ESE's works engine tuner

[dtenney]

Does anyone have the measurement from the disc to the piston face for the Aprilia RSA?

Thanks

[Flettner]

First off, I make no claims, its an experiment and a bit of fun at that.
Question about the stud pattern, as I make my own stuff I can have whatever I want. Studs go where I decide.
Im sticking to the two pipes for now to see how the powervalve might effect things. If I can't get a resonable result / answer, Im looking at a two into one true volume split header into a single pipe. See what that brings.
With my CNC I should be able to make a press tool to make an accurate volume joiner.
Pipes are loosely based on 2 x KX65.

[Flettner]

We could argue about this for ages.
Just what the thread needs. Stinger has been covered here but it makes sense to me to have the same combined area as a single pipe (so 1/2 by area) and then experiment.

The belly section should be derived using the same angles but starting with a much smaller header pipe. But my brain is melting here and now I've entered a highly suggestable state so I best go for a walk

Anyway 3 cheers to Neil for not just asking the question but committing it to metal.


Think there is risk of loosing energy / temperature caus of you have much more pipe surface.
According to this loss it is difficult to calculate for two pipes...

And if pipes have minimum diffrences ...they talk 😉 against each other... 😞

Maybe the power flat is caused by that
Maybe??
Lets find out.

[Grumph]

Maybe??
Lets find out.

Don't remember what you're using for an ignition - but can you dial in some more advance at that point ?

[F5 Dave]

Gillette principle. Well, we have two pipes.
How about three? :laugh:

[Wos]

Don't remember what you're using for an ignition - but can you dial in some more advance at that point ?

If i remember correctly...a programmable ignition was on the playground:niceone:

Thats a good chance to get pipe temperatures more in ballpark ;)

A child is sound...if it is playing:niceone::first::clap:

[Flettner]

Don't remember what you're using for an ignition - but can you dial in some more advance at that point ?

An Ignitech and yes Ive advanced a lot off the pipes, made a world of difference, but if I try anymore around the transition, deto is waiting. After 7500 its fine, we are into it and retarding by the anyway.

[ken seeber]

Gillette principle. Well, we have two pipes.
How about three? :laugh:

So Mr F6, using the Gllette principle , Neil collaborated (made all the castings) with me for the 3 pipe system, so I guess it's now time for the 4 pipes..

355180355181355182

[F5 Dave]

Golly, things are accelerating and we haven't even put a Teflon glide strip anywhere yet. ;)

[Grumph]

Gillette principle. Well, we have two pipes.
How about three? :laugh:

You've still got some catching up to do Ken.

These things even use reed valves

[Wos]

An Ignitech and yes Ive advanced a lot off the pipes, made a world of difference, but if I try anymore around the transition, deto is waiting. After 7500 its fine, we are into it and retarding by the anyway.

Dear Flettner...hope you are away from to much advance at peak now...?:niceone:

And i hope your advance is not to high after pipe is in resonance...both could be killing by detonation or only overheating...

Further you can gain much overrev after peak power...3 dergree less 500 rev after peak and so on..since you arrived 6 degree. .than flatout.
not fitting for every setup exactly..but a guidline for carb without a shut off powerjet ;) ...carbs that not leaning after peak power any way

Whish good luck in continuing playing ;)

Wolfgang

[Flettner]

Dear Flettner...hope you are away from to much advance at peak now...?:niceone:

And i hope your advance is not to high after pipe is in resonance...both could be killing by detonation or only overheating...

Further you can gain much overrev after peak power...3 dergree less 500 rev after peak and so on..since you arrived 6 degree. .than flatout.
not fitting for every setup exactly..but a guidline for carb without a shut off powerjet ;) ...carbs that not leaning after peak power any way

Whish good luck in continuing playing ;)

Wolfgang

Is this acceptable Wolfgang? Remember the only dyno this bike has seen is my 'bum'.

[Mollihead]

For me the curve looks strange. At which RPM you expect your peak power?
Normally this should be at 15degree and falling down to 10 or lower behind the peak.

Is there a general offset in the graph?

[wobbly]

30* is too much off the pipe , I would never use more than 28* and that would only be in a situation where you never, ever, sit at part throttle down there.
And every engine , always , should have 15* of timing at peak power , then retard to about 10* at the rpm limit , depending upon how much overev is needed.
But flat lining near peak rpm stops the EGT from rising inexorably , forcing a richer main to be used to prevent overheating , not make power.
The " old " idea of winding in timing on rocket fuels , is nowhere near as powerful as an optimized petrol ignition curve with a suitably high CR.

[Flettner]

This is just a semi educated estimate, its' never been on a dyno yet.
Also never detonates, anywhere throughout the range.
Should I be retarding to 10 degees after 11500?
Do I need an 'expert' to tune it for me, perhaps? ��
Its only running BP98.
Because I cant get Gull E10 any more.
No rocket fuel.
Toridal head. About 0.5mm squish.

[Wos]

This is just a semi educated estimate, its' never been on a dyno yet.
Also never detonates, anywhere throughout the range.
Should I be retarding to 10 degees after 11500?
Do I need an 'expert' to tune it for me, perhaps? ��
Its only running BP98.
Because I cant get Gull E10 any more.
No rocket fuel.
Toridal head. About 0.5mm squish.

Not easy to help you flettner, cause so many factors are involved. With a dyno graph would bei easier

Do you have rev counter?

Where do you feel resonance begin?
Peak?
Your max rpm ever had?

If you give me data, i will do a sketch on hpi sofware.
Much easier to understand then talking endlessly ��

Your use is enduro...you need driveability in low rpm?

Then it could be better not to have 30 degree at low 2000 rpm or 3000...its a question if you sometimes need this rpms

Som engines feel well with 30 degree close under resonance others give you Signals like roughness, slight Vibrations...some only like 26 there...
Good thing is, some riders can feel this unhealthy behavior ��

If you have to much advance after reso begin, there are Vibrations too and it wont rev fast and smooth ;)

Steps of varying only 1 degree can often be recogniced by your ass ��...as we in germany say:killingme

Have a good one to all :)

Grüße Wolfgang

[Condyn]

I have been blindly using 30 degrees until 6800 rpm ( 9100 peak at 15 degrees ) all season. This is my first season on this build so we did not have time to fiddle with the curve much. The above comment by wobbly has me thinking about pulling some timing. Because we are cvt we stage at 6500 rpm and immediately shoot to 9100 in the first 5 feet as noted before. At the last event I staged at 7,000 rpm instead and as I am now reviewing the ignitech curve, this just so happens to be right at 27 degrees. We had improved 60 foot times at that event and better back half as well. The com is a whopping 18:1 and we run c25. This is 700cc. Somehow it does not detonate ever. Anyway, just dropping in to share, No questions today. I think I will spend some time playing with the initial advance on the dyno some more and In the field. The pipes have a massive volume so I am certain retarding the ignition during staging is going to help the launch. Maybe less compression could benefit as well. I have confirmed 15 degrees at peak is best with this combo on the dyno. 355187Any thoughts are welcome.

[Flettner]

Not easy to help you flettner, cause so many factors are involved. With a dyno graph would bei easier

Do you have rev counter?

Where do you feel resonance begin?
Peak?
Your max rpm ever had?

If you give me data, i will do a sketch on hpi sofware.
Much easier to understand then talking endlessly ��

Your use is enduro...you need driveability in low rpm?

Then it could be better not to have 30 degree at low 2000 rpm or 3000...its a question if you sometimes need this rpms

Som engines feel well with 30 degree close under resonance others give you Signals like roughness, slight Vibrations...some only like 26 there...
Good thing is, some riders can feel this unhealthy behavior ��

If you have to much advance after reso begin, there are Vibrations too and it wont rev fast and smooth ;)

Steps of varying only 1 degree can often be recogniced by your ass ��...as we in germany say:killingme

Have a good one to all :)

Grüße Wolfgang

Resonance starts at 7500, I used to have the advance still at 30 degrees there but my little freind detonation could be felt so now I start decreasing at 6500, det gone away.
To be fair Ive not put a timing light on it so the advance numbers may be not be entirely accurate. Must do that I guess at some point.
The engine is in bits at the moment getting fitted out with the new welded cylinder as seen above.
Next two meeting will have to be back with the air cooled cylinder. Perhaps even see a dyno before the water cooled cylinder is fitted permanent.
Exhaust 195, transfer 130, or as close as I can measure.
Bore and stroke an unfortunate 48 x 58.

[katinas]

Does anyone have the measurement from the disc to the piston face for the Aprilia RSA?

Thanks

Not accurately, approx 32-34mm.

[Wos]

Resonance starts at 7500, I used to have the advance still at 30 degrees there but my little freind detonation could be felt so now I start decreasing at 6500, det gone away.
To be fair Ive not put a timing light on it so the advance numbers may be not be entirely accurate. Must do that I guess at some point.
The engine is in bits at the moment getting fitted out with the new welded cylinder as seen above.
Next two meeting will have to be back with the air cooled cylinder. Perhaps even see a dyno before the water cooled cylinder is fitted permanent.
Exhaust 195, transfer 130, or as close as I can measure.
Bore and stroke an unfortunate 48 x 58.

Detos are not my friends my fellow flettner ��

And i miss max rpm you ever reached... inklusive overrev...if you dont know guessing could help for a first shot ��



Two things in relation to ignition timing can lead to detos...

