know.

https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=348942&d=1619680598https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=348941&d=1619680576



This setup on a " stock " 950 SeaDoo gave an added 8 Hp in about 80 , so 10% - enough for the title at Havasu.
On a 1180 twin race motor the bump was 15 Hp in 120 so a little less.

The 10% increase in power is clearly insufficient to "motivate, encourage" to use this system and try to improve it.

[Muhr]

351160

Tupper Ware lunch box. All in one, carb cover and catch tank.

Second try at protecting the carb from wind blowing across the bell mouth and upsetting the mixture.

Nice�� A little dragy but what does it matter.

[wobbly]

Ceci , the problem you are up against is that 180* firing parallel twins with a single pipe are a weird anomaly used in restricted classes of Jetskis and Snowmobiles for packaging/ space/cost reasons only.
Nothing to do with efficiency or power.
The bottom line is that twin pipes make way, way more power and do that with alot less Exhaust port timing needed for the Y and single pipe setup.
They also allow a parallel twin to be run in the " big bang " 90* firing configuration , albeit then needing a balance shaft.

The cut piston skirt idea I developed just as a cheat of the rules to win a world title , it worked , but I can see no other reason to be looking into it as an on going project with some worthwhile end goal.
Those cut pistons also had a ceramic coating ( illegal as well ) equal to 50% of the inner dome area , and once they had been run hard , they colored up in the middle thus camouflaging the coatings existence.
That idea of ceramic coating just the pistons combustion chamber area ( and the chamber itself ) , but not the squishband , does have an application in any 2T race engine , as it reduces the thermal load on the piston - and
the heat rejected into the water cooling system.

Take that idea and you can use it anywhere , as its a guaranteed way of being able to run leaner and make more power.

[TZ350]

TZ, you need this, throw that shit carburetor away.
https://youtube.com/shorts/rxc1OFcQgPM?feature=share

Yes, I love what you have done with the rotary valve sliding gibs for throttle control.

Maybe when I build the next engine. A 69cc turbocharged rotary valve setup. I could copy your sliding gib idea and fuel inject it through the turbo intake.

[Flettner]

Ok, finaly RSW cylinders. You will need to contact Glenn if you are interested.

[wobbly]

Sadly Neil , I cant believe someone got you to copy the oldest and least powerful Aprilia cylinder ever made - before Jan made it work properly.

[Flettner]

Sadly Neil , I cant believe someone got you to copy the oldest and least powerful Aprilia cylinder ever made - before Jan made it work properly.

Sooo... I guess thats a no then

[husaberg]

Sadly Neil , I cant believe someone got you to copy the oldest and least powerful Aprilia cylinder ever made - before Jan made it work properly.

The patterns for anything later were not available for those Wob (at a price i could afford anyway.)

[Flettner]

Sadly Neil , I cant believe someone got you to copy the oldest and least powerful Aprilia cylinder ever made - before Jan made it work properly.

I didnt make these patterns, they have been made by a professional, proper. Above my pay rate.

[husaberg]

I didnt make these patterns, they have been made by a professional, proper. Above my pay rate.

At about 200 hours at my hourly pay rate.....

351186351187351188351189351190351191

[Muciek]

Wobbly could port them before plating? They are from before 1994? https://twitter.com/NeilHodgson100/status/1530823207133102081 Today from Mugello. Sadly he only made one lap.

[Frits Overmars]

The patterns for anything later were not available for those Wob (at a price i could afford anyway.)I don't want to be judgmental about how deep your pockets are Husa, but casting cylinders using those ancient RSW patterns makes me think of taking up smoking because you found a pack of cigarettes.

[ceci]

the cut piston skirt idea i developed just as a cheat of the rules to win a world title , it worked , but i can see no other reason to be looking into it as an on going project with some worthwhile end goal.
.

ok "touché"

https://esgrimasantacruz.files.wordpress.com/2018/06/touche.gif

[136kg136ps]

Are there any current aftermarket cylinders that are more up to date clones of the best RSA iteration? Or should I say incorporating the lessons Jan and Frits have so freely shared.

[husaberg]

I don't want to be judgmental about how deep your pockets are Husa, but casting cylinders using those ancient RSW patterns makes me think of taking up smoking because you found a pack of cigarettes.

Feel free
I feel The patterns can be modified to closely resemble that of the later models internally.
yes they will not have the benefits of the revised colling and head clamping
the "mach 3 septums" that dea improved can also be reconfigured.
But the beauty of this model is that they can be easily adapted to fit a RGV suzuki.
of which Suzuki made quite a few.
although dated they are still better than almost anything available in their current state.
PS i gave up smoking a few years ago, i still miss it occasionally.

[wobbly]

A few years ago I did a CAD project for PVP where they used the last Aprilia cylinder as the baseline for their 250cc Superkart tandem twin.
I signed an NDA so cant give you the files ,but the update made alot better peak and overev power , so getting one of those would give you all the details.
FPE do a similar rendition of the Aprilia for a 250cc tandem as well , but I dont know if they have developed the castings any further.

[Flettner]

Still a bloody sight better than a TF / KE / MB / cylinder, yes.

[wobbly]

Still a bloody sight better than a TF / KE / MB / cylinder, yes..
Yea , but exactly the same amount of effort to build a 55Hp 125 cylinder as it is to build a 45 Hp one.

[TZ350]

Still a bloody sight better than a TF / KE / MB / cylinder, yes.

I would love to have a couple of those cylinders in 100cc (50mm) format. Better yet, some rejected 54mm ones that need re-plating. Will de stroke for 110cc F4 class re bore limit.

Or maybe even better yet. Some machined castings with semi finished bores. That I can finish as required and plate myself.

[Flettner]

.
Yea , but exactly the same amount of effort to build a 55Hp 125 cylinder as it is to build a 45 Hp one.

Well, send me the pattern then, or a solid model of the cylinder you want. Oh, and a big sack of money too.
I repeat, I didn't build these patterns but I will cast some from this pattern, as requested, finally.

If you are going to model a cylinder up, make it a 59/60 bore x 61 stroke please, with full powervalve, on all three exhaust ports. Any bolt pattern, I can live with that.

[wobbly]

Trouble is Neil it would take an even bigger sack of money to do the sim work , then the CAD work on an oddball 59/60 bore/61 stroke cylinder that's never been done before.
Who wants that combination and for what ?

[F5 Dave]

Hmm, 170, 350, 510, 700cc.

Cant provide the sack of cash, but can pay in DaveCoin.

It's a bit like Bitcoin, but with less ability to transfer to any other tradable asset.

[Flettner]

Hmm, 170, 350, 510, 700cc.

Cant provide the sack of cash, but can pay in DaveCoin.

It's a bit like Bitcoin, but with less ability to transfer to any other tradable asset.
In other words, very like bitcoin.

[Flettner]

Trouble is Neil it would take an even bigger sack of money to do the sim work , then the CAD work on an oddball 59/60 bore/61 stroke cylinder that's never been done before.
Who wants that combination and for what ?

Off road 175cc, twin disc valve engine....
350 V twin disc valve, this one can be square.
Or perhaps with a commer. 350 V twin, disc valve engine but also perhaps twin discs per crankcase.

[ken seeber]

Here’s a question of Wob based on a guess that the TM KZ R1 is capable of maybe 51 hp with a rule requirement of 30 mm carb and flat line ignition.

So, if this engine was fitted with a Ø40/42 carb and programmable ign, would it be far off the 55 hp RSA, acknowledging that it was reed (maybe this might need to be enlarged) vs RV?

I’d reckon it wouldn’t be far off, given my lack of knowledge on the sensitivity of friggin 2 strokes. Given this, it’d be a pretty simple matter of taking exh and transfer shapes from the R1, scanning these and then 3D printing coreboxes. Obviously this would be for a 54 * 54 layout only and to suit an engine with the same general power delivery curve requirement of a KZ /125 road race application.

[Frits Overmars]

Here’s a question of Wob based on a guess that the TM KZ R1 is capable of maybe 51 hp with a rule requirement of 30 mm carb and flat line ignition. So, if this engine was fitted with a Ø40/42 carb and programmable ign, would it be far off the 55 hp RSA, acknowledging that it was reed (maybe this might need to be enlarged) vs RV?
I’d reckon it wouldn’t be far off, given my lack of knowledge on the sensitivity of friggin 2 strokes. Given this, it’d be a pretty simple matter of taking exh and transfer shapes from the R1, scanning these and then 3D printing coreboxes. Obviously this would be for a 54 * 54 layout only and to suit an engine with the same general power delivery curve requirement of a KZ /125 road race application.A reed valve engine is less dependent on carburetor diameter than a rotary valve engine. And switching from flat-line ignition to 3D-mapped ignition, ditto power jet and ditto power valve will do more for the power band than for maximum power, so equalling the RSA power figure, 16 years after it was measured, still won`t be a piece of cake.
But in any case, copying Wobs R1 cylinder would be a hell of a lot cleverer than using 1994-Aprilia patterns.

[peewee]

what is this. ktm put one injecter to the rear now it seems

https://i.ibb.co/Rz7FgrG/PHO-BIKE-DET-HQV-23-TC-250-EFI-SALL-AEPI-V1.png

[porttiming124]

Condyn , I have a stock YZ250 pack from years ago - PM me with your email.

Hello Woobly.
Could I have a copy of the yz 250 pack please?
I sent you a PM with my email
thank you

[Flettner]

what is this. ktm put one injecter to the rear now it seems

https://i.ibb.co/Rz7FgrG/PHO-BIKE-DET-HQV-23-TC-250-EFI-SALL-AEPI-V1.png

I think that is the crankcase pressure sensor? Or a sensor of some sort.

[wobbly]

The R1 reed curtain area is capable of 56Hp crank , so is close to the limit now we are making 50.8 Hp sprocket - and the reed port area is equivalent to 41.7mm dia.
But it would in reality probably support 55Hp sprocket as the possible extra air flow and thus column inertia from a big ( 42mm ) carb would simply hold the petals open longer.
The next R2 is in CAD as we speak , so the R1 NDA is probably redundant at the end of this years homologation.
But the pipe design is around 40mm too short , due to the non retarding ignition curve , to keep peak power at 13800.
PM me for the 3D model port cores at Xmas time , but send a case of Opus One first , as a gift of course.

[wobbly]

Marc Marcelet has for sale a complete TFX engine real time data analysis setup.
It is here on FarceBook - https://www.facebook.com/groups/671081149638729/permalink/5124251020988364/
This was used to analyze a Vortex KF kart engine to help Neels refine the sim correlation to dyno data.
Contact me or Vortex on here if interested.

[Frits Overmars]

I think that is the crankcase pressure sensor? Or a sensor of some sort.You'd almost think they've given up TPI and switch to a cheaper system, maybe because TPI could not be made clean enough for the Euro 7 demands?
351202351203351204351206351205

[husaberg]

Interestingly all the engines 125-300 all use the same size throttle body......i could understand with a carb, but atomization shouldn't be an issue?

[husaberg]

.
Yea , but exactly the same amount of effort to build a 55Hp 125 cylinder as it is to build a 45 Hp one.

I totally disagree Wayne , nowhere near the same amount of effort was expended, these were brought off the shelf as opposed to being made.
Whilst i am sure to you and some other used to the finest and best. A 55 HP 125 sounds awesome and is the only option, as there is no class to race it in its a pretty limited market to sell to as 125 racing is deceased.

A 55 hp or 110hp 250 or 200hp plus 500 sure sounds great.but 2 stroke gp racing has unfortunately died.
i have no interst in superkarts or the pointy end of other karts
A 55hp 125 will also wear twice to 4x as fast as a 45-90twin -180 four hp and cost 4 times as much to maintain, hence that already tiny market just Shrunk further
Whereas a 90 HP RGV is a bit wider market (but still a tiny market) as is, the NZ bucket market or any other 2t market.
if someone wants something better, sure as shit they can modify them or spend 20 times or as you said a great stack of cash as much for something better.


Neil was awesome enough to offer to cast some cylinders so people could have some cheap cylinders to experiment with.
the first batch will be material cost plus whatever Neils costs are plus $100.
Personally see as the 2t world is so small and is shrinking daily i would have honestly expected a bit more support from a fellow kiwi.

https://img.newspapers.com/img/img?institutionId=0&user=0&id=269493228&clippingId=40102670&width=557&height=193&crop=1796_1577_781_276&rotation=0&ts=1629108847
That said i feel pretty confident it will give more hp than a Ryger.

[Flettner]

I totally disagree Wayne , nowhere near the same amount of effort was expended, these were brought off the shelf as opposed to being made.
Whilst i am sure to you and some other used to the finest and best. A 55 HP 125 sounds awesome and is the only option, as there is no class to race it in its a pretty limited market to sell to as 125 racing is deceased.

A 55 hp or 110hp 250 or 200hp plus 500 sure sounds great.but 2 stroke gp racing has unfortunately died.
i have no interst in superkarts or the pointy end of other karts
A 55hp 125 will also wear twice to 4x as fast as a 45-90twin -180 four hp and cost 4 times as much to maintain, hence that already tiny market just Shrunk further
Whereas a 90 HP RGV is a bit wider market (but still a tiny market) as is, the NZ bucket market or any other 2t market.
if someone wants something better, sure as shit they can modify them or spend 20 times or as you said a great stack of cash as much for something better.


Neil was awesome enough to offer to cast some cylinders so people could have some cheap cylinders to experiment with.
the first batch will be material cost plus whatever Neils costs are plus $100.
Personally see as the 2t world is so small and is shrinking daily i would have honestly expected a bit more support from a fellow kiwi.

https://img.newspapers.com/img/img?institutionId=0&user=0&id=269493228&clippingId=40102670&width=557&height=193&crop=1796_1577_781_276&rotation=0&ts=1629108847
That said i feel pretty confident it will give more hp than a Ryger.

Just how things roll, I guess.

[wobbly]

Real issue as i see it is that you are already behind the 8 ball.
The RGV type engine is 50.6 stroke by 56 bore and the patterns you have are for a 54 square.
Are you going to do all the calcs required to put all the ports in the correct place , as no matter what you do with jacking the new barrel up or down
then BDC is compromised as is the blowdown STA , the most important number in any engine.

Thus as this old Aprilia technology needs some pretty serious work to get it somewhere near right for an RGV application, I thought you might as well go ahead and update it to the later
spec as all the drawings are available on line.
And now we have TeeZee wanting something for a 110cc bucket and Neil wants 60 odd square - none of which are even close to what you have.