To much advance in general
And how far you go with to much advance into powerband ...besides powerband risk is less ��

So.. let me think some time to cerate a more save timing curve for you ;)

Wolfgang

[Wos]

Resonance starts at 7500, I used to have the advance still at 30 degrees there but my little freind detonation could be felt so now I start decreasing at 6500, det gone away.
To be fair Ive not put a timing light on it so the advance numbers may be not be entirely accurate. Must do that I guess at some point.
The engine is in bits at the moment getting fitted out with the new welded cylinder as seen above.
Next two meeting will have to be back with the air cooled cylinder. Perhaps even see a dyno before the water cooled cylinder is fitted permanent.
Exhaust 195, transfer 130, or as close as I can measure.
Bore and stroke an unfortunate 48 x 58.

Detos are not my friends my fellow flettner 😉

Give me highest rpm you had...and if necessary guess 😉

Two things in relation to ignition timing can lead to detos...

To much advance in general
And how far you go with to much advance into powerband ...besides powerband risk is less 😉

So.. let me think some time to cerate a more save and effective timing curve for you ;)

Wolfgang

[Flettner]

11500, as seen in a glimpse on my Tiny Tach.

[Wos]

11500, as seen in a glimpse on my Tiny Tach.


Here we are Flettner

Dont mind about values under 1500...this area is only hard to influence in hpi programm

Black curve is my rebuild from foto of your curve youve showed us

Red new one from me to have a try...think nothing dangerous...in opposite should be much healtier against deto and too much heat in cilinder

Other pic shows values of my new curv

Let us know if you had a testride 😉

Grüße Wolfgang

[wobbly]

I have proposed on the FB group EngMod 2T Users , the we conduct a shootout to design the best pipe for a specific application.
This will help users understand how to most effectively use the sim , as well as see others attempts at pipe construction.
It was decided to do something " different " , not the usual 125/250 cc things that have large tech history to draw from.

I have bought a KR150RR bare engine that is used exclusively in Thailand scooter drag racing.
Im having trouble finding out what the rules actually are , but know they run VP Q16 fuel.
Once I have the rules nailed down , I will construct a sim , and people can give it there best shot at designing a pipe to suit.

When we have a " winner " I will build the engine to the complete sim and dyno it.
Anyone here who has info on these engines or wants to get in on the shootout , join the FB group ( Im an Admin ) or PM me on here.

[diesel pig]

My Goodness, I just looked up this VP Q16 fuel, on VP's own site and it has to be the meanest or 'best" fuel I have come across outside of pure methanol.

[husaberg]

My Goodness, I just looked up this VP Q16 fuel, on VP's own site and it has to be the meanest or 'best" fuel I have come across outside of pure methanol.
https://vpracingfuels.com/products/nitro-50-50-methanol-nitromethane-racing-fuel

[diesel pig]

https://vpracingfuels.com/products/nitro-50-50-methanol-nitromethane-racing-fuel

I have to admit I stopped reading after the Q16. It did my head in.

[pete376403]

My Goodness, I just looked up this VP Q16 fuel, on VP's own site and it has to be the meanest or 'best" fuel I have come across outside of pure methanol.

Is that the same cocktail miser they use in Laos nightclubs?

[wobbly]

C16 is oxygenated to hell , is full of lead and has a good RVP - perfect for a race 2T
Methanol has an inherently higher effective octane when run @ 20 % rich and can create more power , but also makes you blind and or dead.
Just plain greed , like the Chinese bastards that cut NZ baby formula with melamine or some such shit , the CCP gave that company's CEO a dose of Methanol quick smart.
About the only thing they are good at.

[Flettner]

Wos
Had the twin pipe AG out at a VMX meeting yesterday, didn't get round to fitting the video camera, perhaps next time. The little bugger goes.
But still that weird 'flutter' in the pipes as it comes on song or should I say when it flutters you are buggered as it just wont climb into the power. It seems totally random as to when it happens. Sometimes its just seamless other times a bit of a bitch. Definitely worse when hot.
Hanging my hat on the new water cooled cylinder although I have a few other tricks to try first.

[Wos]

Wos
Had the twin pipe AG out at a VMX meeting yesterday, didn't get round to fitting the video camera, perhaps next time. The little bugger goes.
But still that weird 'flutter' in the pipes as it comes on song or should I say when it flutters you are buggered as it just wont climb into the power. It seems totally random as to when it happens. Sometimes its just seamless other times a bit of a bitch. Definitely worse when hot.
Hanging my hat on the new water cooled cylinder although I have a few other tricks to try first.

Hope i am on right way
What you discricbe...
For me a sign the temperatures in pipe are staying to long to cool. Then pipe stucks to long time between reso entry and being really on song.

Exhaust gas temp on new kurve shoud be generally litle bit higher and after power peak a lot warmer to gain overrev...

For overrev you need a hot pipe and after shifting gear these heat stays in pipe for a second...

This could help further to be well on song seamlessly after shifting

Give new curve a chance...think you will feel very quick if something is better ��

Grüße Wolfgang

[Wos]

Wos
Had the twin pipe AG out at a VMX meeting yesterday, didn't get round to fitting the video camera, perhaps next time. The little bugger goes.
But still that weird 'flutter' in the pipes as it comes on song or should I say when it flutters you are buggered as it just wont climb into the power. It seems totally random as to when it happens. Sometimes its just seamless other times a bit of a bitch. Definitely worse when hot.
Hanging my hat on the new water cooled cylinder although I have a few other tricks to try first.

Hope i am on right way 😉
What you discricbe...
For me a sign the temperatures in pipe are staying to long to cool. Then pipe stucks to long time between reso entry and being really on song.

Exhaust gas temp on new kurve is generally litle bit higher and after power peak a lot warmer to gain overrev...

For overrev you need a hot pipe and after shifting gear these heat stays in pipe for a second...



This could help further to be well on song seamlessly after shifting 😉

Cilinder on new curve is running cooler everywhere to avoid detos or other overheating problems cilinder ...piston etc.

Give new curve a chance...think you will feel very quick if something better 😉

Grüße Wolfgang

[Flettner]

The twin port AG has no issues with detonation, at all.
The only time Ive had an issue was when I left full advance until 7500 and even then it was bearly noticable ( but it was there ). Since changing to reducing advance from 7500 to 6500 it has gone completely. It is surprisingly detonation proof, even when hot.

The surging Im experiencing is not detonation, for example I can let it happen indefinitely and it does no damage to the engine, just makes it hard to ride.

[Wos]

The twin port AG has no issues with detonation, at all.
The only time Ive had an issue was when I left full advance until 7500 and even then it was bearly noticable ( but it was there ). Since changing to reducing advance from 7500 to 6500 it has gone completely. It is surprisingly detonation proof, even when hot.

The surging Im experiencing is not detonation, for example I can let it happen indefinitely and it does no damage to the engine, just makes it hard to ride..

You told us before that there is no problem with detos after reducing to 6500 😉

Thats why i kept this point as maximums end 😉

building a curve is always a gamble...puzzle that we always should start from save side.

15 degree after peak power nowdays with programmable ignition seems to me much "under state of the art "

Other rpm points on curve without dyno only to do with many testing rounds with slightly diffrent curves.

Buy the way flettner... have fun and good luck fiddeling out 😀 I love it 😉

[Flettner]

Wos, you may well be right, 15 degrees may be too much and I look forward to playing with the curve on a dyno at some point.
In the mean time that is not my main problem. I have to sort out what these pipes are up to. Last pipes had a large joiner between the mid sections, these do not. I dont remember this issue with the old pipes. These new pipes certainly make more top end power with more accurate press tool sections.

[Wos]

Wos, you may well be right, 15 degrees may be too much and I look forward to playing with the curve on a dyno at some point.
In the mean time that is not my main problem. I have to sort out what these pipes are up to. Last pipes had a large joiner between the mid sections, these do not. I dont remember this issue with the old pipes. These new pipes certainly make more top end power with more accurate press tool sections.

Old pipe ...new pipe...dosent matter...you are collecting experience...can do conclusions for next needs ...

In combination of changing ignition you can even get more insight whats going on... worth doing it before thinking about other pipe...


Mid section? Cilindrical part? Belly?

Do you work with fos pipe calculation?
Very good start and easy with jan bros excel ;)

Belly diameter now...lengt from piston to end cone? ;)

If i had to deal with your twin x :)

Would calculation do with 50 cc ...go with small diameter/ shallow pipe ...resonance length 8500...9000 wide powerband for enduro use...

If i am completely wrong...dear other better speacialists here...tell me...tell us!! :not: ;) top!

Grüße from enduro fellow ;)

[Flettner]

So, what HP should we expect from an air cooled AG100 (125).
What is a sensible top end rev range for a 48 x 58 bore and stroke engine?
Wos, each pipe is loosely based on a KX65
Each outlet port nozzeled at approx 80% of port area, @ transfer just cracking open.

[Frits Overmars]

Resonance starts at 7500....Exhaust 195, transfer 130....Bore and stroke an unfortunate 48 x 58.Unfortunate? It would be worse the other way around. Now you've got a 105cc engine with decent angle.areas, sufficient for max.power at >11000 rpm. With bore and stroke 58 x 48 you'd have a 127cc engine with angle.areas limiting max.power rpm to perhaps 9000.
Summary: the long-stroke engine would be able to produce the same power, albeit at higher revs, but with less thermal load on the piston.
You could of course force the short-stroker to produce its max.power at higher revs with a shorter pipe , but BMEP would suffer and max.power would not be any better.
I think there is a simpler way of designing a pipe than basing it on a KTM 65SX. With your above values, a cylinder capacity equal to 50% of your 105 cc and an estimated exhaust duct length of 70 mm it would look like this.
355252

[Wos]

Did a Addition of the partial lengths firits showed us

859 mm pipe are about a peak resonance at 11000 rpm ...

If we calculate pipe with half engine capacity and half of its Horse power...volume of each pipe sinking to 50 percent too...a chance to get pipe temperature in ballpark ...I think

Hard to answer how much power ...

Stock 125 enduro or crosser bikes in early /mid 1980ties aircooled had max 28 hp...every horse more was a lie:psst:

[aljaxon]

hi chaps not posted on here for a while, been too busy making crap pipes.:facepalm: i'd like some pointers on a making a pipe for my 82cc aircooled motor 190/128, 50mm x 39.7mm (not by design) single ex port 6 transfers, crankcase reed intake. single gear variated. not a lot to go on i know but the power characteristics are the clutch bites at 9500 and the revs slowly rise to 9750 while the motor variates and then reaches full variation at around 10000 and then i would like it to reach max spead at 11500. i need zero over rev and nothing below the clutch bite point . so quite a narrow power band compared to pipes ive previously built. i could possible live with it revving to 11750.
i still havent forked out for engmod 2t yet due mainly to me not confident enough that i can input all the data accurately enough to give output of any value.
im making 3 pipes.
i.m wondering whether to aim peak power for max revs with a cliff after that or if thats a hard/impossible pipe to make + instead aim for smack bang in the middle of my rev range 9500 - 11500 ie 10500.
before i fitted this new clutch the motor would struggle to rev past 7000rpm. but now it doesnt have to operate at those revs and it flies

i know this is a how long is a piece of string question but id appreciate any pointers re percentages. its going to be around 750mm tuned length or slightly longer depending on what peak i aim for. start diameter 27mm.

[Condyn]

You just need to roll cones and try things. The following are things that I have found to work. It takes many attempts of dyno and field testing to get it nailed down
For a cvt pipe and the characteristics you are after, just make a simple 2 stage diffuser pipe to START with. You will likely not end that way. 30-31 percent header and keep your first diffuser shallow and long around 7 degrees. 2nd diffuser 15 or so degrees. 68 percent to end of diffuser. Take the total length of the diffuser and make 2/3 of it the first diffuser. Make your baffle cone around 25 degrees. If the power comes on too late make the first diffuser shorter and second longer so it opens to the 15 degree cone sooner.

[Wos]

Dear my teachers ;)

Never did a pipe for cvt...but this leads me to interesting questions ��

Is Single endcone/baffle best for highest output at small powerband spread?
Then it should fit on cvt...

25 degree looks to me not verry steep...but somewhere i read from a limit...

Which angle of baffle is biggest effective number if small spread and max power is goal

Are there other numbers the limit depends on?

Thanks to all!! ;)

Wolfgang

[wobbly]

The rear cone angle is interdependent upon two factors - the relationship between front side and peak/overev power , plus the belly diameter.
A 25* cone on a 100 diameter belly could be considered steep , but on a 140 Diameter pipe , well over 30* is getting " steep ".
The steeper the cone the less front side and overev is available , but peak is shifted upward - effectively narrowing the powerband.

I have been experimenting with two and three angle reverse taper rear cones.
These sacrifice a small amount of front side for a large increase in peak and overev power.
For a CVT, using this concept you would then lengthen the pipe , to bolster the power between peak torque and peak power, making it faster to hit the CVT lockup - by sacrificing the unnecessary overev.

[aljaxon]

You just need to roll cones and try things. The following are things that I have found to work. It takes many attempts of dyno and field testing to get it nailed down
For a cvt pipe and the characteristics you are after, just make a simple 2 stage diffuser pipe to START with. You will likely not end that way. 30-31 percent header and keep your first diffuser shallow and long around 7 degrees. 2nd diffuser 15 or so degrees. 68 percent to end of diffuser. Take the total length of the diffuser and make 2/3 of it the first diffuser. Make your baffle cone around 25 degrees. If the power comes on too late make the first diffuser shorter and second longer so it opens to the 15 degree cone sooner.

thanks condyn, i havent got enough time left on this planet to get it exactly nailed on. im an old git. i have a pal with a dyno but for my purposes it either works or it doesnt. i will gear to top speed and the fastest pipe wins.
those angles and proportions are almost exactly what i was told by wobbly would produce a good frontside pipe with no over rev. except the baffle cone was only 20 degrees. to get the baffle cone at 25 degrees i would need a long belly section.

i would have thought a longer belly does narrow the power band. but i know it doesnt always work out how you expect.

[aljaxon]

The rear cone angle is interdependent upon two factors - the relationship between front side and peak/overev power , plus the belly diameter.
A 25* cone on a 100 diameter belly could be considered steep , but on a 140 Diameter pipe , well over 30* is getting " steep ".
The steeper the cone the less front side and overev is available , but peak is shifted upward - effectively narrowing the powerband.

I have been experimenting with two and three angle reverse taper rear cones.
These sacrifice a small amount of front side for a large increase in peak and overev power.
For a CVT, using this concept you would then lengthen the pipe , to bolster the power between peak torque and peak power, making it faster to hit the CVT lockup - by sacrificing the unnecessary overev.


cheers wobbly, reverse taper as in going from from belly - sharpest cone - less sharp cone - even less sharp?

[wobbly]

Correct.
Here is an example for a Classic Roadrace bike

[husaberg]

Unfortunate? It would be worse the other way around. Now you've got a 105cc engine with decent angle.areas, sufficient for max.power at >11000 rpm. With bore and stroke 58 x 48 you'd have a 127cc engine with angle.areas limiting max.power rpm to perhaps 9000.
Summary: the long-stroke engine would be able to produce the same power, albeit at higher revs, but with less thermal load on the piston.
You could of course force the short-stroker to produce its max.power at higher revs with a shorter pipe , but BMEP would suffer and max.power would not be any better.
I think there is a simpler way of designing a pipe than basing it on a KTM 65SX. With your above values, a cylinder capacity equal to 50% of your 105 cc and an estimated exhaust duct length of 70 mm it would look like this.
355252

I think he is in the worse off position I fear Fletter transposed his bore and stroke.
I muse he has a 58x48mm bore and stroke.
Those AGS are short of cylinder stroke as std and pretty sure he put in a bigger pin as well.
They start of as 52x45.6 similar engine to DT100 MX100
They are really a scaled up 80cc.

[Flettner]

Unfortunate? It would be worse the other way around. Now you've got a 105cc engine with decent angle.areas, sufficient for max.power at >11000 rpm. With bore and stroke 58 x 48 you'd have a 127cc engine with angle.areas limiting max.power rpm to perhaps 9000.
Summary: the long-stroke engine would be able to produce the same power, albeit at higher revs, but with less thermal load on the piston.
You could of course force the short-stroker to produce its max.power at higher revs with a shorter pipe , but BMEP would suffer and max.power would not be any better.
I think there is a simpler way of designing a pipe than basing it on a KTM 65SX. With your above values, a cylinder capacity equal to 50% of your 105 cc and an estimated exhaust duct length of 70 mm it would look like this.
355252

It is 58 bore x 48 stroke.

[Betaversio]

Hello, question mainly for Frits and Jan,

I had a conversation with pipe-minded friend. We discussed how did you decide between two different power curves before a race, given specific gear ratios, weather conditions, and track characteristics. We were thinking how you did this when working at Aprilia team.

When designing something for a motor—perhaps in a simulator—you often have to decide what to build. Or when testing on a dyno and comparing 30 different power curves that look quite similar to the eye (one with peak power, another with better range), how did you choose between them?

I am familiar with your power range-concept. Instead of that, my friend suggested pipe design based on gear ratios and least missed area under ideal acceleration curve (what would be if motor is always at peak power). However, this approach doesn’t account for human factors, such as the need for mid-range and over-rev. While it’s possible to include these considerations, the result becomes a bit of a hocus-pocus calculation.

When simulating, I once started writing code to simulate a driver’s path around a track. I made drag racing version of it. I stopped working on track version because factors like varying pipe temperatures after corners and use of over-rev would have made the motor simulation inaccurate. This does seem to be only option, if it would be possible to make both track and motor simulation accurate enough.

Another possible shortcut is to optimize the engine using log data. For example, if the engine spends 4% of its time at 12,000–12,200 rpm and 5% at 12,600–12,800 rpm, these rpm ranges can be weighted accordingly to guide improvements. For me, this is most promising one, according to what is possible in normal tuner's resources. But, then there is problem that even when when we have two equal designs in this concept's, and power in different places in curve, pipes are not equally fast on track. :brick:

At least this is interesting... :facepalm:

If you others also have some thoughts, feel free to share.

Kind regards,
Antti

[Wos]

The rear cone angle is interdependent upon two factors - the relationship between front side and peak/overev power , plus the belly diameter.
A 25* cone on a 100 diameter belly could be considered steep , but on a 140 Diameter pipe , well over 30* is getting " steep ".
The steeper the cone the less front side and overev is available , but peak is shifted upward - effectively narrowing the powerband.

I have been experimenting with two and three angle reverse taper rear cones.
These sacrifice a small amount of front side for a large increase in peak and overev power.
For a CVT, using this concept you would then lengthen the pipe , to bolster the power between peak torque and peak power, making it faster to hit the CVT lockup - by sacrificing the unnecessary overev.