Maybe not as supportive as you would have expected , sorry , but realistic imho.

[Flettner]

Im no expert on twostroke development, far from it but what I do (and like) is the challange of manufactering cylinders, vairable rotary valve covers, fuel injection systems etc. Most times these parts will be not up to 'modern' spec, just how I see it.
Although I do 'look, listen and learn' my next lot of cylinders will be further up the spec range.

My first loop scavenge cylinder patterns, the 360, were designed and built 15 years ago, more intetested in just being able to cast my own at home. All they had to be was better than an F9 cylinder, I think they are.

I muddle along, I know my place.

We appreciate your free knowledge Wobbly and we do listen and learn.

[Muhr]

The next R2 is in CAD as we speak , so the R1 NDA is probably redundant at the end of this years homologation.
But the pipe design is around 40mm too short , due to the non retarding ignition curve , to keep peak power at 13800.
PM me for the 3D model port cores at Xmas time , but send a case of Opus One first , as a gift of course.


Real issue as i see it is that you are already behind the 8 ball.
The RGV type engine is 50.6 stroke by 56 bore and the patterns you have are for a 54 square.
Are you going to do all the calcs required to put all the ports in the correct place , as no matter what you do with jacking the new barrel up or down
then BDC is compromised as is the blowdown STA , the most important number in any engine.

Thus as this old Aprilia technology needs some pretty serious work to get it somewhere near right for an RGV application, I thought you might as well go ahead and update it to the later
spec as all the drawings are available on line.
And now we have TeeZee wanting something for a 110cc bucket and Neil wants 60 odd square - none of which are even close to what you have.

Maybe not as supportive as you would have expected , sorry , but realistic imho.

Is not that the case regardless of which cylinder they choose? TM does not look easier to change the bore and stroke.
What did you mean by 40mm to short pipe, is this the next one (r2) you are referring to?

[wobbly]

Muhr - The reference to the pipe length was that Ken asked about fitting a big ( 42mm ) carb and a proper ignition to the R1 for use in a road racing scenario.
If a modern ignition is fitted to the TM engine then all the development work done on the R1 pipe is out the window as its TL from the piston is around 760.
Whereas the 125 race pipes when fitted with a retarding ignition are around TL = 800 ( Aprilia - Honda A kit ) - simply due to the fact that with retard in the ignition the pipe average temp rises dramatically
with rpm , thus needing a 40mm longer pipe to keep peak Hp in the correct place.
The Aprilia made peak power at 13,000 and was not reved much to 14500 - The R1 makes peak power at 13800 and is reved to 14800 all day in karts , too high for any reliability when used
on a normal road racing circuit.

[husaberg]

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There are aftermarket 54mm cranks made for the RGV but they are a little spendy for most

RG250 vs RGv250 crank.
The RG250 was the earlier case reed parallel twin with a 54mm stroke.
credit goes to Vincent crabtree for all the grunt work

The crank center needs modifying from 2 main bearings to 1 so machining down with a nice wide roller bearing from a TZ350.
The other dimensions are identical.

https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1131048706&highlight=vincent+crabtree#post1131048706

https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130586696&highlight=vincent+crabtree#post1130586696

Pretty sure the RGV gearbox would be a bit iffy with 90 HP let alone 110hp

[jato]

Gearbox could be driven by a pair of straight-cut primary drive gears with a higher ratio - easier life for the gearbox and clutch plus no more side loading. relatively easy(ish) to build too so long as there is enough room for the bigger crank gear

[Muhr]

Muhr - The reference to the pipe length was that Ken asked about fitting a big ( 42mm ) carb and a proper ignition to the R1 for use in a road racing scenario.
If a modern ignition is fitted to the TM engine then all the development work done on the R1 pipe is out the window as its TL from the piston is around 760.
Whereas the 125 race pipes when fitted with a retarding ignition are around TL = 800 ( Aprilia - Honda A kit ) - simply due to the fact that with retard in the ignition the pipe average temp rises dramatically
with rpm , thus needing a 40mm longer pipe to keep peak Hp in the correct place.
The Aprilia made peak power at 13,000 and was not reved much to 14500 - The R1 makes peak power at 13800 and is reved to 14800 all day in karts , too high for any reliability when used
on a normal road racing circuit.

OK I understand!

I had imagined that the RSA was at 780 and 202 degrees. so average temp about 575m / s

[wobbly]

Nearly every Tubo pipe was 800 from the piston , and the duct roof was at 196* duration, the port radius started at 202* but using a 0.7mm x 5mm wide dead stopper blade bent at 45* = 1mm actual
height difference , it measured 198.
This is why when you do a STA analysis on the RSA it appears to have insufficient Blowdown , but the clever port radius increased the duct Cd so well that in reality the Blowdown flow
matched the Transfer power capability perfectly. Makes it hard for a single dimensional sim to replicate this correctly unless the radius effect on flow is factored into the code.

[F5 Dave]

Surely most engines have chamfers that vary from Conservative to pretty aggressive?

[wobbly]

F5 - Just like completely unnecessary chamfers on transfer ports , they reduce power.
Jans idea of putting a proper flow enhancing radius on the Exhaust ports timing edge was a piece of unadulterated genius.

[Tim Ey]

I have made a 54/107mm crank for the RGV250 / Aprilia RS250
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351223

The first one from the pictures was made by myself, with a primatist conrod. The next charge will be totally made by primatist. When we tested that on track, we will order some more. PM me if you are interested.

[monkeyfumi]

2 centre bearings, no centre seal?

[koenich]

While on the subject of EngMod files - does anyone have an input file for the Bidalot RF50WR cyl?

[Tim Ey]

2 centre bearings, no centre seal?

2 SKF bearings with seal covers & special grease filling. They are used in snowmobiles in the same application.
The seal covers work like a charm regarding sealing. Probably as airtight as a labyrinth seal...

[Frits Overmars]

It's friday june 3 in Thailand :drinknsin
351228

[Peter1962]

Proficiat met je verjaardag, Jan.


Happy birthday ! :drinknsin

[Javi]

Feliz cumpleaños MR Thiel.Muchos recordamos su gran trabajo con Ricardo Tormo,Bultaco y Derbi.Le deseo mucha salud.

[Muhr]

Nearly every Tubo pipe was 800 from the piston , and the duct roof was at 196* duration, the port radius started at 202* but using a 0.7mm x 5mm wide dead stopper blade bent at 45* = 1mm actual
height difference , it measured 198.
This is why when you do a STA analysis on the RSA it appears to have insufficient Blowdown , but the clever port radius increased the duct Cd so well that in reality the Blowdown flow
matched the Transfer power capability perfectly. Makes it hard for a single dimensional sim to replicate this correctly unless the radius effect on flow is factored into the code.

Thanks Wob
Just doing some tests now with r1 cylinder and programmable ignition. we'll see what length we end up with.

[TZ350]

.
2Stroke Stuffing. 2 x rotary valves in carbon fiber. https://youtu.be/eA62z-ib4VM

DIY Industrial grade CNC machine. https://youtu.be/cqYJS27aC4w

[pete376403]

.
2Stroke Stuffing. 2 x rotary valves in carbon fiber. https://youtu.be/eA62z-ib4VM

DIY Industrial grade CNC machine. https://youtu.be/cqYJS27aC4w

that CNC machine - just WOW!

[ceci]

I always thought that Alex's project was the most appropriate for it to be twin-cylinder, since from the first video I saw how he wasted twice as much fuel.

I am not the only one, the creator of the Bimota V2 500 engine, he has just been granted a patent in this regard "2022-04-20"

https://patentimages.storage.googleapis.com/bf/66/7f/fd1046c20b4ca5/imgf0001.png
https://patentimages.storage.googleapis.com/77/b8/fb/005220a7fc29e5/imgf0004.png

[ceci]

https://hypertec.it/wp-content/uploads/2021/11/1-1.jpg

https://hypertec.it/progettazione-di-un-motore-a-due-tempi-sperimentale/

https://patents.google.com/patent/EP3821115B1/en?inventor=Pierluigi+Marconi

Will it be the future?

[wobbly]

Doesn't seemed to have learned anything from the abject failure the VDue was with direct cylinder injection.
His design destroyed Bimota , who is paying for this.

[Brett S]

I know its modeled just for the patent, but the cylinder casting design could have been much prettier with gussets etc.

Will the top oil scraper directly connect the supercharged inlet port to the exhaust via the small oil scraper groove drain holes?

Is the electric assist motor the Novel part or is it's novelty all the past ideas in that specific combination?

[Flettner]

Why are we so hooked on loop scavenge?

[Grumph]

Is the electric assist motor the Novel part or is it's novelty all the past ideas in that specific combination?

That was my thought too. Very little there that wasn't done by DKW pre WW2.

[F5 Dave]

Why are we so hooked on loop scavenge?

Because it passes KISS.


I was originally trying to work a 'I have schnuerl idea' pun but it didn't look as good typed and I couldn't decide on how much to abbreviate.

[ken seeber]

Because it passes KISS.


I was originally trying to work a 'I have schnuerl idea' pun but it didn't look as good typed and I couldn't decide on how much to abbreviate.

Dave, Dave, Dave, it's ASS…..Another Schnurle System..:clap::clap:

[ceci]

Doesn't seemed to have learned anything from the abject failure the VDue was with direct cylinder injection.
His design destroyed Bimota , who is paying for this.

It may be the third time the definitive one, Bimota, Gas Gas and now this
In the patent there is hardly anything new, that we have not seen in other projects, if the one that is V-twin and direct injection

https://www.mtu.edu/unscripted/2021/09/images/revolution-johnktherev--dsc-1502-banner1200.jpg

[Flettner]

How is OP uniflow not KISS?
No worse than any twin cylinder loop scavenge, two single cylinder cranks, no heads, crank joining gears can be clutch gear water pump gear etc, no balance shaft needed ... and is rated as a single cylinder. One combustion chamber. Standard crankcase charging. Exhaust throttling, jetfire ignition.

And a side benifit, the cylinder is priced as a single cylinder for plating.

[ceci]

How is OP uniflow not KISS?
No worse than any twin cylinder loop scavenge, two single cylinder cranks, no heads, crank joining gears can be clutch gear water pump gear etc, no balance shaft needed ... and is rated as a single cylinder. One combustion chamber. Standard crankcase charging. Exhaust throttling, jetfire ignition.

And a side benifit, the cylinder is priced as a single cylinder for plating.


Your wonderful words about the OP Uniflow mechanism, have led me to wonder why the 1951 piaggio OP engine was not commercialized (I have a lot of love for vespas, because it was the first motorcycle I got on, in my childhood my brother and I played with the one my father had before buying the first car, the reason for buying the car was my arrival since the family increased to 3 children and my mother did not have as many arms to hold us, leading to the abandonment of the scooter in the patio where years later my brother and I used to play with her pushing each other).

I think I found the answer in my memories too, at the beginning of my youth I was lucky enough to be able to disassemble an engine that they had given us to make us a kart, the engine in question was the ISO of Italian origin, Uniflow two-cylinder, this engine allowed me see how the non-asymmetrical system works, it is not an OP engine, but it works the same.

My conclusion is that the basic rule of two stroke was imposed, which is the same as the famous Ockham's razor

[Condyn]

351321

Prepared and ready to test a batch of pipes I built at an eddy current engine dyno. All four sets of pipes have the same tuned length from piston to end of convergent cone and share the same dwell and convergent cones, thus all four also carry 66 % end of diffuser and 77 % end of dwell. Two sets have 33.5 % headers and two sets have 31.5 % headers. Two sets have two stage diffusers and two sets have three stage diffusers. I have added provisions for tophat nozzles to Optimize the bleed orfice. In hind sight there are things I would have done differently for this test, but I believe I will take home a lot of usable data.
Now I just hope the 75 % exhaust chordal width keeps the ring in. I have had great results with such wide ports in the past, however this was the last time I will ever send a cylinder to millennium. Royal disaster of a chamfer job, completely changing the geometry, even after I left them several notes with my instructions.

[HenkS]

75% cord wide don't need to be a problem, when executed correctly.
Several years used 74.5%, never broke rings.
Power gain is more than 5%

[PVO]

I went to this in 2020 and it was pretty good. Program details and schedule provided at this link:

http://di2-stroke-engine.ifp-school.com/

If you can't attend the presentations are usually posted online afterward.

[Peter1962]

I went to this in 2020 and it was pretty good. Program details and schedule provided at this link:

http://di2-stroke-engine.ifp-school.com/

If you can't attend the presentations are usually posted online afterward.


Opposed piston 2 stroke engines could be a very interesting topic, the other topics not so much...

[Niels Abildgaard]

I went to this in 2020 and it was pretty good. Program details and schedule provided at this link:

http://di2-stroke-engine.ifp-school.com/

If you can't attend the presentations are usually posted online afterward.

I would love to go but am to old.
Can You please give link to procedings of 2018 and 2020?

[Haufen]

I would love to go but am to old.
Can You please give link to procedings of 2018 and 2020?

If you follow his link and then scoll to the very bottom of the page, there are some links to the proceedings of 2018 and 2020.

Anyone going this year?

[Niels Abildgaard]

If you follow his link and then scoll to the very bottom of the page, there are some links to the proceedings of 2018 and 2020.



I have found them thank You and have seen that the two radical innovations are 0pp0sed piston engines with electric generators instead of gears for power take off and sidevalved two stroke engines.
The OP elecsyn was demonstrated by me around 1994 and the sidevalve thing schemed first by me around 2015.Innovators do not get rich and rewarded but it is quite nice to feel smarter than the average.

[WilDun]

Your wonderful words about the OP Uniflow mechanism, have led me to wonder why the 1951 piaggio OP engine was not commercialized .........

I don't call in here much these days! -

I think that the opposed piston engine is not really viable in a motorcycle in the form of single cylinder, (being a little awkward to fit in a frame, - it seemed to fit ok in the Vespa speed record type frame. .......
I know that Neil's Hintz's experiment is a single cylinder because it is just that (an experiment)! - But it is a well known fact that if it eventually becomes a 3cylinder (6 pistons) it then becomes a much more compact engine to deal with! (and I'm told that with 3 exhausts going into one pipe there will be further benefits!). - Just a thought!

Congrats on your futuristic thoughts on engine design Niels Abildgaard!