Thanks wobbly

Reverse 3 cone concept sounds to me as a combination of two worlds...for frontside keeping long resonance pipe length...and at powerpeak main actor is first very steep cone of baffle...gaining strong reflection there?

Does my picture fit?

Thank you very much!!! ;)

Wolfgang

[Frits Overmars]

I had a conversation with pipe-minded friend. We discussed how did you decide between two different power curves before a race, given specific gear ratios, weather conditions, and track characteristics. We were thinking how you did this when working at Aprilia team.
When designing something for a motor—perhaps in a simulator—you often have to decide what to build. Or when testing on a dyno and comparing 30 different power curves that look quite similar to the eye (one with peak power, another with better range), how did you choose between them?

I am familiar with your power range-concept. Instead of that, my friend suggested pipe design based on gear ratios and least missed area under ideal acceleration curve (what would be if motor is always at peak power). However, this approach doesn’t account for human factors, such as the need for mid-range and over-rev. While it’s possible to include these considerations, the result becomes a bit of a hocus-pocus calculation.

When simulating, I once started writing code to simulate a driver’s path around a track. I made drag racing version of it. I stopped working on track version because factors like varying pipe temperatures after corners and use of over-rev would have made the motor simulation inaccurate. This does seem to be only option, if it would be possible to make both track and motor simulation accurate enough.

Another possible shortcut is to optimize the engine using log data. For example, if the engine spends 4% of its time at 12,000–12,200 rpm and 5% at 12,600–12,800 rpm, these rpm ranges can be weighted accordingly to guide improvements. For me, this is most promising one, according to what is possible in normal tuner's resources. But, then there is problem that even when when we have two equal designs in this concept's, and power in different places in curve, pipes are not equally fast on track.Hello Antti, designing a pipe based on gear ratios is a guaranteed recipe for a bad relationship with the person who has to ride it. In racing conditions you will need quite some overlap between the gears and a well-developed engine can provide this; it should not need fiddling on the track. This hard-learned experience is one of the reasons I developed the Range concept.
For track conditions you adapt the gear box ratios and the final transmission ratio, not the power curve. Throttle response is important but this is not something you can develop on a common dyno. Overrev is also important but this comes with the engine; it is not something that you should work on at the track, apart from getting the carburation right.

[aljaxon]

if my rev range is 9500 to 11500 do i want to be aiming for a pipe designed to produce peak power at 11500? or just below that to allow the tiny bit of overrev to chip in? or bang in the middle of my rev range so i'm nearer to where the clutch bite point is?

[Frits Overmars]

if my rev range is 9500 to 11500 do i want to be aiming for a pipe designed to produce peak power at 11500? or just below that to allow the tiny bit of overrev to chip in? or bang in the middle of my rev range so i'm nearer to where the clutch bite point is?Design the pipe for the rpm that the blowdown angle.area and the transfer angle.area allow. That goes for any engine, direct-drive, shifted or CVT.
And make the clutch bite at the rpm of max.torque.

[wobbly]

Wos , the reverse cone scenario uses the idea that shallow rear cones help front side and overev capabiliity.
When using the reverse angle idea on the same tuned length , it looses a small amount of front side ,but the peak and overev is enhanced.
This is , I believe from observing the rear cone wave forms , due to a very early strong reflection that as usual would pump up the peak, but then the shallower
cone allows the engine to rev on alot better than it would were there a single steepish cone.
You can get the front side back with a longer TL , thus keeping the peak increase , but reducing the power in the overev.
No free lunch as usual.

[Betaversio]

Hello Antti, designing a pipe based on gear ratios is a guaranteed recipe for a bad relationship with the person who has to ride it. In racing conditions you will need quite some overlap between the gears and a well-developed engine can provide this; it should not need fiddling on the track. This hard-learned experience is one of the reasons I developed the Range concept.
For track conditions you adapt the gear box ratios and the final transmission ratio, not the power curve. Throttle response is important but this is not something you can develop on a common dyno. Overrev is also important but this comes with the engine; it is not something that you should work on at the track, apart from getting the carburation right.

Thank you for reply,

If I understood it right, at some point you did try to design motor based on gear ratios, but then it did not work out well. After that you went to this simple power range-model. Then you just somehow find this 1.4 range to be good enough, without any complicated math's. And there was no any hard-calculation-model determining what is good power curve and what is not.

Antti

[Wos]

Hello Antti, designing a pipe based on gear ratios is a guaranteed recipe for a bad relationship with the person who has to ride it. In racing conditions you will need quite some overlap between the gears and a well-developed engine can provide this; it should not need fiddling on the track. This hard-learned experience is one of the reasons I developed the Range concept.
For track conditions you adapt the gear box ratios and the final transmission ratio, not the power curve. Throttle response is important but this is not something you can develop on a common dyno. Overrev is also important but this comes with the engine; it is not something that you should work on at the track, apart from getting the carburation right.

No rider is a machine...no human is...so give us the chance/strengt in live/ race to get out of our mistakes ;)
Thats best you could do ... :)

[aljaxon]

Design the pipe for the rpm that the blowdown angle.area and the transfer angle.area allow. That goes for any engine, direct-drive, shifted or CVT.
And make the clutch bite at the rpm of max.torque.
cheers frits, i used janbros excel and all seemed good

. ......... ,,,,,, ...... . STA ....... . Target ...... , % ....... ' Out of breath RPM


BLOWDOWN ....... 5.79 ....... 4.11 ....... 40.8 ....... 11265

TRANSFER ....... 50.13 ........ 40.04 ....... 25.2 ....... 10017

that took some time to format correctly hence the punctuation

...

thats if i aim for a realistic 8 bmep which could give 11.7bhp. its saying my torque will be maxed at 8000.

and im guessing from those numbers my max power revs is in between the 11265 and 10017.

if i wanted to make a FOS pipe but with a narrower powerband to suit the the cvt can you recommend which angles to change? or lengths to adjust?

[Frits Overmars]

if i wanted to make a FOS pipe but with a narrower powerband to suit the the cvt can you recommend which angles to change? or lengths to adjust?Yes I can: stick to the FOS pipe dimensions. Trying to make the power band narrower will reduce power instead of enhancing it.
For example, you could make the rear cone steeper which would yield a shorter, fiercer return pulse. But such a fierce pulse would develop into a shock wave before it reaches the exhaust port, and shock waves are not very good at shoving mixture back into the cylinder.
I know you are sceptical: try it for yourself and let us know what you found :shifty:.

[aljaxon]

so you are saying even a 1 degree change in angle to the fos pipe wont make a sharper powerband?
its like you are saying your fos pipe is a one size fits all which surely cant be right, if it was the perfect pipe then everyone would be using it. btw ive made 2 fos pipes and ive got one fitted to the bike at the minute.


its looking more and more like im going to have to fork out for engmod 2t
ive been chatting with a pal who has it and he's been making adjustments to pipes and seeing the changes

[Frits Overmars]

so you are saying even a 1 degree change in angle to the fos pipe wont make a sharper powerband? That is not wat I was saying. You can make the power band a whole lot narrower if you wish, but it won't improve power; it will cost power, as I already told you. You don't have to take my word for it, but then you'd better stop asking and start building.
The other day you wrote: "i havent got enough time left on this planet....im an old git".
Well, I'm an old git too; do you think I fancy wasting my time over this?

[Condyn]

I feel comfortable in being Frits muscle on this one. He has never once stated it is the holy grail, final tuned pipe you will ever need. His concept literally says it is for getting beginner tuners on their way. I have made a few FOS pipes and they taught me a lot. To believe any of us can give you a perfect scenario pipe design is foolish. There are too many variables. Engmod still needs good inputs, and it is a design tool, not the sorcerers stone. You will be disappointed with engmod if you do not real world test along side of it, until you know you are feeding the correct information.

While on the topic, my personal belief with the simulation pipe challenge is that more than the top pipe design should to be dyno tested in conjunction with the sim results. Showing everyone how accurate reality replicates the sim on multiple designs would be beneficial to all parties. I would be happy to laser cut and build some of the pipes, but I would not be happy to ship them to NZ lol.

[koba]

I have proposed on the FB group EngMod 2T Users , the we conduct a shootout to design the best pipe for a specific application.
This will help users understand how to most effectively use the sim , as well as see others attempts at pipe construction.
It was decided to do something " different " , not the usual 125/250 cc things that have large tech history to draw from.

I have bought a KR150RR bare engine that is used exclusively in Thailand scooter drag racing.
Im having trouble finding out what the rules actually are , but know they run VP Q16 fuel.
Once I have the rules nailed down , I will construct a sim , and people can give it there best shot at designing a pipe to suit.

When we have a " winner " I will build the engine to the complete sim and dyno it.
Anyone here who has info on these engines or wants to get in on the shootout , join the FB group ( Im an Admin ) or PM me on here.

This is a great Idea!

[wobbly]

The initial proposal is to dyno test the " best " pipe with all the other variables of the sim replicated in hard parts. This will show the veracity of the simulation , but I believe even more will be learned from what is not right.
It all depends upon " the money " , of course - its going to cost plenty to even collect all the parts needed , then a huge amount of work to actually build the thing.
Several people have offered to build pipes , but even in this scenario , there are hours of CAD work to generate the .dxf files for laser cutting the segments.
In the mean time I am testing Neels code update before distribution and the first technical description of a page of the proposed sim has been posted on the FB EngMod site.
Go have a look.

[Condyn]

Yes yes, easier said than done. It will be interesting to see how it all pans out. I will take a look on farcebook.