[ceci]

I don't call in here much these days! -

I think that the opposed piston engine is not really viable in a motorcycle in the form of single cylinder, (being a little awkward to fit in a frame, - it seemed to fit ok in the Vespa speed record type frame. .......


I don't think it was due to space in the chassis, I think it was due to price "the Vespa engine that I have always known is simple and cheap" the one with the record, it is the opposite.

This is another approach: a manufacturer has to manufacture the technology that he is capable of doing, or the one that his clientele is capable of buying.

[WilDun]

I don't think it was due to space in the chassis, I think it was due to price "the Vespa engine that I have always known is simple and cheap" the one with the record, it is the opposite.

This is another approach: a manufacturer has to manufacture the technology that he is capable of doing, or the one that his clientele is capable of buying.

To be honest, I think that the buying public is swayed more by fashion than anything else! - the most important thing to them is how many "accessories" they have fitted (or have got someone else to fit for them!) - what the engine is all about, escapes them!.

[ceci]

To be honest, I think that the buying public is swayed more by fashion than anything else! - the most important thing to them is how many "accessories" they have fitted (or have got someone else to fit for them!) - what the engine is all about, escapes them!.

Do you think that they would sell 80,000 units between the Bimota VDue, Suter and Vins, as if Vespa did it with its 150 GS (VS5) model between 1958 - 1961.

True technology is the one that reaches everyone, not a privileged few

[WilDun]

Do you think that they would sell 80,000 units between the Bimota VDue, Suter and Vins, as if Vespa did it with its 150 GS (VS5) model between 1958 - 1961.

True technology is the one that reaches everyone, not a privileged few

No, but times were different then, - recovering from war, need for cheap transport, engine design not a consideration, just something to get around on and attract attention - my Vespa's better than your's, no it's not! etc. - V-Due, Suter, etc - very interesting to the likes of us of course, but overpriced, in danger of being legislated off the planet - grasping at the last remaining straws! - now forcibly being wiped out by electrics, just as the extremely interesting piston aero engines developed during and after WW2 were - potentially successful designs, but wiped out and relegated to history by gas turbines!
Long may the interest in two strokes last here! but fewer and fewer engines available anymore for Buckets!
So people (like some on here) now producing their own!
:niceone:

[Larry Wiechman]

The opposed piston configuration would be wonderful for a diesel. What ignition scheme for spark ignition? A series of radial, pre-chamber flame jets?

[Flettner]

To be honest, I think that the buying public is swayed more by fashion than anything else! - the most important thing to them is how many "accessories" they have fitted (or have got someone else to fit for them!) - what the engine is all about, escapes them!.


The opposed piston configuration would be wonderful for a diesel. What ignition scheme for spark ignition? A series of radial, pre-chamber flame jets?

Haha, have you been lurking around my workshop. Three plugs in three chambers. If thats not a go I have a second more cunning scheme.

Im not keen on diesel.

Uniflow cost, complexity?
Carburetors, cheap.
Single cylinder, plated as such.
Crankshafts, yes two, but smaller ones and they eliminate the need for a balance shaft. It could be reasoned that the second crank is a balance shaft.
An OP 175cc is not twice the length of a single cylinder loop scavenge 175cc. Including the sparkplug on a loop scavenge engine there is not much in it.
Crank joining gears are already in the average twostroke bike engine, the cost of the cylinder head? There isn't one so no, nothing extra.

Where is the extra cost?

[lohring]

The opposed piston configuration would be wonderful for a diesel. What ignition scheme for spark ignition? A series of radial, pre-chamber flame jets?

The original successful OP engine was the Junkers diesel (https://en.wikipedia.org/wiki/Junkers_Jumo_204). Fairbanks Morse (https://en.wikipedia.org/wiki/Fairbanks_Morse_38_8-1/8_diesel_engine) made an opposed piston engine for railroad engine use. Today Cummins (https://www.greencarcongress.com/2021/08/20210803-ace.html) is investigating the Achetes engine (https://achatespower.com/) for various applications. Below is the ignition concept for a gasoline opposed piston engine. The concept is alive and well.

Lohring Miller

351356351357351358

[Peter1962]

Haha, have you been lurking around my workshop. Three plugs in three chambers. If thats not a go I have a second more cunning scheme.

Im not keen on diesel.

Uniflow cost, complexity?
Carburetors, cheap.
Single cylinder, plated as such.
Crankshafts, yes two, but smaller ones and they eliminate the need for a balance shaft. It could be reasoned that the second crank is a balance shaft.
An OP 175cc is not twice the length of a single cylinder loop scavenge 175cc. Including the sparkplug on a loop scavenge engine there is not much in it.
Crank joining gears are already in the average twostroke bike engine, the cost of the cylinder head? There isn't one so no, nothing extra.

Where is the extra cost?

Neil, do you think it would be a viable plan to make a 'kit' OP for a mass produced two stroke mono like the 250 or 300cc KTM SX, XC or XCW series ? That is a big market, more 300cc enduro 2 strokes are sold than 450 4 strokes.

[Larry Wiechman]

[QUOTE=lohring;1131203138]The original successful OP engine was the Junkers diesel (https://en.wikipedia.org/wiki/Junkers_Jumo_204). Fairbanks Morse (https://en.wikipedia.org/wiki/Fairbanks_Morse_38_8-1/8_diesel_engine) made an opposed piston engine for railroad engine use.

Lohring Miller

The Fairbanks-Morse factory in Beloit, Wisconsin is 5 miles from my home. I'll see if I can find a talkative engineer.

[Niels Abildgaard]

http://chevy57.free.fr/FORUM/junkers_two-stroke_crosshead.gif

[Flettner]

http://chevy57.free.fr/FORUM/junkers_two-stroke_crosshead.gif

Very nice but not practical on a 175cc off road bike.

[Flettner]

Neil, do you think it would be a viable plan to make a 'kit' OP for a mass produced two stroke mono like the 250 or 300cc KTM SX, XC or XCW series ? That is a big market, more 300cc enduro 2 strokes are sold than 450 4 strokes.

Totally but I can't with my meager resources.
The plan is to run this 175, in a bike, sort out the details as it is, a stand up engine. If I can get acceptable results Ill build a second engine but laying down, a compact version.
The idea is to have a running working rideable bike, or I dont consider it a success. Not just petty pictures. After that??? The world seems to want electric I guess now.

[Flettner]

A line up of cylinders off to heat treatments. More on the way soon, note the 175cc OP uniflow cylinder casting is also now a workable unit.

[wobbly]

No Neil " the world " doesn't want electric.
We are being continually force fed an insidious party line of complete bullshit about an EVs environmental impacts that has no basis in actual reality.
Apart from the huge impact of the millions of tons of mined rare earth metals needed to actually make the batteries ( just another finite resource ) , and some of the dirtyest manufacturing processes of any current industry ,
the vast majority of EVs power consumed around the world, is supplied via coal and or gas.

Here in NZ the situation is even stupider , we cant keep up the current grid supply ( minimal EV usage ) without spending millions of overseas funds on imported crap coal from Asia to power Huntly, when there is some of
the best cleanest coal just down the road . That's why it was built there.

But our lip service " green " virtue signaling govt has banned its use. How could they possibly " save the planet " when they are completely off it most of the time.
How the hell is our infrastructure going to cope with hundreds of thousands of extra KwH being pumped into cars continuously.
End of off topic rant , sorry.

[Flettner]

No Neil " the world " doesn't want electric.
We are being continually force fed an insidious party line of complete bullshit about an EVs environmental impacts that has no basis in actual reality.
Apart from the huge impact of the millions of tons of mined rare earth metals needed to actually make the batteries ( just another finite resource ) , and some of the dirtyest manufacturing processes of any current industry ,
the vast majority of EVs power consumed around the world, is supplied via coal and or gas.

Here in NZ the situation is even stupider , we cant keep up the current grid supply ( minimal EV usage ) without spending millions of overseas funds on imported crap coal from Asia to power Huntly, when there is some of
the best cleanest coal just down the road . That's why it was built there.

But our lip service " green " virtue signaling govt has banned its use. How could they possibly " save the planet " when they are completely off it most of the time.
How the hell is our infrastructure going to cope with hundreds of thousands of extra KwH being pumped into cars continuously.
End of off topic rant , sorry.

Tell that to the MX crowd. This new Stark Varg MX bike is supposed to be the berries, according to many MX threads. Never mind that they will all need to take petrol generators to keep them running for an event. But its what customers think they want now, whatever the reason. I dont know but I would have thought you would be better off just putting the petrol straight into your bike? More efficent? I get a little sick of the hype and bullshit.
Google the Jetson 1, same advertising crap, and people belive it. ??? $95,000.00 USD and it wont even fly with me in it. Very limited range and unlike an autogyro / helicopter, in the event of power failure, your fucked.

Dont get me wrong, Im not against "green" technolagy....

[41juergen]

No Neil " the world " doesn't want electric.
We are being continually force fed an insidious party line of complete bullshit about an EVs environmental impacts that has no basis in actual reality.
Apart from the huge impact of the millions of tons of mined rare earth metals needed to actually make the batteries ( just another finite resource ) , and some of the dirtyest manufacturing processes of any current industry ,
the vast majority of EVs power consumed around the world, is supplied via coal and or gas.

Here in NZ the situation is even stupider , we cant keep up the current grid supply ( minimal EV usage ) without spending millions of overseas funds on imported crap coal from Asia to power Huntly, when there is some of
the best cleanest coal just down the road . That's why it was built there.

But our lip service " green " virtue signaling govt has banned its use. How could they possibly " save the planet " when they are completely off it most of the time.
How the hell is our infrastructure going to cope with hundreds of thousands of extra KwH being pumped into cars continuously.
End of off topic rant , sorry.

So here in Germany it is quite simple: the politicians tell us that we have to build up solar cells on our houses and need to feed our cars with that power. For me it is still not yet clear how that shall be done in a 1 mio people city with that limited space... :laugh:
And a friend of mine is not allowed to put his potential new hybrid car in the garage in the basement, as they are affraid of getting a fire what will burn down a 140 family department house... The politicans say, he shall use the public transportation!:bleh:
OK, may be I'm influenced on that discussion because I work in the automotive industry for combustion engines, but I think it would be better to use the green fuel setup.

[Flettner]

OK, may be I'm influenced on that discussion because I work in the automotive industry for combustion engines, but I think it would be better to use the green fuel setup.

Totaly......

[WilDun]

http://chevy57.free.fr/FORUM/junkers_two-stroke_crosshead.gif

Neils, I believe (obviously like you) that the piston should not have to bear the weight of the side thrust - that should be taken up by a fully lubricated crosshead, relieving the piston and allowing it to operate with very little lubrication!

[WilDun]

No Neil " the world " doesn't want electric. ..........

End of off topic rant , sorry.

Typical, - up here,(Ak.) they are building dozens of 3-4 storey units on all the old quarter acre sites, - nowhere to park cars etc etc and won't be fixed till well after they have built these! (all ass about face!).
Same with electrification of vehicles, the power supplies soon won't be able to cope and what's the betting they will be offered cheap Nuclear Plants (with plenty of assurances regarding safety) and putting them on these "Shaky Isles" ! - also, they are selling them (EV's) by pointing out just how cheap it is to operate them (that's at today's electricity prices!) - watch electricity prices SOAR!

[lohring]

Sorry to get this thread even more off topic, but I've had some experience with electric power since 2008. Our 100 mph electric hydro (https://www.youtube.com/watch?v=-yNu2_LlO9s&list=FLKa7H9pgwmzbufG9sD23_FQ&index=19&t=11s) had a lot of batteries to charge. Two big gasoline generators barely supplied enough power to charge the batteries in an hour. Even so it set a 98+ mph kilo record that still stands, but wasn't green in any sense. Ten years later I bought an electric car after 60 years of owning various gas and diesel cars. I bought it for performance, not to save the world. It hasn't been a disappointment. It takes a different way of thinking about how to operate a car. It's more like a smart phone. I need to run on Autopilot most of the time on my commute to avoid becoming friends with the state police. It's still fun to accelerate from 45 to over 90 mph in the length of a semi while passing. Test drive one of the higher performance versions and see what I mean. They aren't gulf carts.

Lohring Miller

351363351364351365

[Flettner]

Neils, I believe (obviously like you) that the piston should not have to bear the weight of the side thrust - that should be taken up by a fully lubricated crosshead, relieving the piston and allowing it to operate with very little lubrication!

Dont need a cross head.
No doubt, he who makes the most electric power will win, how ever its used, direct to battery or used to make ethanol / synthetic liquid fuel.
https://youtube.com/shorts/-2AhNvDFNlQ?feature=share

[TZ350]

351367

I recently converted my ignition system to 12Volt total loss. DC power to the Ignitec and temperature gauge.
And now I have two problems.
The temperature gauge goes blank after a short while running and the engine has periodic fits of running like a bag of poo.

So I put an oscilloscope across the DC supply lines. In a perfect world it would display a dead flat line but mine has spikes on it when the engine is running.
There is significant noise on the positive DC supply???

Fitting an 18Volt battery, DC-DC 12Volt converter and 2,200uF capacitor did not help. Nor did just running the 18Volt battery with the capacitor alone and then just the 18Volt battery. Non of this helped.

I did not have this problem when I was running an alternator, 12Volt DC rectifier regulator and capacitor. Which is the standard "push and go" setup.

[TZ350]

351369

2Stroke Stuffing is starting to get enough reliability to be able to start doing un interrupted dyno runs so he can concentrate on tuning adjustments:- https://youtu.be/4Ikt2SIeoic

[WilDun]

Dont need a cross head...........

How dare you disagree with me! - well, I guess that we won't even need a piston soon! (all compulsory EV remember!) :rolleyes:

[wobbly]

Anyone got an RZ350 cylinder lying about I could use to do some measuring for a project.

[ken seeber]

Not to labour the electric argument, but gotta agree with Lohring re the electric car driving pleasure. Fortunate to be able to charge it at home with solar and it’s generally great.

However, must also agree with many points made here about the stupidity and futility of trying to aggressively force going electric in conjunction with the negative stance on coal, gas and oil production.

What have electric cars and 2 strokes have in common??? NO SUMP..

[F5 Dave]

Anyone got an RZ350 cylinder lying about I could use to do some measuring for a project.
Not std, and I couldn't tell you what as I didn't do it. Do want back thou if useful.