[JanBros]

cheers frits, i used janbros excel and all seemed good

. ......... ,,,,,, ...... . STA ....... . Target ...... , % ....... ' Out of breath RPM


BLOWDOWN ....... 5.79 ....... 4.11 ....... 40.8 ....... 11265

TRANSFER ....... 50.13 ........ 40.04 ....... 25.2 ....... 10017

that took some time to format correctly hence the punctuation

...

thats if i aim for a realistic 8 bmep which could give 11.7bhp. its saying my torque will be maxed at 8000.

and im guessing from those numbers my max power revs is in between the 11265 and 10017.



who or what is "it" ?

"out of breath rpm" = rpm after which your max torque will not rise anymore. so the predicted rpm of max torque.
your STA's say 10000 for the transfer's and 11200 for the Bd , not 8000. so your engine has too much A.area if you are shooting for 8BMEP (to protect the engine) ? or raise the BMEP ? or other things are not correct/entered right.

[aljaxon]

who or what is "it" ?

"out of breath rpm" = rpm after which your max torque will not rise anymore. so the predicted rpm of max torque.
your STA's say 10000 for the transfer's and 11200 for the Bd , not 8000. so your engine has too much A.area if you are shooting for 8BMEP (to protect the engine) ? or raise the BMEP ? or other things are not correct/entered right.

the figure on the exhaust new sheet in box 14 E is saying 8000 rpm. i thought because it was yellow it was working out this figure from my port maps.

i didnt realise it was the figure that i'd entered myself in the first Data sheet in box 20 E.

and this is why i am reluctant to invest in engmod 2t because i dont trust myself to enter all the info correctly.


i dont know what the actual hp or torque is or at what rpm. this is a different project on an identical bike to the first one i did a couple of years ago. that had 10.8bhp at 9470 so i just entered that. ill try having a better guess and enter updated figures.


as for the bmep if i enter 8 box 40 D on exhaust new it gives bhp of 13.9 which i think is too optimistic for my porting and pipe building skills.
ive just entered 7 and it gives a more realistic bhp of 12.2bhp which by the time it reaches the back wheel is probably 11 which im guessing this is the case in reality, although i am hoping for more.
if i enter 7 bmep and 9500 max torque and rpm power i get out of breath rpm as blowdown 13171 and transfer 10938.

should i be aiming to up the figures im entering in the data sheet for power and torque rpm so they bring down the out of breath rpm to a closer match?

edit if i enter 10000 as my peak rpm and torque and then i enter 8.1 as my bmep i get out of breath blowdown 11105 and transfer 9933. ive got a single ex port at 68% of bore so cant really go much bigger. maybe ive gone to big on the transfers?

[aljaxon]

That is not wat I was saying. You can make the power band a whole lot narrower if you wish, but it won't improve power; it will cost power, as I already told you. You don't have to take my word for it, but then you'd better stop asking and start building.
The other day you wrote: "i havent got enough time left on this planet....im an old git".
Well, I'm an old git too; do you think I fancy wasting my time over this?

i can sympathise you being a fellow member of the old git club and thats why instead of going to the trouble to reply in depth i was hoping you'd say i/we found a narrower belly or sharper rear cone gives a narrower power band. or a longer or shorter header etc. jennings and bell suggest sharper angles give narrower power bands. and the freely available calcs that ask you for what type power delivery usually 3 types, wide normal and gp bike suggest the same. i know those are old and out of date?
i built a 3 pipes last year thin normal and fat - same proportions and lengths and the fat one worked best even though it shouldnt have. i posted about it on here. very little over rev on any of them. i built a further 3 pipes but didnt really come to any clear conclusions as to what was doing what. i altered the rear cone of one to a 3 stage but the difference was minimal. i appreciate you dont want to waste any of your time on this frits. i am grateful of your design, ive built 4 of your pipes and im running one now. i just wanted to tweak it a bit and who better to ask than the man who's design it is.
i realise making pipes without testing them on a sim is hard work and time consuming. i should be using eng mod then making a straight pipe to test on a dyno and then road test. but im just an old bloke whos messing about with mopeds in his shed cos theyre cheap and im not gonna kill myself on them at breakneck speeds. i think ive finally realised im out of my depth on here. asking questions that probably cant be answered simply.

[aljaxon]

I feel comfortable in being Frits muscle on this one. He has never once stated it is the holy grail, final tuned pipe you will ever need. His concept literally says it is for getting beginner tuners on their way. I have made a few FOS pipes and they taught me a lot. To believe any of us can give you a perfect scenario pipe design is foolish. There are too many variables. Engmod still needs good inputs, and it is a design tool, not the sorcerers stone. You will be disappointed with engmod if you do not real world test along side of it, until you know you are feeding the correct information.

While on the topic, my personal belief with the simulation pipe challenge is that more than the top pipe design should to be dyno tested in conjunction with the sim results. Showing everyone how accurate reality replicates the sim on multiple designs would be beneficial to all parties. I would be happy to laser cut and build some of the pipes, but I would not be happy to ship them to NZ lol.

condyn i only wanted to know in which areas to tweak the FOS design to give a narrower power band. and when frits says it cant be tweaked for my desires then im trying to wonder why? surely any pipe desing can be tweaked to become better? possibly at the expense of power elsewhere? i havent got engmod2t. im only a diy tuner working on a shoestring budget playing with mopeds. i actually enjoy making pipes having taught myself to tig weld. but i know the time should be spent doing other stuff in my life. a bit like busying myslef on here when i should be doing the dishes or decorating......

[wobbly]

Aljaxon, I think you need a lot more in depth study on your knowledge base, and we need alot more info.
When you say "i enter 8.1 as my bmep i get out of breath blowdown 11105 and transfer 9933. ive got a single ex port at 68% of bore so cant really go much bigger. maybe I've gone to big on the transfers?".
You have the whole concept back to front , if the Blowdown rpm is 11105 that is way in excess of the Transfers at 9933 , so how the hell can the transfers be " too big ".
And regarding the pipe geometry , every section of the pipe has a specific area of influence on the powerband shape , and all of them can be mixed and matched to gain a specific characteristic.
As the rear cone is made steeper its reflected return wave is increased in amplitude, and reduced in bandwidth.
This has a corresponding identical effect on the resultant power , with reduced front side, increased peak power, and reduced overev.
But that's just one element , there are a dozen more , so me trying to help with so little detailed specifications, is a lost cause.

[JanBros]

Aljaxon, I think you need a lot more in depth study on your knowledge base
You have the whole concept back to front

this.
you do not design ports and than start playing with the BMEP end rpm's to get the numbers right.
You decide what (BMEP) you want from the engine at which rpm's, and only than you start to draw port's to match the STA numbers.

If you want to use a specific cylinder, you can try and play with BMEP and rpm's to figure out what it might be capable of, but don't expect it will always be able to match what you want from it.

[Flettner]

Off to NZ Cylinders for Nikasil.

[Wos]

:wings: hell of a welding job! :)

How will the power valve sildes be driven ?

[Flettner]

:wings: hell of a welding job! :)

How will the power valve sildes be driven ?

Like this, this is one is out of my Autogyro engine, I built it years ago and seems to work fine. Via the Ignitech ignition to control it.

[porttiming124]

Hello everyone.
Concerning the calibration of the dyno egts.
In my land and sea software I can reset the temperatures.
I would like to validate that the probes all read the same temperature at the top.
I thought about making a small box preheat to 600Celcius for example and I could fix all the probes.
Currently on a 2 cylinder engine I reverse the probes from one side to the other and I do the temperature differential but I would like them calibrated.
I'm curious to know how you did it? THANKS

[aljaxon]

this.
you do not design ports and than start playing with the BMEP end rpm's to get the numbers right.
You decide what (BMEP) you want from the engine at which rpm's, and only than you start to draw port's to match the STA numbers.

If you want to use a specific cylinder, you can try and play with BMEP and rpm's to figure out what it might be capable of, but don't expect it will always be able to match what you want from it.

i did an identical cylinder 176 124 2 yrs ago and entered it into your excel based on that guesed i wanted 190 130 to up the peak power rpm. so i ported it to 189 128 and made a port map and entered it into your excel to see what was what and to see what needed tweaking.
im not fussed what the bmep or hp or torque is. i just need to know the optimimum rpm my current porting has so as to make a pipe matched to the same rpm. if my ports need tweaking a tiny bit then im happy to do that but im not too sure on how to interpret the results on the excle. . is there any way i can upload the excel or would a screenshot do?

[aljaxon]

Aljaxon, I think you need a lot more in depth study on your knowledge base, and we need alot more info.
When you say "i enter 8.1 as my bmep i get out of breath blowdown 11105 and transfer 9933. ive got a single ex port at 68% of bore so cant really go much bigger. maybe I've gone to big on the transfers?".
You have the whole concept back to front , if the Blowdown rpm is 11105 that is way in excess of the Transfers at 9933 , so how the hell can the transfers be " too big ".
And regarding the pipe geometry , every section of the pipe has a specific area of influence on the powerband shape , and all of them can be mixed and matched to gain a specific characteristic.
As the rear cone is made steeper its reflected return wave is increased in amplitude, and reduced in bandwidth.
This has a corresponding identical effect on the resultant power , with reduced front side, increased peak power, and reduced overev.
But that's just one element , there are a dozen more , so me trying to help with so little detailed specifications, is a lost cause.


cheers for reply wobbly. i just wanted the narrowest powerband pipe ever made peaking around 10500. maybe max torque at 10000, i can sort the tuned length out myself.
ive made the FOS pipe (a few times) which is said to be a good starting point. so i now want to tweak it to suit my purposes but frits says it cant be tweaked unless it will produce less power.

maybe thats less peak power but if the narrower power band has MORE power at the start and finish then thats surely better. ie a better curve to suit my purposes.

to my mind i can visualise sharper angles on the diffuser and rear cone separated by a longer belly. i would love this to be confirmed before i waste loads more time building it to find out its a dud.

i dont know if ive worded the b;lowdown and out of breath rpm. its all taken off janbros excel sheet. im not bothered about power numbers. just the rpm my motor works best at so as to match a pipe to it.
at the moment the thing flies. so im not too far off.