[Hoebra]

Next week I`m going to make some tests with Nitromethan as fuel. Its 50% Nitro Concentration. Has anybody some good advices?
All areas wich are passes by fuel need to be bigger to match the new AFR. Ignition needs to be retarded, cause Nitromethan burns faster. The end diameter of the rearcone will be increased an later sized down slowly. What about combustion ratio? On gasolin the engine liked 13,5-13,8:1 most, higher lost power again. By energy round about 50% more power than 102Ultimate should be possible, if I reach 30%+ I`m happy, the 11% on E85 wasn`t enough. Is there a need of another heatrange of the sparkplug or something like that?

[TZ350]

Next week I`m going to make some tests with Nitromethan as fuel. Its 50% Nitro Concentration.

If I was thinking about running 50% Nitro-methane and a Carburetor on a two stroke. I would keep the carburetor as original, correctly jetted for petrol (or whatever fuel you have been using) and drop raw Nitro (100%) in through a solenoid power jet. Or better yet pump it into the inlet with a small peristaltic pump. We tried this on the dyno. Pumped raw nitro into the carb bell-mouth. Some changes to the ignition at peak torque required but it worked great. It means two tanks, one for petrol the other for nitro.

This works because Nitro carries slightly more fuel than oxygen. Nitro by itself as a fuel, very rich mixtures are required for the small amount of surplus fuel in the Nitro to be at the correct air/fuel ratio with the inducted air other wise it runs lean. And you don't want to know Nitro when its lean.

But if you already have a correct air/fuel ratio running the original carb on petrol (or whatever) then all the extra Nitro does, is add oxygen and its own fuel at the perfectly correct air/fuel ratio for itself with a little bit of its own fuel left over to add some enriching of the original base petrol air/fuel ratio.

[wobbly]

My suggestion is that Nitro is way, way more effective if used as am additive to a fuel system and engine tune that has been optimized for Methanol already.
This primarily involves a big jump in compression and a pipe tuned to the much lower Exhaust gas temp/wave speed that will be created by a rich (+ 20 % over stochiometric ) fuel curve.
The two are very much synergistic in action , whereas petrol/ Nitro is just a simplistic approach with nowhere near the possible capabilities.
Its like sticking nitros in a stock Avenger Vs a stock Aventador.

[andreas]

Anyone got an RZ350 cylinder lying about I could use to do some measuring for a project.

Got a 1UA, not the 31K, been heavily modified, though some still there. Should find relevant measures here; https://www.rd350lc.net/

[SwePatrick]

Ignition needs to be retarded, cause Nitromethan burns faster.

I would say it´s the other way around, it burns REALLY slow, you need to advance a LOT.
Nitro topfuel dragsters are having ignition point about 58-65degree before top dead center.
And those are supercharged, hence a more compressed media, and a more compressed media burns faster than a less compressed media.
Thus you need to advance ignition even more then they do.

But!
Consider they run ~97% nitro, so you might get away with ~25-35 degree before tdc.

You might also want to try a surface discharge sparkplug(no groundstrap)

[husaberg]

351384
http://3cyl.com/mraxl/manuals/bell/performance-tuning-graham-bell.pdf
i remembered after reading that that the top fuel dragsters used propylene oxide also to speed up combustion.
its apparently banned now, Cancer causing i think.

All this talk of methanol does raise a thought can you make the stinger bleed venturi considerably smaller when running methanol or ethanol?

something old something well new to me....
351385
https://www.thumpertalk.com/forums/topic/750322-74-honda-cr-125-with-mr-175-cylinderhead/
Am i wrong or is this braided oil line?

that said
https://www.flexiducting.co.nz/products/flexible-exhaust-pipe/
20mm up

[Frits Overmars]

All this talk of methanol does raise a thought can you make the stinger bleed venturi considerably smaller when running methanol or ethanol?No. The restrictor diameter depends on the power produced by the engine, not on the type of fuel. But why do you ask Husa? I am curious about your line of thought.

[husaberg]

No. The restrictor diameter depends on the power produced by the engine, not on the type of fuel. But why do you ask Husa? I am curious about your line of thought.
In the old days we were lead to believe the smaller the bleed the more hp, with a caveat of but go too small and you create too much heat.
its likely a fallacy. I have always just run the recommended sizes. But never melted anything either

[lohring]

I believe the most highly developed nitro burning 2 strokes are model race engines. Today their popularity has declined against competition from industrial gasoline and electric power. To help preserve this history, I wrote a 6 part series. Readers will discover that I shamelessly stole material from members on this site as well as my friend, the late Jim Allen.

Lohring Miller

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[lohring]

351400351401

[Condyn]

351321

Prepared and ready to test a batch of pipes I built at an eddy current engine dyno. All four sets of pipes have the same tuned length from piston to end of convergent cone and share the same dwell and convergent cones, thus all four also carry 66 % end of diffuser and 77 % end of dwell. Two sets have 33.5 % headers and two sets have 31.5 % headers. Two sets have two stage diffusers and two sets have three stage diffusers. I have added provisions for tophat nozzles to Optimize the bleed orfice. In hind sight there are things I would have done differently for this test, but I believe I will take home a lot of usable data.
Now I just hope the 75 % exhaust chordal width keeps the ring in. I have had great results with such wide ports in the past, however this was the last time I will ever send a cylinder to millennium. Royal disaster of a chamfer job, completely changing the geometry, even after I left them several notes with my instructions.

Well the eddy current engine dyno day went very well in my opinion. An honest 10% increase in power from last year. The engine is maxed out on every facet besides lowering the intake port another 2 degrees. The (considered to be unsafe) 75.5% exhaust port held the ring without incident, and the ring end gap that rides right on the chamfer of the B ports survived. (Maybe it was a blessing that millenium chamfered my transfers after all)

Best of all, Engmod2t and my dyno results are all within .75 Hp for most of the curve with very small discrepancies that are probably a byproduct of small modeling errors. I had to do some tweaking to the temperature files from the default values, but after the first pipe was ran in the sim, the other 3 followed the trend and were an accurate representation of the dyno testing.

We did multiple dyno runs on each pipe to verify consistency. Since this is for short duration drag racing each pipe also received what we called a cold test and a hot test. We placed a K type thermocouple in the center section of each pipe so we could heat the pipes to a consistent starting temperature before the controlled auto-run was started.

Something that I noticed that I do not fully understand. The pipes made more hp throughout the graph on the cold start test, however the entire curve shifted to the right when performing a hot test pipe. The hot start pipes also smoothed out the curve much better.

Here is my question. And I ask this cautiously because I now know that I am out to lunch on my pipe designs from where the end power goal is. The peak rpm is 3-400 rpm lower than expected, and what the engine wants.
-I have been been under the impression for a while now that the hotter a pipe is the shorter it thinks it is, makes sense the power moved to the right on the hot start pipes. Why is power down with the hot pipe then? Confused I am.

[Vannik]

Here is my question. And I ask this cautiously because I now know that I am out to lunch on my pipe designs from where the end power goal is. The peak rpm is 3-400 rpm lower than expected, and what the engine wants.
-I have been been under the impression for a while now that the hotter a pipe is the shorter it thinks it is, makes sense the power moved to the right on the hot start pipes. Why is power down with the hot pipe then? Confused I am.

Very often it is not the hotter pipe but the hotter exhaust port wall that heats up the short circuited / over scavenged gas that is plugged back into the cylinder by the plugging pulse, this has a lower density and thus less mass in the cylinder at export closure.

[Condyn]

Thank you, that is enough to put my wandering mind at ease.

[Haufen]

-I have been been under the impression for a while now that the hotter a pipe is the shorter it thinks it is, makes sense the power moved to the right on the hot start pipes. Why is power down with the hot pipe then? Confused I am.

To verify if your engine is running out of breath at higher rpm or if you are seeing the effect of the then fully warmed up engine, you can build a shorter version of that same pipe and do another cold and hot dyno pull. You should be able to model the temperature effect in EngMod, too if you play around with the temperatures a bit. On air cooled engines, the temperature and thus power differences between a cold and a hot engine are much bigger than on watercooled engines. Do you happen to have a thermocouple or an infrared gauge to measure the crankcase temperature?

[Condyn]

To verify if your engine is running out of breath at higher rpm or if you are seeing the effect of the then fully warmed up engine, you can build a shorter version of that same pipe and do another cold and hot dyno pull. You should be able to model the temperature effect in EngMod, too if you play around with the temperatures a bit. On air cooled engines, the temperature and thus power differences between a cold and a hot engine are much bigger than on watercooled engines. Do you happen to have a thermocouple or an infrared gauge to measure the crankcase temperature?

Thank you for the reply. I do not believe the engine is running out of breath just based on comparable setups that I am familiar with. I do not currently have any crankcase temperature monitoring, but I do have a spare thermocouple that I could fix to the case.

[wobbly]

Frits is right again. The nozzle size is dependent on the engine power , with one caveat.
A bigger nozzle reduces the pipe pressure and thus the operating efficiency.
This works in your favor lower in the powerband , as the return wave coming back too early has a reduced amplitude , thus it doesn't fuckup the power so badly.
But of course no free lunch , in that what you gain down low you loose up top.

Re the pipe temp and power loss - if the hotter pipe moves the power to the right ( as it should ) but you are seeing a loss at the higher rpm, then that means one of two things.
There is an element of the tune that is not suited to the higher rpm , or the pipe is wrong for the new higher rpm ( or both ).
EngMod is superb at sorting this stuff out.

Maybe you need to settle on a strict test procedure that will then be taken to the strip , such that the beginning pipe/case temp is always the same.
I did this years ago when designing pipes for Yamaha KT100 , the case temp was always started at the same level , and the final egt was always adjusted to match after every dyno run.
Case and head temp are critical on an aircooled and can really lead you off on useless tangents if the process of testing isnt rigorous.

[Condyn]

Thanks Wobbly. Done deal. I’ll get something consistent figured out. Admittedly, we pulled the under plug thermocouples off after the first pipe so although the pipe starting temps were consistently tested throughout the dyno runs, the cylinders/heads were a “go feel them” thing, which is obviously not super accurate.

[TZ350]

.
If you are running lots of Methanol and some Nitro in a two stroke dragster. In my opinion EFI is the way to go.
Simply because it is much easier to deliver the volume of fuel required and you have much more precise control over fuel delivery.

The interview in this clip https://youtu.be/eRItqiCFuQE shows a very fast injected H2 Kawasaki dragster.

[SwePatrick]

No. The restrictor diameter depends on the power produced by the engine, not on the type of fuel. But why do you ask Husa? I am curious about your line of thought.

In line wth my experiances.

Some more info for the guy going over to meth from petrol:
I have found that one can often make the restriction a little bit larger than calculated when running meth.
This i guess keeps things under control when trying to max out a meth engine(temprature control)
And i have learned that methengines delivers the best around 430-450c exhaust temp(three piston diams from piston)
Thereby one need to calculate with that exhaust temp when designing the pipe.

[Frits Overmars]

The (considered to be unsafe) 75.5% exhaust port held the ring without incidentConsidered unsafe by whom? Not by me. 75,5% need not be unsafe, provided that the corner radii are large enough. But the minimum safe radii for a port width of more than 70% of the bore will reduce the blowdown area at the upper part of the port (the yellow areas in the picture), where it counts most because that is the area that is open for the longest time. A port width of 70% of the bore is not the maximum width; it is the optimum width.


Best of all, Engmod2t and my dyno results are all within .75 HpI could not find the total power figure you quoted for that engine, which left me wondering how good or how bad this 0,75 HP difference is.
Is it 0,1% , 1%, 10% or 50% of the engine power? Percentages often give a better impression than just raw values.

[Condyn]

Considered unsafe by whom? Not by me. 75,5% need not be unsafe, provided that the corner radii are large enough. But the minimum safe radii for a port width of more than 70% of the bore will reduce the blowdown area at the upper part of the port (the yellow areas in the picture), where it counts most because that is the area that is open for the longest time. A port width of 70% of the bore is not the maximum width; it is the optimum width.



I could not find the total power figure you quoted for that engine, which left me wondering how good or how bad this 0,75 HP difference is.
Is it 0,1% , 1%, 10% or 50% of the engine power? Percentages often give a better impression than just raw values.

Pardon my ignorance to the 70% rule Frits. The TIME part of the phrase specific time/area sometimes slips my grasp. I will have to do some experimenting with the OPTIMUM port shape and compare the results.

My Engmod2t data is within 1% of the real life eddy current engine dyno data. Just the same as real world testing, the temperatures in engmod2t play a major roll in the measured outcome. I am slowly learning the level of influence that heat has in engines.

[jonny quest]

You can make an ex port 78% I may have even run 82% non bridged.
But roof edge must have a nice opening radius. And don't widen port much after transfer opening. Shape it like a bridged port.

[wobbly]

The traditionally accepted " rule" for the Exhaust port was 72% - this was used by Yamaha for decades in the RD based TZ range of customer race engines.
But these had very generous corner rads that , as Frits drawing shows , restricts the Blowdown area available.

I worked on a set of later model 4DP TZ cylinders ( 56 bore ) a while ago that had been " tuned " by a famous ex Roberts tech.
The Exhausts had ben widened to 75% with no change to the radi.
The owner wasnt overly thrilled when after the initial dyno runs , and two practice sessions , the new pistons timing edges were obviously belted to shit , and the rings were on the verge of trapping due to mental piston rock.

Angle area as a port metric has been also used for years , but imho , this metric when combined with rpm , that describes a ports effective open area and how long that area is available at a specific
engine speed ( STA ) , combines all of the data into a useful one for predicting power capability at a chosen rpm.

EDIT - added info. In a water cooled 125 race engine the power drop from running at 65*C exit temp Vs 45*C is 1.5 Hp in near 50.

[jonny quest]

I should mention the 78% ex port was on a snowmobile. 200deg ex 132trans (ex had height room above transfers) and only 8000rpm.

We would do this on our drag sleds. I did it on my personal trail sled... rode it 3 months no issues.

Rpm is a big factor in ring/piston life. 192ex 130trans not much room for good safe 78% shape

[diesel pig]

This exhaust port edge radius and no camber on the transfer ports edges for good power and long mechanical life is fascinating to me. Before I spend a significant amount of time searching this thread on this subject has some one done a detailed post about this?