[aljaxon]

this.
you do not design ports and than start playing with the BMEP end rpm's to get the numbers right.
You decide what (BMEP) you want from the engine at which rpm's, and only than you start to draw port's to match the STA numbers.

If you want to use a specific cylinder, you can try and play with BMEP and rpm's to figure out what it might be capable of, but don't expect it will always be able to match what you want from it.

yeah i dont expect any of the power figures to be achieved in reality. they are largely immaterial. im just interested in finding the rpm my motor works best at to build a pipe to it. and if your excel reports a major flaw in my porting then i will look at that.

[JanBros]

yeah i dont expect any of the power figures to be achieved in reality. they are largely immaterial. im just interested in finding the rpm my motor works best at to build a pipe to it. and if your excel reports a major flaw in my porting then i will look at that.

the excel only calculates the time-area's of the port's and says nothing else about for example the transfer ducts or other determining aspects of an engine's power.

without actual numbers, it's hard to determine any power figures or rpm's based on the excel. for example : if you know the rpm of max power and you enter all the data correct, you can "predict" the max power the ports can deliver by adjusting the BMEP till the STA-numbers match for the known rpm of max power (or, at least the lowest target of transfer or blowdown , because it will not be able to keep up for the higher one). but that tell's you nothing of the power the complete engine can deliver.

I feel like you want simple straight answers for question's that do not have simple straight answers.

[aljaxon]

the excel only calculates the time-area's of the port's and says nothing else about for example the transfer ducts or other determining aspects of an engine's power.

without actual numbers, it's hard to determine any power figures or rpm's based on the excel. for example : if you know the rpm of max power and you enter all the data correct, you can "predict" the max power the ports can deliver by adjusting the BMEP till the STA-numbers match for the known rpm of max power (or, at least the lowest target of transfer or blowdown , because it will not be able to keep up for the higher one). but that tell's you nothing of the power the complete engine can deliver.

I feel like you want simple straight answers for question's that do not have simple straight answers.

i just wanted to know what rpm my ports are currently best suited for. and i thought thats what your software is for? obvioustly as you say it cannot take into account transfer tunnels etc so at the end of the day its only going to be a rough guide. but a rough guide is better than nothing?

if i raise all the transfers by 0.3mm i get this
https://live.staticflickr.com/65535/54189823040_2e7201229a.jpg

in the above pic the blowdown and the transfer sta's nearly match thats at 8 bmep if i lower the bmep figure the out of breath rpm goes up quicker for the blowdown than the transfer. do i need to input my actual bmep? if so then i need to put the bike on a dyno.

i thought this was a tool to help me work out whether my porting was good to go without using a dyno and just to make educated guesses.

so can i use the excel by adjusting the bmep and the offset of the transfers until i get the out of breath figures the same for the rpm that i want peak power for?

[Frits Overmars]

you do not design ports and than start playing with the BMEP end rpm's to get the numbers right.

so can i use the excel by adjusting the bmep and the offset of the transfers until i get the out of breath figures the same for the rpm that i want peak power for?Al, do you read the answers to your questions?

[JanBros]

i just wanted to know what rpm my ports are currently best suited for. and i thought thats what your software is for?
no , the software is for knowing how to make the ports based on what BMEP you are after at which rpm. not the other way round.

and only if you have accurate data you can make an educated guess.
if you don't have accurate data, it's like a hand-calculator. You know what you want the outcome to be but not how to get there. if you want the outcome to be 10500 (your desired rpm) you can enter 10 x 1050 and it will be correct. you can also enter 100 x 105 and it will be also correct. or 10000 + 500, or ....
the 2 missing numbers for the hand-calculator are BMEP and rpm and as shown above, you can enter very different values and still get "a correct answer". As long as you have 2 variables you can only make wild guesses. you need to get it down to 1 variable to make an educated guess. for example : know the rpm of max power, and than you can guess what BMEP and from that what HP to expect. But that rpm is dependant on your exhaust and you are going to change your exhaust, so even that rpm isn't accurate enough.

it comes down to one thing : trial and error, and if you start from the wrong side, you are going to make more error's. start from the correct side and get accurate data and you will get your answer much faster. but either way, you will have to find the correct answer yourself. People here have given you more than enough advise to get to the correct answer, it's up to you to aply it.

[wobbly]

EngMod works exactly the same way , you enter the bmep ( HP ) you want at a specific rpm , and it analyses what you actually have Vs what you want.
You then do a series of changes to the ports to try and match the desired result you have entered as a baseline..

[wobbly]

The pipe design shootout has started on the EngMod FB page for the Thai KR150 drag race engine. All the sim factors are explained, as well as the rules and the .pack file is available.
If you are a user , then get into it.
I have submitted my pipe , and have started on the engine build for dyno verification , once the competition is finalized.

https://www.facebook.com/groups/551011593550635/?hoisted_section_header_type=recently_seen&multi_permalinks=556769229641538

[aljaxon]

. removed post

[aljaxon]

EngMod works exactly the same way , you enter the bmep ( HP ) you want at a specific rpm , and it analyses what you actually have Vs what you want.
You then do a series of changes to the ports to try and match the desired result you have entered as a baseline..

thats basically what im doing. as i up the bmep it shows my motor is out of breath at a lower rpm. by moving the bmep figure up or down i can see how my porting is coping or not coping and how it needs tweaking. i previously got the blowdown and transfer sta's mixed up. i told you before im an idiot. and then i posted i needed 0.3mm in height to get everything matched at my desired rpm.

thanks wobbly.

[aljaxon]

The pipe design shootout has started on the EngMod FB page for the Thai KR150 drag race engine. All the sim factors are explained, as well as the rules and the .pack file is available.
If you are a user , then get into it.
I have submitted my pipe , and have started on the engine build for dyno verification , once the competition is finalized.

https://www.facebook.com/groups/551011593550635/?hoisted_section_header_type=recently_seen&multi_permalinks=556769229641538

has that kr150 got a real narrow powerband by any chance? :laugh:

i have in the past been guilty of taking a pipe design and multiplying all the lengths by a percentage to get the tuned length to what i require so as to keep all the sections in proportion to each other. and ive also done the same with the diameters to get the start diameter the same as mine and so all the diameters are still in the same proportion. the only thing that changes is the angles whichj have to due to basic maths.
my pal has kindly entered a few of these in EngMod with good and interesting results but based on a very simple (similar to mine) motor and keeping that a constant.
i was just wondering if what im doing has any merit or do i need my exact engine set up. or for a hobbyist working out of a shed (whos posting on the wrong forum i admit) is that near enough for what i need? at the end of the day i will be making a pipe so i look at it like anything to help me narrow down its design is better than nothing.

i have previously trawled and searched this thread and saved all the photos of pipe designs (mostly yours lol) and mostly for the rs 125.

[aljaxon]

no , the software is for knowing how to make the ports based on what BMEP you are after at which rpm. not the other way round.

and only if you have accurate data you can make an educated guess.
if you don't have accurate data, it's like a hand-calculator. You know what you want the outcome to be but not how to get there. if you want the outcome to be 10500 (your desired rpm) you can enter 10 x 1050 and it will be correct. you can also enter 100 x 105 and it will be also correct. or 10000 + 500, or ....
the 2 missing numbers for the hand-calculator are BMEP and rpm and as shown above, you can enter very different values and still get "a correct answer". As long as you have 2 variables you can only make wild guesses. you need to get it down to 1 variable to make an educated guess. for example : know the rpm of max power, and than you can guess what BMEP and from that what HP to expect. But that rpm is dependant on your exhaust and you are going to change your exhaust, so even that rpm isn't accurate enough.

it comes down to one thing : trial and error, and if you start from the wrong side, you are going to make more error's. start from the correct side and get accurate data and you will get your answer much faster. but either way, you will have to find the correct answer yourself. People here have given you more than enough advise to get to the correct answer, it's up to you to aply it.


i have been entering my desired rpm. and then seeing if the ports work at that rpm? and by shuffling the bmep figure up or down i can see at what revs the sta's match and that is basically the optimum rpm?

[Frits Overmars]

i have in the past been guilty of taking a pipe design and multiplying all the lengths by a percentage to get the tuned length to what i require so as to keep all the sections in proportion to each other.That's good, provided the original pipe design was good.


ive also done the same with the diameters to get the start diameter the same as mineThat would be good if your start diameter was good. Chances are that it's not.


i was just wondering if what im doing has any merit or do i need my exact engine set up. or for a hobbyist working out of a shed....
is that near enough for what i need?Of course you need your exact engine setup. 'Near enough' doesn't cut it. If you do not provide exact input data, you will get rubbish output data, no matter how sophisticated the applied software is. (and don't blame the shed. You should see the places from which we sometimes have to work.)


anything to help me narrow down its design is better than nothing.And then you question what you are being offered.

[aljaxon]

i know im asking lots of questions but i honestly dont know where else to ask them.

in mind i am thinking the first diffuser or the bit of the diffuser nearest the header influences high up the rev range. possibly past peak - overrev? so a tiny bit further away from that influences peak power rpm. and the very end of the baffle cone influences peak power rpm?
so if i simply make these two areas sharper angles and make the rest shallower i am utilising the energy available in the pipe at the rpm i desire. the sharper angles get the biggest lunch.... at the expense of power elsewhere which is what i want for my cvt type motor

ive just done a design with this shape plus with an extra long belly stealing length from the baffle cone and my pal is going to run it in engmod to see if the theory holds with his limited porting.
id love to see a pipe design somewhere aimed at cvt. ive tried searching on here and using google to no avail.

im guessing the modern scooter boys with their stage 6 stuff would benefit from a pipe designed around the narrow rpm so maybe i can "steal" some ideas from the pipes they use?

[wobbly]

The KR150 used in Thai drag racing is actually a 180cc as they must use the stock 59mm piston ( dumb as nothing good is available off the shelf ) but everything else is
open.
They run a CNC made 65.5 stroke ( +11mm ), and the cylinder has the Kawasaki KIPS system , where only the ( highest ) Auxiliary ports have a PV.
For the pipe shootout the Aux ports have been returned to the " normal " lower than the main duration and the KIPS system is disabled, as there is no option for this in EngMod and its what is done in reality.

The gearbox ratio's are not well spaced , and the engine is held at around 7000 rpm on the line , where they dump the clutch and go WOT.
Thus front side power has to be built into the pipe, as the PV is only partially effective , but it needs to have overev out to a lunatic 13500 ( 29m/s) to enable the shortest gear possible.
Not a narrow range port/pipe setup at all.

[husaberg]

The KR150 used in Thai drag racing is actually a 180cc as they must use the stock 59mm piston ( dumb as nothing good is available off the shelf ) but everything else is
open.
They run a CNC made 65.5 stroke ( +11mm ), and the cylinder has the Kawasaki KIPS system , where only the ( highest ) Auxiliary ports have a PV.
For the pipe shootout the Aux ports have been returned to the " normal " lower than the main duration and the KIPS system is disabled, as there is no option for this in EngMod and its what is done in reality.

The gearbox ratio's are not well spaced , and the engine is held at around 7000 rpm on the line , where they dump the clutch and go WOT.
Thus front side power has to be built into the pipe, as the PV is only partially effective , but it needs to have overev out to a lunatic 13500 ( 29m/s) to enable the shortest gear possible.
Not a narrow range port/pipe setup at all.
Do the rules define the std gear ratios?
The reason I ask is there are lots of stuff on the net for cr sets for all sorts of the weirdo Asian stuff...

[aljaxon]

And then you question what you are being offered.

lol i wasnt aware id been offered anything apart from you saying the FOS cant be tweaked re sharper baffle cone unless it gives less power, and wobbly suggested a sharper baffle cone can give more power at the detriment to over rev and peak which im happy with. and that there are multiple other asspects which can reduce power band width.

i got my kind pal to enter a modifictaion to a pipe in his engmod purely guessing which part of the diffuser to sharpen the angle, and to sharpen the last bit of the baffle cone and it DID produce a much narrower power band but also lost out at the top. the curve actually followed the front side almost identically which amazed me. we have been inputting pipes designed for tzr's and rs125 etc downsized to my start diameter and his which are 26mm and 27mm id. the port effective area is 620mmsq which is effective diameter of 28mm. the tract is 24.5mm long so it reduces from 28mm to 26mm over 24.5mm length. the bore is 50mm. the cylinder architecture is such that it has a big threaded nut that goes around the header to secure it in the cylinder. even with it machined so its thin as fook. (apologies for technical term) i can still only get 26mm id. the lengths i need to go to to get the pipes start diameter to be spot on are too lengthy. if it was a race bike with every fraction of hp targetted then maybe id do it. but there are many more priorities ie leaking roof needs fixing first.

according to FOS design i need a 29.3mm D1 but my 82cc is that low in tune single ex port only 68% of bore width and not maxed very cup cake shaped. , plus heavily over square 50mm x 41.8mm i reckon i could get away with calling it 70cc's then that brings D1 into my 26mm territory. i can feel frits frowning.

this is the kind of thing ive been doing to pipe designs ive stolen off this thread. . shortening and reducing by percentage to suit my new tuned length and start diameter. the angles of each section change from original which cannot be helped if you keep same percentage diameters. https://live.staticflickr.com/65535/54200214498_353a44f869_z.jpg


i borrowed one pipe design and downsized it which gave a lovely wide mushroom head type power curve, perfectly symmetrical at the peak when run in engmod combined with a motor that was very basic in comparison to the intended pipe.
sadly exactly the opposite of what i currently want.

all i need is an example of a pipe thats ok with a cvt set up and i can adjust it to suit my needs. but i cant find one anywhere.

[wobbly]

The Thai guys make special 1st and 2nd gears for the drag bikes.
I will have the ratio numbers over the weekend to compare.

[wobbly]

KR150 has stock 1st = 10/27 , drag race for light weight has 10/24 or heavier = 10/25
Second is stock 17/29 with drag race special 17/28 available.

[Storbeck]

Does anybody know a decent cheap/free program for analyzing large data files?

I have a crude water brake dyno, collecting data using an Aem Evo 4. Raw data from load cell through amplifier into an analog input on the evo4 and then I also can log RPM, egt, cht.

The raw load cell data captures the variation thoughout a single stroke, information I don't need, but I need to log at a high rate to avoid aliasing in the torque data then I just do a rolling average in post processing.

The Aem software does not lend itself well to this sort of thing, so currently doing it in Excel....which is clunky.

I have plans to improve all of this in the longer term, but in the mean time I'm more interested in doing development on my engine than taking on a dyno control project, so I can make it work with Excel clumsily but if there is some other readily available software out there that can do a little bit of post processing and just conveniently plot graphs with good functionality to zoom in and out and look at sections of data that would make things a lot easier.

I'm dealing with CSV's with something like 400,000 lines.

[Noxin]

Can you please upload one of your files somewhere where we can take a look at it?
I'm working on my own dyno software right now, so maybe I can fix something.

[lohring]

There are several dyno data loggers with software that can record data from a water brake. I'm familiar with Performance Trends (https://www.performancetrends.com/dtm-dyno.htm) on an inertial dyno, but Your Dyno (https://yourdyno.com/product/standard-water-brake-engine-dyno-kit/) has a water brake system as well.

Lohring Miller

[Storbeck]

Can you please upload one of your files somewhere where we can take a look at it?
I'm working on my own dyno software right now, so maybe I can fix something.

I'll see if I can figure out how to do that but I don't think the data will be much interest to you, it's just time, rpm, load cell voltage and a couple of temps from a very old fashioned old snowmobile engine. Logged at 1000Hz for a few minutes.

Lohring thank you for your suggestions I'm familiar with both of those and I'm really not in need (nor have the budget for) dyno hardware or "dyno software" right now.

I just need a convenient way to look at graphs of large files.

I'm pretty sure python would do it but then I have to learn python, which I wouldn't mind doing but that's a project in it's own and I just want an easy way to look at graphs that I can move around and zoom in and out without having to go through a bunch of dialog boxes and wait for laggy software to catch up as I am currently doing with excel.

[wobbly]

Python is a well used industry standard so I would go onto a nerd site somewhere and ask if someone with knowledge would look at your file and do whats needed.
The other thing is there are also plenty of people who can get into the back end of Excel and help with the clunk.

[Flettner]

So how much exhaust port area is needed below the transfers opening? Some, none or lots?

[F5 Dave]

Well none is needed as long as you had ample to fully evacuate the cylinder before that point so pressure doesn't use the transfers as temporary exhaust ports.
Usually unobtanium.

Think that was point of FOS cylinder.

How did that actually go btw?

[Noxin]

I just need a convenient way to look at graphs of large files.


Just send a sample file to me. I need something to wrap my head around while waiting for Santa..

[Wos]

So how much exhaust port area is needed below the transfers opening? Some, none or lots?

This is the story frits and jan did at the last days of 2 stroke gp by lifting exhaust downside...

They lifted it only a little and it worked well.

Alex degnes ( 2t stuffing) and others lifted much more, and this caused overheating problems.

So it seems not only a question of getting rid pressure before transfer opening??

Think low Performance engine needs less area than a high Performance one!?

Experts 😉 your newest findings? Conclusions? Thaughts?? 😉

Thanks!

Wolfgang

[ApolloMotoMoto]

Alex degnes ( 2t stuffing) and others lifted much more, and this caused overheating problems.

See the above comment about the excess pressure at transfer port open using the transfer ducts as "temporary exhaust ports".

If you lift the bottom of the exhaust port (port floor) too high with insufficient blowdown STA, then you will be using the transfer ducts as temporary exhaust ports through a large portion of the rev range.

It does not surprise me at all that sending hot exhaust gases down the transfer ducts makes the engine hotter than it would be if you were not doing that.

[wobbly]

Flett , It all revolves around what you are trying to achieve , and the other side of the coin is the experience of others , in reality. so far.
Taking the dyno proven fact that Jan lifted the RSA port floor 3mm and it " worked " , I did the same on a test KZ cylinder.
Jan has stated that this mod would only work if the Blowdown was fully optimized, and in the TM this is close to reality , but not quite as no pin plugs are employed.
So , I dynoed it and it gained close to 1Hp in 50.
Is this even remotely relevant in your twin pipe test cylinder - I think not , due to its application.