[Hoebra]

A short report of the Nitromethan/Methanol test:

There where some thougts before the beginning, based von calculations Frits published some time ago. Fore some chemical/physical data you find different Numbers on different sources, but all of them are nearby, so I used the following:

Air Fuel Ratio:

Petrol: 14,7:1
Ethanol: 8,4:1
Methanol: 6,52:1
Nitromethan: 1,8:1

I`m not quite shure whats the right translation for "Heizwert", so I call it "energy potential":

Petrol 43600 kJ/kg
Etanol 26800 kJ/kg
Methanol 20100 kJ/kg
Nitromethan 12100 kJ/kg

At first we wanted to know wich AFR we would have to use. So a 50%/50% Concentration of Nitromethan/Methanol would be:

0,5*6,52+0,5*1,8= 4,16

In relation to petrol you need 14,7:4,16= 3,533 times the mass of NM/M to burn a fix amount of Air then you need with petrol.

The energy potential would be:

0,5* 20100 kJ/kg + 0,5* 12100 kJ/kg = 16100 kJ/kg

And becaus you need 3,533 times more of it its: 3,533*16100 = 56881 kJ/kg

Compared to petrols 43600kJ/kg ist 30% more Energy paired to the same amount of air sucked in the engine. So roundabout 30% more power should be possible.


But 1kg Fluid isn`t 1l:

1kg petrol = 1,389l
1kg Ethanol= 1,267l
1kg Methanol = 1,266l
1kg Nitromethan = 0,877l

so 1kg 50/50 NM/M is:

0,5*0,877l+0,5*1,266l= 1,0715l

3,533*1,0715l= 3,785l

Compared to petrol its 3,785/1,389= 2,725 times the volume.

Based on Frits a Racing twostrokes needs 7ccm/PS/min petrol.

So we would need (2,725*7ccm)/1,3PS/min = 14,67ccm NM/M /PS/min

I`m aiming for 33/34 crank hp, cause at the Moment we got about 26 on petrol. That means: 14,67*34= 498ccm/min.

We are using selfmade carburators, based on Lectron principle, but with seperate Fuel Chamber and smoothebore. Because of the seperate Fuelchamber there are no vibration issues and the rotary Inlet likes the shortness alot:

351411

351412

351413

In Need of the great Number of Metering Rods you need for different engines/carb sizes/fuels we started to grind them ourselves.

So I calculated the needed Area in Relation to Petrol/E85 and grinded some rods:

351414

Its the calculated rod and 2 wich are leander and richer in 1/10mm steps, big differences, but there is still a Powerjetsystem.

today we could do some first testing:

therefore I removed the Stinger reduction complety (now 17,8mm) an retarded Ignition from 14 to 10° flatline. The Powerjet System on our carburator I jetted from 60/100mm to 120.

The engine starts great an idles realy good, in the beginning it was a little lean on idle, but taking the rod higher solved the problem. At the moment there is no choke system, so if you try to rev agressivly in the first seconds the enginge will die, but waiting some seconds maybee 20 seconds solves it, the enginge becomes richer an reves.
When it was to lean he bulked quite a times out of the carb, now richer this is gone.
Up to half throttle everything is ok, full throttle seems to be ok or even a little rich when reving in neutral. If i make a pull on the dyno I don`t reach the same revs as petrol (petrol ca 13000, NM/M ca 12000 U/min), and after closing the carb slide he won`t rev down fast enough, even keeps running with ignition cut down. Seems like clearly to lean, but its already the riches rod I´ve made (2/10mm to rich). Even the lower rpw would say to rich, or is 4 degrees retarded to petrol to less, an he ignites to early? From petrol to E85 I had to advance the Ignition roundabout 3-4°, so I thought 4° retarding could be a good starting point, cause I found no info about that. First result after 2 hours of testing 3,5hp less than on petrol, but without Stinger reduction, carb far away from perfect, ignition changes not tried until yet...
Would be great if someone knows something about the running without ingnition, ignition timing etc. Maybe there are mistakes in my before calculation, let me know!

[Hoebra]

I forgot:
Out of the fuel tube from the seperate chamber come constantly over 700ml/min, directly to the little reservoir under the neddle tube, so I won`t believe its running out of fuel, but I will take al look at this tomorrow, would be happy for any advice.
Ignition is an ignitech dc cdip2 2 Channles plugged to a crane coil PS92, Brisk LR08ZS, combustion ratio 13,8:1 like on petrol. I`m unshure about the last parameters in relation with NM/M.

[wobbly]

Hoebra - why are you only using 13.8:1 compression as was run on petrol.
Plain Methanol can be run at 18:1 as it has an effective octane of 130 petrol - seems to me you are leaving a huge power loss on the table with just that small change.
And when you have that high com number the ignition can remain as it was optimized on petrol.

[wobbly]

Diesel - here is what you want in a nutshell.
The transfers dont need any chamfer at all as the ring does not bulge outward into the relatively small chordal widths.
All they need is the edge at the bore broken with a cotton mop.
A proper " chamfer " at a transfer timing edge creates severe flow eddies off the corner , causing the transfer stream to loose coherency and thus directional control.

The big radius on the Aprilia Exhaust timing edge was instituted by Jan in response to his boss producing a new exhaust design that lost alot of top end.
Increasing the Blowdown efficiency by dramatically increasing the just opening ports Cd value , proved to eventually give more power everywhere.
Many years later I discovered that if you do an STA analysis on the ports , it would appear that the transfers were some 10% ahead of the Blowdown capability - just from the raw chordal data.
But the clever implementing of an increase in Cd of the Exhaust port ( that the sim code cannot recognize unless its written in as an option ) would in reality , bring the two most important sets of port data back into alignment.

[Hoebra]

I wanted ti start somewhere, so I left Combustion as it is. Methanol high compression ok, but there is also 50% Nitromethan, so I wasnt sure. You mean I should take more compression an ignition schould be increased? In my opinion ignition timing has to be retarded with higher compression an even without I already have self ignition?

[husaberg]

The traditionally accepted " rule" for the Exhaust port was 72% - this was used by Yamaha for decades in the RD based TZ range of customer race engines.
But these had very generous corner rads that , as Frits drawing shows , restricts the Blowdown area available.

I worked on a set of later model 4DP TZ cylinders ( 56 bore ) a while ago that had been " tuned " by a famous ex Roberts tech.
The Exhausts had ben widened to 75% with no change to the radi.
The owner wasnt overly thrilled when after the initial dyno runs , and two practice sessions , the new pistons timing edges were obviously belted to shit , and the rings were on the verge of trapping due to mental piston rock.

Angle area as a port metric has been also used for years , but imho , this metric when combined with rpm , that describes a ports effective open area and how long that area is available at a specific
engine speed ( STA ) , combines all of the data into a useful one for predicting power capability at a chosen rpm.

EDIT - added info. In a water cooled 125 race engine the power drop from running at 65*C exit temp Vs 45*C is 1.5 Hp in near 50.

Confused i thought 1000km or so for the pistons half that for the rings with the cranks about 2000km that prior the big bangs. the price of power i would guess the 125 ad 250s were changing stuff at a much quicker rate.
pistons every race cranks at 100

[wobbly]

Husa , the later model TZ engines would do the factory recommended 1500Km on a crank - and plenty were taken to 2000.
Pistons happy at 500Km , and fit a new ring as soon as blowby was seen.
Thing is at 500Km a piston would simply be worn , with double the original clearance - not ready to self destruct by falling into the port after 2 practice sessions.

[diesel pig]

Diesel - here is what you want in a nutshell.
The transfers dont need any chamfer at all as the ring does not bulge outward into the relatively small chordal widths.
All they need is the edge at the bore broken with a cotton mop.
A proper " chamfer " at a transfer timing edge creates severe flow eddies off the corner , causing the transfer stream to loose coherency and thus directional control.

The big radius on the Aprilia Exhaust timing edge was instituted by Jan in response to his boss producing a new exhaust design that lost alot of top end.
Increasing the Blowdown efficiency by dramatically increasing the just opening ports Cd value , proved to eventually give more power everywhere.
Many years later I discovered that if you do an STA analysis on the ports , it would appear that the transfers were some 10% ahead of the Blowdown capability - just from the raw chordal data.
But the clever implementing of an increase in Cd of the Exhaust port ( that the sim code cannot recognize unless its written in as an option ) would in reality , bring the two most important sets of port data back into alignment.

Great stuff! So with what you were saying about the Aprilia exhaust port history do I take it the exhaust edge radius only works to a power advantage with 10% undersized ports? Or does it work to a power advantage with properly sized exhaust ports?

[wobbly]

At the outer limits of power capability the Transfers and Exhaust Blowdown are fighting over the same real estate.
When I mentioned to Jan about the disparity between the STA numbers , his first reaction was that he should have tried lowering the Transfers.
He had said previously that they were never changed in timing , only area/direction.
Thus as always hindsight is all seeing, as his development concentrated on getting more Blowdown , firstly by enlarging the Aux , then increasing the main port Cd with a radius.

I have no clue if dropping the Transfers and keeping the original Exhaust port geometry would have worked , but if Aprilia R&D had an accurate sim package with inbuilt STA analysis , the disparity would have been obvious
immediately - maybe giving the insight needed into a previously unimagined development route.
Sadly the great leader told me in person that sims were an unnecessary waste of time , same thing I thought about him as it turned out.

[SwePatrick]

Next weekend is raceweekend, so we just wanted a little shakedown to see if everything worked.
No adjustments made for traction at all.

We reached 142km/h in roughly 100-110m (87mph in 330-345ft)
So i´m hoping for personal best upcoming weekend :)


https://youtu.be/SlrruBQlAcQ

[diesel pig]

At the outer limits of power capability the Transfers and Exhaust Blowdown are fighting over the same real estate.
When I mentioned to Jan about the disparity between the STA numbers , his first reaction was that he should have tried lowering the Transfers.
He had said previously that they were never changed in timing , only area/direction.
Thus as always hindsight is all seeing, as his development concentrated on getting more Blowdown , firstly by enlarging the Aux , then increasing the main port Cd with a radius.

I have no clue if dropping the Transfers and keeping the original Exhaust port geometry would have worked , but if Aprilia R&D had an accurate sim package with inbuilt STA analysis , the disparity would have been obvious
immediately - maybe giving the insight needed into a previously unimagined development route.
Sadly the great leader told me in person that sims were an unnecessary waste of time , same thing I thought about him as it turned out.

Is there a rough rule for the radius diameter vs exhaust port size? Or is it a matter of taking what was done to late model Aprilia cylinders and trying it out?
I must say things like this made the self important people who said two stroke development had reached a dead end in between the years 2000 and 2010 look like the pompous idiots they really are.

[Frits Overmars]

Is there a rough rule for the radius diameter vs exhaust port size? Or is it a matter of taking what was done to late model Aprilia cylinders and trying it out?Here you go Diesel.
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[diesel pig]

Here you go Diesel.
351428 351427

Perfect! With it in percentages it can be converted into any size. Top Man.

[OopsClunkThud]

Frits, I'm curious about the process of arriving at the radius of 5% of stroke.

Backing into the result...
In 2D CFD analysis the vena contracta is almost nonexistent when the port first opens and grows as the pressure ratio falls. A larger radius will have a more gradual port opening as the effective downward angle of the port swings from 75° to whatever the port roof is ~20-25° A Radius of 5% makes this transition in ~3.5° and seems optimized for a pressure ratio of ~1.6 or about the end of the blow down phase. This makes the radius large enough to prevent separation through all of blowdown, but would need the timing edge adjusted depending on where the radius is relative to the original timing edge.

If the timing edge were held constant with the radius effectively built up on the roof of the port, then the early blowdown phase will flow less because the radius blocks the path.
If the port roof were held constant with the radius being further cut upward then the timing is truly changed with blowdown starting earlier.
Using the wire bent at 45° to measure the timing edge seems to split the difference.

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[wobbly]

I would be interested to see the CFD analysis where , as in the Aprilia the radius I believe started at 202* duration , but the actual port roof angled at 25* was 196* - and measured
with the 0.7mm gauge the effective timing was at 198*.
Would be interesting to know what the original conventional roof timing was.
But what happens a bit further down the duct is just as important in my recent testing. For best power the 25* down angle turns into a convex radius , and the port floor is horizontal to the point
where the side ports enter the main duct, and then turns into a downward angled ski jump.
This minimizes the main duct area , exactly where the side ports are increasing the effective total.
When combined with the 75% exit area , this configuration gives a huge increase in power everywhere, simply changing the duct geometry.

[SwePatrick]

Honestly, i don´t think it´s needed to follow the blueprint 100% on that radiused top of exhaust.
As i know that when putting velocitystacks on a inlet (fourstroke), is like the first 90% of gains is just a chamfer on the straight pipe.

[Frits Overmars]

Frits, I'm curious about the process of arriving at the radius of 5% of stroke.Patrick, that 5% value was established empirically and given the number of possible combinations (the size of the radius and the offset of its center relative to the bore) we cannot exclude that the optimum might be a percent more or less.
I've always been playing with radii. It started when, at age 15, I radiused the piston top edge of my moped. Of course I didn't know what I was doing, but it worked.
I started fiddling with the exhaust port timing edge after reading about it in a book that I cherish. It is older than I am and it was written by professor Alfred Jante. He came up with 5%, also established empirically :rolleyes:.


I would be interested to see the CFD analysis where , as in the Aprilia the radius I believe started at 202* duration , but the actual port roof angled at 25* was 196* - and measured with the 0.7mm gauge the effective timing was at 198*. Would be interesting to know what the original conventional roof timing was.Both the 196° timing before radiusing the top edge and the 202° timing after radiusing were established with 'first light' visible at the ports top edge; no 45°-bent gage involved. I came up with the bent gage later, when trying to establish the effects of combined radii at both the port top edge and the piston top edge.


what happens a bit further down the duct is just as important in my recent testing. For best power the 25* down angle turns into a convex radius , and the port floor is horizontal to the point where the side ports enter the main duct, and then turns into a downward angled ski jump. This minimizes the main duct area , exactly where the side ports are increasing the effective total. When combined with the 75% exit area , this configuration gives a huge increase in power everywhere, simply changing the duct geometry.Wob, I am well aware of the excellent results that can be achieved with your exhaust duct geometry. However I think that minimizing the main duct area, exactly where the side ports are increasing the effective total, is not a goal in itself but a consequence of the fact that the cross flow area upstream of this minimum area is larger than it ought to be.
Raising the exhaust floor to about 10 crankshaft degrees below Transfer Opening would reduce the initial port area while leaving sufficient blowdown angle.area for even the most enthusiastic overrev. It would also reduce the risk of transfer short-circuiting, it would influence the horizontal course of the port floor, reducing or eliminating the ski hump, and it would raise the exit area value to over 75%.

[OopsClunkThud]

Honestly, i don´t think it´s needed to follow the blueprint 100% on that radiused top of exhaust.
As i know that when putting velocitystacks on a inlet (fourstroke), is like the first 90% of gains is just a chamfer on the straight pipe.

But if you were going for that 100% an ellipse with a semi-minor axis of 5% and a semi-major axis of ~10% would be even better than a radius.

[wobbly]

Frits I have signed an NDA with another KZ engine manufacturer who is desperate ( and has all the resource ) to try all of the things we have been discussing.
Initially all my work will be remote , in CAD ,up until the end of August where I am committed here to winning our KZ National Title again.
After that a flying visit to you and Marc is pretty much a done deal.
First order of the day is to do the cylinder/pipe analysis in EngMod , then carry on where Jan left off with the floor at 3mm ABDC.
Maybe I can retire when its at 9mm above.

[Frits Overmars]

Frits I have signed an NDA with another KZ engine manufacturer who is desperate ( and has all the resource ) to try all of the things we have been discussing.
Initially all my work will be remote , in CAD ,up until the end of August where I am committed here to winning our KZ National Title again.
After that a flying visit to you and Marc is pretty much a done deal.
First order of the day is to do the cylinder/pipe analysis in EngMod , then carry on where Jan left off with the floor at 3mm ABDC.
Maybe I can retire when its at 9mm above.I'm looking forward to it Wob :niceone:

[Peter1962]

Confused i thought 1000km or so for the pistons half that for the rings with the cranks about 2000km that prior the big bangs. the price of power i would guess the 125 ad 250s were changing stuff at a much quicker rate.
pistons every race cranks at 100


Frits I have signed an NDA with another KZ engine manufacturer who is desperate ( and has all the resource ) to try all of the things we have been discussing.
Initially all my work will be remote , in CAD ,up until the end of August where I am committed here to winning our KZ National Title again.
After that a flying visit to you and Marc is pretty much a done deal.
First order of the day is to do the cylinder/pipe analysis in EngMod , then carry on where Jan left off with the floor at 3mm ABDC.
Maybe I can retire when its at 9mm above.

That is great news !
Will this assignment also give you the opportunity to experiment with longer conrods (like aprilia had in the RSA, in sharp contrast to the short honda conrods ) or is it limited to the current 110 or 115mm that is used in KZ ?

I am gonna be cheering for you, winning the KZ Kiwi national title ! :wings:

[rgvbaz]

Last issue I saw they retested and got it to 95mph but it wouldn't pull 6th. They are getting a non-standard size sprocket machined to try and get the gearing right. The next issue should be out here soon!

Cheers

Dave


Well I'd been looking out for the latest issue to see how they are doing (mag takes months to get to NZ so we're out of date - yeah yeah;))

Ran to 106mph on the dyno at 12,000 which I think was well past their peak power. Net result so far; 87mph but unable to hold 6th gear. They had jetted down a step to try improve (where they got 87) & it nipped up. Apparently was just getting too hot between runs & not jetting fault.

I'd argue that aircooled bike is petrol cooled & it has to run that bigger than optimum jet.

Either way they are cleaning it up & rechecking on the dyno so we have to wait another month (unless we get a spoiler from overseas guys). They will try gear it down if they can't pull 6th this time. Frankly I think it was crazy they didn't have a range of gearing for a top speed attempt on a Tiddler.

I still predict 92mph. I am not trying to knock them, it is a good effort & the bike looks great for what it is, true to the original idea rather than a liner attempt (they drafted a kid to ride it). I just think a bigger carb & some more revs would have helped their cause somewhat.



[edit] July issue, just looked on site & Aug issue advertised so we're not that far behind, but no mention of it in blurb.

Not sure if anyone would still be interested but I happened upon an AR 50 a few years ago and then an Autisa 93cc kit tuned by BDK racing plus pipe.

I'm going to have a go at cracking 100 mph with it.

I'm documenting it on YouTube at the min. https://youtube.com/playlist?list=PLb2xMrRCECgmzT7fhoXnQKVCOpZJtxZCl

Cheers,

Dave

[F5 Dave]

That sounds like a ridiculous pointless endeavour.

Which is right up my alley so I'll bookmark that to watch later.

[rgvbaz]

That sounds like a ridiculous pointless endeavour.

Which is right up my alley so I'll bookmark that to watch later.

🙂🙂🙂 Cheers

It is intended for my lad one day when he gets to 16... He'll be able to get to the chippy quicker.

Dave

[husaberg]

������ Cheers

It is intended for my lad one day when he gets to 16... He'll be able to get to the chippy quicker.

Dave

Hi so whats the learner laws in the UK, is it still 50cc mopeds at 16 then ?

[rgvbaz]

Hi so whats the learner laws in the UK, is it still 50cc mopeds at 16 then ?

Yep - 50cc when you are 16... Limited too 30 mph. It's all mainly scooters nowadays for m what I've seen.

Dave

[F5 Dave]

Heres my take. Engineer yourself to success rather than tune with your hands tied.

First thing I'd do is find a decent rodkit so you can spin it out to 13,000 peak with some over rev. You will likely need to bore the crank. Could even find some stroke there if there is room. That will change the ballgame.
That pipe looks like peak is well short of 11,000.

An ignitech will make revs possible.

A turbo booster water pump can be driven from 12v. Just do the head for ease at first. Cut the fins off and simple jacket. Can add barrel later with an external u tube if desired. Bit on back for decent reedblock. Pwk28 should be sufficient.

Build a pipe, you'll be at 25+ hp without must sophistication in the ports, but that should hit 100mph.

Starve son for 3-4 weeks and set him loose on a windless day.

[rgvbaz]

Heres my take. Engineer yourself to success rather than tune with your hands tied.

First thing I'd do is find a decent rodkit so you can spin it out to 13,000 peak with some over rev. You will likely need to bore the crank. Could even find some stroke there if there is room. That will change the ballgame.
That pipe looks like peak is well short of 11,000.

An ignitech will make revs possible.

A turbo booster water pump can be driven from 12v. Just do the head for ease at first. Cut the fins off and simple jacket. Can add barrel later with an external u tube if desired. Bit on back for decent reedblock. Pwk28 should be sufficient.

Build a pipe, you'll be at 25+ hp without must sophistication in the ports, but that should hit 100mph.

Starve son for 3-4 weeks and set him loose on a windless day.

Top-tips Dave - thanks :)

I'd rather do it without resorting to water cooling; however...

I've always thought Dynojet HP is a little higher than reality. Testing my R9T on two different Dynojet dynos v my own showed 13% more power with the dynojets so the 21.3 (ish) they got is nearer 19 hp if my Dyno is anywhere near correct.

Got a lead on a ignitech so one will be going on - the std ignition goes full retard about 6k from memory so.no use at all.

Crank wise I think I had a scour of the Grampians catalogue and couldn't find a compatable kit but will keep looking.

Will be an interesting way to spend some money and time... :)

Cheers

Dave

[pete376403]

Would this ignition be any use? Use of Tuner Studio means you can create any ignition map you fancy. https://speeduino.com/forum/viewtopic.php?f=16&t=596

[wobbly]

Peter , the RSA had a case ratio down at 1.24 , due in part to the very long rod.
An RV loves a big case - reeds do not like anything below 1.3 as to run below that Helmholtz volume , the petals have to be too thin to work with it , and loose more power from lack of tip control than any gain seen
from the bigger case ratio.
Been there done that , as its real easy to simply add a reedblock spacer to gain case volume.
Adding a 5mm spacer took the engine under 1.3 and I spent a fortune in time and money trying to tune the reed frequency to suit.
Power rose as I went thinner ( or smaller backups ) , but it never came close in power to the original case and reed setup.
Just another free lunch in the bin.

[rgvbaz]

Would this ignition be any use? Use of Tuner Studio means you can create any ignition map you fancy. https://speeduino.com/forum/viewtopic.php?f=16&t=596

Possibly but it's getting it to the UK. There's a place fairly local that has a load of the single cylinder Ignitechs on the self so was going to give them a go.

I'm gonna have a go at converting the hole bike to 12v .

Cheers

Dave

[Frits Overmars]

An RV loves a big case...As we all know, RV is short for Reed Valve :msn-wink:.
Joking apart, we must live with the fact that Rotary and Reed both start with the same letter. Those who know and love Wobbly, won't be fooled, but newcomers might become confused. Suggestions, anybody?
My stay in Germany has made me allergic to abbreviations. Germans love them, but their abbrevs make Google Translate burst into tears.
Can you imagine what KW stands for? Yes, that's what I thought too, until I found out that the Krauts also use it as an abbreviation for Kurbelwelle (=crankshaft).
This can lead to hilarious technical discussions where one half gets the impression that the other half has been testing too much ethanol.
Italians love abbrevs as well. I have enough of the lingo to be able to guess right most of the times (and so will Wobbly by now, I suppose) but think of all those forum visitors who are relying on Google Translate. That is why I prefer to write my texts in full instead of full of abbreviations.

[pete376403]

As we all know, RV is short for Reed Valve :msn-wink:.
Joking apart, we must live with the fact that Rotary and Reed both start with the same letter. Those who know and love Wobbly, won't be fooled, but newcomers might become confused. Suggestions, anybody?
My stay in Germany has made me allergic to abbreviations. Germans love them, but their abbrevs make Google Translate burst into tears.
Can you imagine what KW stands for? Yes, that's what I thought too, until I found out that the Krauts also use it as an abbreviation for Kurbelwelle (=crankshaft).
This can lead to hilarious technical discussions where one half gets the impression that the other half has been testing too much ethanol.
Italians love abbrevs as well. I have enough of the lingo to be able to guess right most of the times (and so will Wobbly by now, I suppose) but think of all those forum visitors who are relying on Google Translate. That is why I prefer to write my texts in full instead of full of abbreviations.


DV - disk valve?

[philou]

Google translate, translated "rv" by "camping car" in French

[Muhr]

What about rotary valve :)?


This looks like desperatinon to me. Should have come further nowadays

[wobbly]

Sorry Frits , its just habit me saying RV for a Rotary Valve , and simply Reed for the other. Disc Valve seems good but then DV wont translate well either I would imagine.
Looking at that dyno graph with temps in the mid 20*C gets up my nose as I am struggling with breaking double digits at the moment.
I have been meaning to ask on here for a while now , are there any newer , better correction factor systems that have been published.
The one I have been using forever is SAE J1349 and with an ambient temp difference of say 5*C ( eg 12 * to 17 * ) the correction is nowhere near close enough.
Anyone got some help here , as even trying the DIN , JIS and ISO corrections in the software im still way off.

[Grumph]

You may have to work out your own. Based on experience.

May i suggest WTFF for a name - Wob's temperature fudge factor.

[Frits Overmars]

are there any newer , better correction factor systems that have been published. The one I have been using forever is SAE J1349 and with an ambient temp difference of say 5*C ( eg 12 * to 17 * ) the correction is nowhere near close enough. Anyone got some help here , as even trying the DIN , JIS and ISO corrections in the software im still way off.I too have found that neither the SAE, DIN, JIS nor ISO correction factor systems are any good for high-performance two-strokes, so I developed my own system ages ago.

[porttiming124]

I too have found that neither the SAE, DIN, JIS nor ISO correction factor systems are any good for high-performance two-strokes, so I developed my own system ages ago. Here you go Wob.

Hello Frits.
Do you want to share this corection system?

[Frits Overmars]

Hello Frits.Do you want to share this corection system?Yes, I was going to. I just needed some time to try and make it readable.
351453

[Muhr]

We have thought and tested quite a lot regarding this. Do not really know what you mean by "double digits" but an HP curve within a tenth or two you want between the days, which I think you can do. On the other hand, we experience that there is a little difference between the seasons, which I suspect has to do with oxygenation in the air, which we do not measure and correct for in any correction factor that I know of. Then it is as it is with results between different dynos

Exactly as you mentioned earlier, good control of water temp and exhaust temp is a key regardless of correction

Excited to test Frits correction factor, hope you solved this.

[porttiming124]

Yes, I was going to. I just needed some time to try and make it readable.


I will try it, A big thank you Frits.

[wobbly]

Thanks Frits , I will have a go with this asap.
Double digits means our ambient air temp is often below 10*C at the moment.
But the power variation is way too big to get meaningful results when I go from say 10*C to 15 *C even if the humidity and mBar are the same.

[Muhr]

Ok understand!
Suppose you tried a web-based calculator (https://robrobinette.com/Dyno_Correction_Calculator.htm) to see that you have no problem with the software.

[Peter1962]

Peter , the RSA had a case ratio down at 1.24 , due in part to the very long rod.
An RV loves a big case - reeds do not like anything below 1.3 as to run below that Helmholtz volume , the petals have to be too thin to work with it , and loose more power from lack of tip control than any gain seen
from the bigger case ratio.
Been there done that , as its real easy to simply add a reedblock spacer to gain case volume.
Adding a 5mm spacer took the engine under 1.3 and I spent a fortune in time and money trying to tune the reed frequency to suit.
Power rose as I went thinner ( or smaller backups ) , but it never came close in power to the original case and reed setup.
Just another free lunch in the bin.

Thank you for a very clear answer. I keep making the wrong assumption that the advantage for a long rod is in the mechanical benefit of having less tilting of the piston in the cilinder when in fact the case ratio is the more important factor.

[wobbly]

You are correct though , the long rod absolutely has inherently less bore thrust friction.
But the effect on a two stroke is muddied somewhat by the dwell time differences at TDC/BDC as well.
This I suspect is another one of those Catch 22 situations like crank inertia's effect on acceleration Vs in cycle rotational speed variations effect on transfer STA.

Muhr , that calculator uses the J1349 correction , that I was complaining about as not having anything like the compensation needed. And all the other corrections in the SportsDevices code have quite similar final results.

[husaberg]

Forgive my ignorance but wouldn't the best correction factor just be a separate reference engine.
Much like the octane mule engine of old. I know it would be to be run often but it should give a pretty repeatable base reference?

Even with central heating and thermostats our house inside temp is variable here by 4 deg and about 12% humidity.
i would hate to think what the shed varies by.

[Muhr]

OK I understand.
The idea from my side with the page was to compare results to rule out that there is a local problem.
We use DIN. I think it is relatively good correction between days.
Here is an old picture I had in the phone on ref between 2 days with about 5 degrees difference.

[wobbly]

Trouble is we are talking a temp difference of 10*C to 30 *C , a baro of 990 to 1020 mBar and humidity from 45 to 85% in any combination.
I have various jetting programs that also give engine power correction and they are all close to the corrections given in the dyno software , but I see a difference of near 2 Hp in 50 with an identical
engine setup simply going from 25* C then a couple of days later its 15*C with the baro and humidity pretty much the same.
Thus I can only really do same day comparative tests using a baseline im trying to better - and that wastes a huge amount of time repeating the same setup every day , then having to make the change to the pipe or cylinder.
And more of annoyance is tests I did a month ago , bear no resemblance to the current one , unless the RAD , that drives the dyno compensation tables is essentially the same - even with identical egt targets.

[philou]

https://zupimages.net/up/22/28/q2h2.jpg

https://scooterlab.uk/quattrini-adds-30-extra-power-to-his-2-stroke-kits-tuning/

[F5 Dave]

. . . And that's the desperate sort of stuff you might try to get around the fundamental constraints of through hole studs in a scooter engine I guess.

Outer ports are much longer, but ring still sees a square port with a plated edge just begging to be nibbled away.

[wobbly]

The reason there might be no "real " flow till the Aux open is because the mains roof timing is way too low, ie they are virtually the same .
Thus a large amount of Hp bandwidth is lost , as stagger , where the main port is higher - gives rise to a much more intense amplitude wave front exiting into the duct, increasing both leftward and rightward wave action.

As it stands , due to the huge disparity in Blowdown path lengths the initial wave front will be reduced in amplitude and also severely smeared out in time.
In a conventional 3 port, if all are opened concurrently , big power losses occur on both sides of peak.
This shows the inherent limitations of using flowbench data to drive development strategy.
Edit - this is why the Aux are square , as the flowbench ( and the designer ) knows nothing about upward short circuiting from the A port.

[Flettner]

A useful thing just turned up. Heat treating at home.

[Niels Abildgaard]

UK postal service dream of serving remote locations with drones that can move 100 kg 1000km.
Their first versions are driven by Briggs and Stratton Vanguard twin 38 cui lawn mover engines and we all can think of better ways.
UK Flying Post Angels will need plus 200 engines per year if these can be low mass,reliable and frugal.

[URL="https://www.dieselprogress.com/news/Vanguard-powered-UAVs-bring-aid-from-above/8013169.article"]

An inverted single cylinder two stroke direct drive with exhaust valves as a Honda Cub (More than 100 millions made)
will be better for making 30 horsepower at 60 rps.
76 mm bore and stroke 112mm.

351480

More words and maybe a working link can be seen here

https://www.homebuiltairplanes.com/forums/threads/fastest-planes-on-the-least-amount-of-hp.36052/page-5


https://drive.google.com/drive/folders/1YNYWcnGSqsfYqu_EV1XM_g0HQ9pOxbmv

https://windracers.org/

[Niels Abildgaard]

A know it all ESE user can do valuable deeds for humanity etc.
Tuned exhaust pipes as we know them does a good job of converting blowdown kinetic energy to suck and blow back.
The blowback is not needed in this aero aplication as a MEP of 7.5 bar will do and exhaust closing timing is done by camshaft.
How long aproximately shall pipe be?

351481

My beloved MZ301 had a pipe of ca 1.2m length and came on at cirka 50 rps (3000rpm)

[andreas]

Seems like you are talking about a two stroke uniflow, to my knowledge the honda cub engine is not one of those. How long a diffuser only, pipe shold be? Of course all the usual input: rpm, ex open etc is required.

[Niels Abildgaard]

Seems like you are talking about a two stroke uniflow, to my knowledge the honda cub engine is not one of those. How long a diffuser only, pipe shold be? Of course all the usual input: rpm, ex open etc is required.

Different wording for another fellow scandinavian

"with a cylinder head like a Honda Cub with two exhaust valves "

I really have not the faintest idea of best timing and asume that a clever guy with a good programe can optimize timing and pipe simultaineously

Input parameters are ca 76 mm bore,112mm stroke, 30 horsepower and 60 rps.

[andreas]

Ok, I understand now. Someone probably could do that, just prepare for a less than significant increase in power, because the poppet valves don't give nearly as high wave amplitude as an ex port, and there is only the expansion wave doing work.

[Niels Abildgaard]

Ok, I understand now. Someone probably could do that, just prepare for a less than significant increase in power, because the poppet valves don't give nearly as high wave amplitude as an ex port, and there is only the expansion wave doing work.

The holy and perfect Aprilia was once run without any pipe and inlet resonater etc by Jan Thiel and it gave an Mep of 6 bar.
We need 7.5 and has much better trapping due to longstroke uniflow.
Pipe are not asked to make miracles

[andreas]

I like the altruistic agenda, and it doesn't seem unrealistic for it to work.

[Flettner]

Haha, popet valves are for toilets.

[Niels Abildgaard]

I like the altruistic agenda, and it doesn't seem unrealistic for it to work.

Two counterrotating ,synchronized single cylinder engines give cargo and airframe an easy ride as torque reactions cancel.
When one engine quits it is not a disaster,but slower mail.

[ceci]

UK postal service dream of serving remote locations with drones that can move 100 kg 1000km.





They are already working, and more than 100 Kg, I am not sure but I think I have seen some, since their fuselage is different from that of light aircraft (the double rudder is not usually common in common light aircraft)

https://dronedj.com/2021/07/14/franco-spanish-raid-busts-criminals-using-souped-up-drone-to-transport-drugs/

https://english.elpais.com/spain/2021-07-15/spanish-police-seize-large-drone-used-to-carry-drugs-from-morocco.htmlhttps://dronedj.com/wp-content/uploads/sites/2/2021/07/DRON.jpg?w=900&h=600&crop=1

[peewee]

guys let me ask something about the divider between main exh and secondary on a cylinder with iron liner. 1mm wide should be fine i think but what about .75mm. the liner is thick so it should be strong enough just to keep the ring in the groove. it might wear down faster but i dont care

[wobbly]

Depends how close to 70% the main port is.
At this width the ring absolutely does bulge out into the port , and the bridges are heavily point loaded when pushing the ring back into the groove.
Having an oil hole drilled thru the piston directly over the bridge will help , just as it does for T port bridge wear issues.

[peewee]

its slightly under 70% if i recall. i may put a bit of arc on the roof to be safe. when i was punching the new windows into the liner i fucked up and grinded the secondaries closer to the main than i wanted. to some what match the liner to the main its going to leave a thin divider of 1mm or so

[Condyn]

I had issues with a 1-2mm wide iron bridge between aux and main before. This was an application where I had to make the aux tight to the main because of stud bore constraints. It overheated the bridge. I did not have oil holes drilled.

[peewee]

i always put oil holes in the piston for any type of exh bridge. also i grind a resorvoir into the liner below the bridge so it fills with oil at tdc then the piston walls carry the oil over the bridge on the next cycle. 1mm isnt much surface area and more than anything i figure they will wear down faster and perhaps maybe crack. only one way to find out :cool:

[jonny quest]

Holes in piston, channels.... for oil may help at idle.

Full song, full heat, they are doing anything

[wobbly]

Yes , in the Aprilia and the TM the piston skirt pushes on tongues each side below the boost port.
Holes got rid of wear marks in both engines.
And of course any RS125 Honda , RM/RGV125/250 with a T port would tear up the skirt without oil holes in no time.

[ceci]

I do well to show it or not, I know that I do not enjoy much sympathy and surely with things like this I will have less.


how a bout two fingers that slide into the reed cage and hold the petals open, obviously won't work on vforce reeds and more petals = more fingers.
could simply have the fingers attached by cable to the powervalve, no extra servo, 24/7 during the powerband.


That's the general idea, TerraRoot; the 24/7-valve and the exhaust powervalve can be synchronized.
But you do not need a fancy reed cage. As long as the engine is running below the powerband, it is not making power anyway, so the reed does not have to be sophisticated; a simple single reed petal will suffice. Remember, it is there only to start the engine. And instead of a finger to hold the reed open, you can mount the reed on a shaft; that makes swinging it out of the way much easier.
Here is that original picture once more for those of you who haven't seen it yet: over-engineered like I said. One shaft with one petal (and of course no gears) will suffice.

https://worldwide.espacenet.com/patent/search/family/015947511/publication/JPS6065228A?q=pn%3DJPS6065228A

https://worldwide.espacenet.com/patent/drawing?channel=espacenet_channel-f281c010-9002-4c78-be14-946c2ad18c33

[OopsClunkThud]

The reason there might be no "real " flow till the Aux open is because the mains roof timing is way too low, ie they are virtually the same .
Thus a large amount of Hp bandwidth is lost , as stagger , where the main port is higher - gives rise to a much more intense amplitude wave front exiting into the duct, increasing both leftward and rightward wave action.

As it stands , due to the huge disparity in Blowdown path lengths the initial wave front will be reduced in amplitude and also severely smeared out in time.
In a conventional 3 port, if all are opened concurrently , big power losses occur on both sides of peak.
This shows the inherent limitations of using flowbench data to drive development strategy.
Edit - this is why the Aux are square , as the flowbench ( and the designer ) knows nothing about upward short circuiting from the A port.

Has opening the aux ports before the main been tried as a way of aligning the wave fronts given their different path lengths?

Opening the aux after the main would seem to "smear" the wave front even more, but maybe it puts it far enough behind the wave front that it doesn't disrupt things. With the extra path length and ~5° of stagger, back of the envelope looks like the aux could be as much as 1.5 bores behind.

[wobbly]

Yes Kawasaki built a 125MX with the Aux higher and their own power valve - was a dismal failure and was quickly replaced.
I did some consult work for a Belgian company building RS125 Honda cylinders , I got them to try reversing the timing angle on the T port.
That is the outer edges at 100% of bore were the highest.
In the end after lots of tests it proved to be no better , but lost quite a bit off the pipe.
The A kit setup was a dead straight timing edge @ 200* duration , that made easily the best power with the short A kit pipe/ignition/carbs etc.

PS - the staggered Aux dont have anything like the P Delta across the port into the duct , and work more as a bleed down of remnant Blowdown pressure rather than generating a high amplitude wave front, like the min does when opening by itself.

[JanBros]

Yes Kawasaki built a 125MX with the Aux higher and their own power valve - was a dismal failure and was quickly replaced.


not questionning your knowledge Wobbly, but the KR1S also has higher aux' and it's performance is at least on par with the other 250's. in fact it's still the fastest 250 production bike ever.
or is the BMEP of these 250's road bike not enough to make a difference ?

[Frits Overmars]

not questionning your knowledge Wobbly, but the KR1S also has higher aux' and it's performance is at least on par with the other 250's. in fact it's still the fastest 250 production bike ever. or is the BMEP of these 250's road bike not enough to make a difference ?I encountered the higher-than-main auxiliary exhaust ports of the Kawa KR1S when a friend rode one in a Dutch Standard class of 400cc four-cylinder foul-strokes against 250cc two-cylinder two-strokes (life ain't fair).
The rulebook allowed no more than 1 mm deviation from all standard port dimensions and all I did on the cylinders was raise the main exhaust ports 1 mm and fit 1 mm base gaskets that were later substituted by fitting Yamaha TD2 pistons with 1 mm less compression height. I used cylinder head inserts that restored the combustion volumes and fitted homemade pipes. We were not allowed to do anything about the 28mm carbs; all I did on the intake side was shorten the inlet rubbers about 5 mm. With 73 rear wheel-HP it was the fastest bike in its class, making fools of those 400cc foul-strokes.
The point I am trying to make: the little Kawa was a fine bike alright, but I doubt its original higher-than-main auxiliary exhaust ports were of any benefit for power.
My guess: Kawasaki may have tried to avoid power valves in the main exhaust ports because of patent infringement reasons, so they put valves in the auxiliary ducts, and then it would make sense to make those auxiliaries higher than the main port.

[husaberg]

I encountered the higher-than-main auxiliary exhaust ports of the Kawa KR1S when a friend rode one in a Dutch Standard class of 400cc four-cylinder foul-strokes against 250cc two-cylinder two-strokes (life ain't fair).
The rulebook allowed no more than 1 mm deviation from all standard port dimensions and all I did on the cylinders was raise the main exhaust ports 1 mm and fit 1 mm base gaskets that were later substituted by fitting Yamaha TD2 pistons with 1 mm less compression height. I used cylinder head inserts that restored the combustion volumes and fitted homemade pipes. We were not allowed to do anything about the 28mm carbs; all I did on the intake side was shorten the inlet rubbers about 5 mm. With 73 rear wheel-HP it was the fastest bike in its class, making fools of those 400cc foul-strokes.
The point I am trying to make: the little Kawa was a fine bike alright, but I doubt its original higher-than-main auxiliary exhaust ports were of any benefit for power.
My guess: Kawasaki may have tried to avoid power valves in the main exhaust ports because of patent infringement reasons, so they put valves in the auxiliary ducts, and then it would make sense so make those auxiliaries higher than the main port.
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=261773&d=1334054656
https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130300124#post1130300124
https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner?p=1130300150#post1130300150

Golly frits that was 10 years ago when we had almost the same conversation.

[Frits Overmars]

Golly frits that was 10 years ago when we had almost the same conversation.Time flies, doesn't it? But when re-reading that old post of mine, I noticed an error.
Fitting Yamaha TZ250G pistons (lighter, stronger, cheaper(!) and with 1 instead of 2 rings and 1 mm shorter from pin centre to top edge), raising the centre exhaust to the same height as the auxiliaries and milling the cylinder head made it faster than all the foulstrokes.Ø54mm Yamaha TZ250G pistons in those Ø56mm Kawa KR1S cylinders wouldn't have worked very well. I used the older Ø56mm Yamaha TD2 pistons in the Kawa.

[JanBros]

I used cylinder head inserts that restored the combustion volumes and fitted homemade pipes. We were not allowed to do anything about the 28mm carbs; all I did on the intake side was shorten the inlet rubbers about 5 mm. With 73 rear wheel-HP it was the fastest bike in its class, making fools of those 400cc foul-strokes.


anymore info on the cc's and squish area of the head ? and stretching your memory/kindness : dimensions of the pipe ?
and with that power, what about the cracking cylinders arround the stud holes ? first the rear crack, and when you strengthen the back of the cylinders, the front crack :weep: one off the reasons most KR owners don't seek outright power but wider powerband and torque.

don't know if you've ever heard of the RGV-challenge ? http://www.rgv250.co.uk/forums/topic/32842-rgv-challenge/?_fromLogin=1

for those without a login :

I must admit to having a chuckle about all the tuning threads on this forum.

With so many people trying to tune the RGV isn't it time you lot came up with a half decent tune that was proven and available to all. There must be enough collective experience on this site to come up with a decent motor.
I have seen lots of bling bits for the RGV - heads, valves, pipes, ignition etc but I have yet to see a decent 250cc motor. Note the emphasis on 250cc.
VJ22 barrel is half decent, transfer port area is good, only weak point is the exhaust port which I think is too high (and people insist on making it higher) and doesn't have enough time area. Crankcases and flow through them needs work but this seems to be an area that is never touched (got the best part of 6hp on the KR from case work).
So I am going to set the forum a challenge
Build a VJ22 motor that out grunts on Krazy Katt's dyno my KR (got to think through how this will be decided)
Then because dyno runs are one thing and the track is another put the engine in either an Aprilia or an RGV chassis and beat my KR's single lap time and average race time (at least 8 laps) around Cadwell. You can choose your chassis and your rider. This test is the ultimate you need a good engine for a fast lap time and to keep it up for 8 laps it must be reliable.
Details of the engine spec (tune) must be made available on this forum so others can build a decent RGV engine.
I will put up as a prize ?500 as an incentive for you lot to do it - prize to the first entry to succeed
I will have a chat with James (Krazy Katt) and Jim (Arch) about the rules (they don't know this yet) and will post the final set up here.
If you manage to do it I reckon you should pay me - but first lets see if you can do it http://www.rgv250.co.uk/forums/uploads/emoticons/default_smile.png (http://www.rgv250.co.uk/forums/uploads/emoticons/default_smile.png)





challenge came from Marc Jordan, the guy that se the Bonneville record on the KR. no one succeeded , and if memory serves me right, not even one came close or had a go on the specified dyno.

[Frits Overmars]

anymore info on the cc's and squish area of the head ? and stretching your memory/kindness : dimensions of the pipe ? and with that power, what about the cracking cylinders arround the stud holes ? first the rear crack, and when you strengthen the back of the cylinders, the front crack :weep: one off the reasons most KR owners don't seek outright power but wider powerband and torque.It wouldn't surprise me if Husaberg is going to point out that I answered these questions ten years ago as well, but for now I will stretch my memory.
My Kawa KR1S combustion chamber shape was the same as that of the Aprilia RSA from 15 years later, with 50% squish area and 1% squish clearance, but with a lower compression ratio: 12:1 if I remember correctly. I can't help you with the exhaust pipe dimensions; my memory is not that stretchable.

I never cracked a cylinder stud ear, but I've seen it happen with Honda, Kawasaki and KTM cylinders. But I've never heard of KR owners seeking wider powerband and torque instead of outright power in order to avoid the cracking and I cannot imagine that it would make any difference at all. From what I've seen, using huge stacks of paper base gaskets seems to be the #1 cause for the cracking.

[F5 Dave]

I remember reading that they could be quite variable in barrel height. Measure everything.

[wobbly]

Shit yes, I should have remembered the KR1S as back in the day I had a production line going modifying them - I would have done at least 20.
This used an alloy base plate cut out by a CNC wood routing machine , as there were no laser or water jets here back then - as you are right Frits a bunch of paper would crack the ears off.
It was the fastest bike in proddy racing , but our tech rules were very lax back then and Honda generally was the way to to as the F2 kit parts went straight on and no one knew how to
discern ( or didnt care ) the changes.

[peewee]

It wouldn't surprise me if Husaberg is going to point out that I answered these questions ten years ago as well, but for now I will stretch my memory.
My Kawa KR1S combustion chamber shape was the same as that of the Aprilia RSA from 15 years later, with 50% squish area and 1% squish clearance, but with a lower compression ratio: 12:1 if I remember correctly. I can't help you with the exhaust pipe dimensions; my memory is not that stretchable.

I never cracked a cylinder stud ear, but I've seen it happen with Honda, Kawasaki and KTM cylinders. But I've never heard of KR owners seeking wider powerband and torque instead of outright power in order to avoid the cracking and I cannot imagine that it would make any difference at all. From what I've seen, using huge stacks of paper base gaskets seems to be the #1 cause for the cracking.


with thick gaskets do the nuts pull down the corners and the middle is bowed up ? i remember seeing a cyl with a extra bolt half way between the corners ,probly for that reason im sure. brc500 i believe it was

[JanBros]

It wouldn't surprise me if Husaberg is going to point out that I answered these questions ten years ago as well, but for now I will stretch my memory.
My Kawa KR1S combustion chamber shape was the same as that of the Aprilia RSA from 15 years later, with 50% squish area and 1% squish clearance, but with a lower compression ratio: 12:1 if I remember correctly. I can't help you with the exhaust pipe dimensions; my memory is not that stretchable.

I never cracked a cylinder stud ear, but I've seen it happen with Honda, Kawasaki and KTM cylinders. But I've never heard of KR owners seeking wider powerband and torque instead of outright power in order to avoid the cracking and I cannot imagine that it would make any difference at all. From what I've seen, using huge stacks of paper base gaskets seems to be the #1 cause for the cracking.

tnx again. I have saved a quote from you explaining what you did with the cylinders on that specific bike from your friend, but there was nothing in it about the cylinder head.
the cracked ears are "common" on tuned KR's, happenned to mine to and I never use base multiple gaskett's (or thick ones, or lose base plates) to raise the barrel

[pete376403]

tnx again. I have saved a quote from you explaining what you did with the cylinders on that specific bike from your friend, but there was nothing in it about the cylinder head.
the cracked ears are "common" on tuned KR's, happenned to mine to and I never use base multiple gaskett's (or thick ones, or lose base plates) to raise the barrel
Did you ever machine the top of the cases where the barrel sits to ensure it was flat and square? I recall reading that earlier Kawasaki (early 70s F9) cases were not machined as pairs and could be mismatched at the barrel join

[husaberg]

Did you ever machine the top of the cases where the barrel sits to ensure it was flat and square? I recall reading that earlier Kawasaki (early 70s F9) cases were not machined as pairs and could be mismatched at the barrel join

I have mentioned this before but i believe the old 1970's Kawsaki multis were not line bored which i why people say not to run lab seals in them unmodified
but Legend is Yamaha and Suzuki miultis were.
no idea if it true or not but i have seen tales of lab seals being added to Kawasaki threes and them only lasting a couple of hundred Km's.
Honda i think went through a stage in the early 80's were then never line bored cams and caps etc.

[JanBros]

Did you ever machine the top of the cases where the barrel sits to ensure it was flat and square? I recall reading that earlier Kawasaki (early 70s F9) cases were not machined as pairs and could be mismatched at the barrel join

no and there are no problem's whatsoever with the KR1-cases.
what you do have to check is the height of the barrels, there can be a fifference between them. and always first tighten the headbolts before tightening the barrels.

and KR1's do not have a single seal between cylinders, each crankcase has their propriat seals, so no need (or probably space) for lab seals. in between both crankcases is the gear for the balance shaft.

[Frits Overmars]

I have saved a quote from you explaining what you did with the cylinders on that specific bike from your friend, but there was nothing in it about the cylinder head.With the 1 mm base gaskets, and later with the 1 mm shorter pistons, I had to restore the combustion volume somehow and I did not want to shave the cylinder top decks.
Raising an exhaust port in order to adapt a standard cylinder is something you can do in a paddock if need be; shaving the cylinder top decks is not. So I modified the 2-in-1 cylinder head and made inserts.

Here is another modification that I did not mention before. If you remove the reed valve bodies an look into the cases, you will see that the cylinder sleeves are rather obstructive. But you can grind a lot of sleeve material away without affecting the piston support area.

A bike that leaves its rivals standing draws attention and rumors about illegal works cylinders arose. The KR1S cylinders have resonator boxes coupled to the auxiliary exhaust ducts but I suspected they would bring unwanted heat into the cylinders, so I blocked them. This enabled me to omit the boxes, and without those I could fit the right hand cylinder to the left and vice versa: My engine without the lateral boxes that are so prominent on the standard engine below, had a proper works look :msn-wink:.
351545

[JanBros]

mostly people mount extra spacers to the KIPS boxes, never tried it, but will try blanking them off.

yep, a lot off material can be removed in front of the reads to improve flow

original :
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=351546&d=1660084197&thumb=1&stc=1https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=351547&d=1660084197&thumb=1&stc=1

what I made of it :
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=351548&d=1660084197&thumb=1&stc=1

I also cleared an original head and installed inserts, but later I developped a complete new head and had it CNC'd

https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=351550&d=1660084500&thumb=1&stc=1https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=351551&d=1660084674&thumb=1&stc=1

sold about 18 of those heads

[JanBros]

and made extra sealing for the KIPS valves, placed in the barrels
https://www.kiwibiker.co.nz/forums/asset.php?fid=311095&uid=33058&d=1660084500

also use 4 kit-valves (one side open), needed to reverse rotation of KIPS-motor and make new links so they all turn correctly
https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=351552&d=1660085086&thumb=1&stc=1

[yatasaki]

Made double KIPS boxes ...nothing happened, my guess is that KIPS duct is too small.

[Frits Overmars]

yep, a lot off material can be removed in front of the reads to improve flowYes it can, Jan. But what I was trying to point out, is that the part of the cylinder sleeve that enters the crankcase, obstructs the inlet flow, and it can easily be ground away, like along the yellow lines in the picture below. And no, that is not a KR1S cylinder; you wish! I just chose this picture because it was suitable to show what I mean.
351553

[JanBros]

the next revision of one of my engines is going to be much more work than expected :yes:

[F5 Dave]

Let's talk about running it on fermented coconut oil. The grinding stage will absorb most of your time.
In the interests of science of course.

[husaberg]

Yes it can, Jan. But what I was trying to point out, is that the part of the cylinder sleeve that enters the crankcase, obstructs the inlet flow, and it can easily be ground away, like along the yellow lines in the picture below. And no, that is not a KR1S cylinder; you wish! I just chose this picture because it was suitable to show what I mean.
351553

That leads to a question when Jan did the work with the reed valve did he mod that part of the original cylinder i understand he made a few changes but i dont recall him or you ever saying what changes wre made.

https://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=261462&d=1333621581


A technical explanation? Nah, too much to do today. But since you were kind enough to post that picture of your sex six sisters, I will show some curves of my own.
When Jan Thiel went to Derbi to design the bike we now know as the Aprilia RSA125, he encountered the 125 cc reed valve Derbi ridden by Lorenzo the previous season. Jan played around with the reed valver as well, because he wanted to find out the differences between reed valve and disk valve power. He managed to extract 2 HP more from the reed valver than anyone else had ever done before (never mind the fairy tales of reed valve 125s producing over 50 HP; those Horses must have been Shetland ponies, probably measured at the piston ring).
My graph shows the power curve for the Aprilia RSA, the Aprilia RSW and that best-ever reed valve Derbi. It's not quite in the same league as the rotaries, hmm?

EDIT: Shame on me; I discovered that I posted a wrong graph (and I do not have the correct one at hand here in Holland). Power curve DERBILOR shows the reed valve Derbi as Lorenzo rode it. After Jan finished playing with it, it had 49 HP. Still, the best-ever disk valver produced 10 % more power than the best-ever reed valver.

[Frits Overmars]

That leads to a question when Jan did the work with the reed valve did he mod that part of the original cylinder i understand he made a few changes but i dont recall him or you ever saying what changes were made.I must have a stack of Derbi drawings somewhere back in Holland but don't recall every detail and maybe some mods were never captured; Jan had a knack of modifying and testing first, and having the mods drawn afterwards. But it's safe to assume that Jan tested every mod you can think of, and then some.
Besides, you can ask Jan directly; he is looking in from time to time.

[husaberg]

I must have a stack of Derbi drawings somewhere back in Holland but don't recall every detail and maybe some mods were never captured; Jan had a knack of modifying and testing first, and having the mods drawn afterwards. But it's safe to assume that Jan tested every mod you can think of, and then some.
Besides, you can ask Jan directly; he is looking in from time to time.

Jan Thiel the name ring a bell....


To meet the RSA power was used 5 days per week by 6 people and with it the aid of the drawing room, and electronic engineers. And that over about 12 years is not that simple ! We started in 1995 with 46.5 hp, and ended in 2007 with 54hp, so 0.6 to 0.7 HP per year on average. Actually seems very little , but it was a lot of work ! We made about 300-400 cylinders per year. So to get that far, there are at least 3600 cylinders made. But maybe 4800 !, I did not count them .... Of course, a lot of cylinders were equal to each other ! But we surely tested 30 different types of flushing channels, and also exhaust conduit 20 different types. Estimated that another 100 different cylinder heads and of course lots of exhaust pipes!

[peewee]

hey wobbly how many things do you and frits disagree on ? besides if the A or B transfer should open first :laugh:

[wobbly]

Nothing that i can remember , except a long time ago about the values of peak cylinder pressure - but I am also sure Frits agrees that reverse stagger scavenging favors top end and gives room for bigger Aux ( along with less A port short circuiting ) , plus the higher B,C are wider thus naturally gives more transfer STA to match high Blowdown.
Normal stagger favors front side power , and is ideal if there is no PV - and or for naturally more mid for MX etc..

[peewee]

maybe it wasnt which port should open first but if the one to open first flows first. im sure frits will set me straight :clap:

[wobbly]

Thats easy to logic thru. When you see the pressure traces in EngMod ( or even last century in Dynamation ) , at TPO there is more residual Blowdown pressure above the port , than in the case , below it.
Thus this positive P delta, causing reverse flow back into the duct , affects the first opening port the most , this gave rise to the " first to open , last to flow " premise.
It is in fact how port stagger scavenging regimes actually work at all.
Also explains why power drops with excess Blowdown STA numbers.

[husaberg]

Nothing that i can remember ,.

Toroidal vs Bathtub?