Alex does so many other idiotic things , all at the same time, so anything gained from that source is suspect at best - as he has never even come close to replicating , let alone besting
perfectly normal 50cc race engines used in FreeTech on petrol.
BRC , did the full , up to the top of the transfers deal , and in that low power application it " worked".
But subsequently several top tuners have attempted to take their engine and " tune " it for a high power , wide range , mini sprint car application
and failed miserably.
This is also not helped by the tiny case they employed , but when simming the thing ,using a proven 1.3 case and a " normal " BDC port it made huge power with nothing unusual needed.

So - dont be like Alex and go off on unnecessary , unproven tangents - get completely lost , and have to circle back to reality at a later date.
Build really well , something boringly normal first.
You are far enough off the planet as it is with the twin port concept - get that proven as an advantage first - enough of a win to start with in anyone's book.

[Flettner]

Flett , I all revolves around what you are trying to achieve , and the other side of the coin is the experience of others , in reality. so far.
Taking the dyno proven fact that Jan lifted the RSA port floor 3mm and it " worked " , I did the same on a test KZ cylinder.
Jan has stated that this mod would only work if the Blowdown was fully optimized, and in the TM this is close to reality , but not quite as no pin plugs are employed.
So , I dynoed it and it gained close to 1Hp in 50.
Is this even remotely relevant in your twin pipe test cylinder - I think not , due to its application.

Alex does so many other idiotic things , all at the same time, so anything gained from that source is suspect at best - as he has never even come close to replicating , let alone besting
perfectly normal 50cc race engines used in FreeTech on petrol.
BRC , did the full , up to the top of the transfers deal , and in that low power application it " worked".
But subsequently several top tuners have attempted to take their engine and " tune " it for a high power , wide range , mini sprint car application
and failed miserably.
This is also not helped by the tiny case they employed , but when simming the thing ,using a proven 1.3 case and a " normal " BDC port it made huge power with nothing unusual needed.

So - dont be like Alex and go off on unnecessary , unproven tangents - get completely lost , and have to circle back to reality at a later date.
Build really well , something boringly normal first.
You are far enough off the planet as it is with the twin port concept - get that proven as an advantage first - enough of a win to start with in anyone's book.

I'm not into "normal" "boring" , you know that Wobbly. This twin port engine was supposed to be heading up to Robs for a dyno run just to see where we are at as of now but the last outing on the AG has broken my ankle, full cast from knee to toes. This situation has put a spanner in the works and now I'm relying on others to help me, Ill have to fit in with them, hopefully some time over Christmas new year. I guess the good thing is the bikes still running fine and apart from bent handlebars is ready to race. The water cooled, twin powervalve cylinder is away being Nikasiled now, as soon as its back Im going to fit it up, water pump, radiator, servo valve control but in such a way as to be able to go back to air cooled cylinder if needed. these cylinders are all still the 48 x 58 stroke and bore, new 54 x 54 cylinder is under construction, hence the questions on exhaust area below transfers. unfortunately I work on semi educated guess work, perhaps I will measure the exhaust blowdown area and send you that for you to calculate properly. I intend to fit this new cylinder up to a Sliding Gib disc valve bottom end, crank case water cooled ..... a semi serious attempt, for me.
I guess ultimately I should build up a three port (normal) cylinder as comparison, if I can be bothered.

[wobbly]

All im saying Neil is that you are already " guessing" with the transfer ports , and you have an unproven twin port setup , now you are talking of heading off down another tangent of the Exhaust floor.
If the thing does not come up to expectations - let alone exceed them , where do you look , are the transfers wrong , is the twin Exhaust an issue , is the Exhaust floor causing a problem.

At the moment you are already tearing out your hair with a mid range tuning problem.
Its thus way , way too hard to diagnose and try to correct anything, even with all these elements in isolation , let alone several on top of one another.
No criticism of you at all, I just believe you could be making yourself twice the amount of work needed, unnecessarily.

[Flettner]

All im saying Neil is that you are already " guessing" with the transfer ports , and you have an unproven twin port setup , now you are talking of heading off down another tangent of the Exhaust floor.
If the thing does not come up to expectations - let alone exceed them , where do you look , are the transfers wrong , is the twin Exhaust an issue , is the Exhaust floor causing a problem.

At the moment you are already tearing out your hair with a mid range tuning problem.
Its thus way , way too hard to diagnose and try to correct anything, even with all these elements in isolation , let alone several on top of one another.
No criticism of you at all, I just believe you could be making yourself twice the amount of work needed, unnecessarily.
Ok, what should I do then? Ive got to make some sort of decision on this exhaust system. The more educated the better, I guess educated assumptions.��

[wobbly]

No - assumptions - they are just errors waiting to be revealed.
I already told you , if you treat each Exhaust port as a single ( to BDC ), then make the exit of each, 90% of that ports chordal area x Cosine of the roof down angle.
No guessing , no assumptions , proven methodology.

[Wos]

Often in a Diskussion between diffrent levels its is a problem, what somebody is reaching for, was not clearly difined ?

Goal should be... come together dear friends !? 😉

Grüße Wolfgang

[Flettner]

No - assumptions - they are just errors waiting to be revealed.
I already told you , if you treat each Exhaust port as a single ( to BDC ), then make the exit of each, 90% of that ports chordal area x Cosine of the roof down angle.
No guessing , no assumptions , proven methodology.

There is no definition between above transfer open and below transfer open port area.

[wobbly]

The area above TPO is called Blowdown , that plus the area below TPO to BDC is the Total Effective Exhaust Area.

[Flettner]

The area above TPO is called Blowdown , that plus the area below TPO to BDC is the Total Effective Exhaust Area.

The more blowdown effective area you have, the less area under transfer open to keep a correct Total Effective Area in 'balance' ?

[wobbly]

Wrong - you are making the assumption that the Total Effective has a major influence on the end result.
It is absolutely the least effective metric of anything.
Blowdown and Transfer STA in balance , are the be all and end all of an effective porting layout.
Sure, it by default impacts the duct exit area if using the 75% area guideline , but it still works very effectively in all situations.
The absolute correct methodology is to measure the duct exit Mach, but this can only ever gain a few extra % in power when starting from the 75% area rule for a 3 or T port layout.

[Flettner]

Wrong - you are making the assumption that the Total Effective has a major influence on the end result.
It is absolutely the least effective metric of anything.
Blowdown and Transfer STA in balance , are the be all and end all of an effective porting layout.
Sure, it by default impacts the duct exit area if using the 75% area guideline , but it still works very effectively in all situations.
The absolute correct methodology is to measure the duct exit Mach, but this can only ever gain a few extra % in power when starting from the 75% area rule for a 3 or T port layout.

I have photos to try to explain what I'm thinking but for some reason I've ben shut out from posting photos??
Not sure if its my phone or this site? Anyway what I will do is carry on but use the single port, 90% calculation for each side as we discussed and see what happens I guess.
I don't mean to be a nuisance, it just happens :laugh:

[husaberg]

I have photos to try to explain what I'm thinking but for some reason I've ben shut out from posting photos??
Not sure if its my phone or this site? Anyway what I will do is carry on but use the single port, 90% calculation for each side as we discussed and see what happens I guess.
I don't mean to be a nuisance, it just happens :laugh:

Photos atm are hard to attach, I think there is some software issues, I have to click and hold button in for a few seconds then let go and that seems to help.
I thought it was me and I signed up to another forum the other day and its not my mouse of internet. Its KB.
355326355327

[F5 Dave]

Ie been having issues with photos too.

[rgvbaz]

Hi all,

I'm after the ring pin location on a single ring kx100 piston - I can't seem to find it anywhere.

The standard two ring pin positions are available at Grampions site: https://www.mitaka.co.uk/piston.php?id=40
And are at 11 and 19mm from the centre.
I've brought one of there pistons and the top ring (at 19mm) is close to the B port and ideally I'd like to widen that a little.

Failing that, if anyone know of a 52ish mm piston with a 14mm piston pin could you point me in that direction.


The reason is that my Kawasaki AR93 barrel has cracked at the bottom of the liner (thats really thin with the current 54.5mm bore size) so a new liner, slightly smaller piston dia giving more thickness to the bottom of the liner coupled with a 10mm longer rod I have found may help prevent cracking. And fingers crossed give a little more power.

Cheers

Dave

[aljaxon]

Hi all,

I'm after the ring pin location on a single ring kx100 piston - I can't seem to find it anywhere.

The standard two ring pin positions are available at Grampions site: https://www.mitaka.co.uk/piston.php?id=40
And are at 11 and 19mm from the centre.
I've brought one of there pistons and the top ring (at 19mm) is close to the B port and ideally I'd like to widen that a little.

Failing that, if anyone know of a 52ish mm piston with a 14mm piston pin could you point me in that direction.


The reason is that my Kawasaki AR93 barrel has cracked at the bottom of the liner (thats really thin with the current 54.5mm bore size) so a new liner, slightly smaller piston dia giving more thickness to the bottom of the liner coupled with a 10mm longer rod I have found may help prevent cracking. And fingers crossed give a little more power.

Cheers

Dave

ive had a few problems with pins being in the wrong place. im currently running one with the gap over the middle of a transfer on one project, forget which. im sure they can be moved to suit. i shy away from tasks like that thinking they have to be done by specialists but i bet its just a case of pillar drill a bit of heat and possibly some space age glue and lots of crossing your fingers and toes. is it cos the aluminium expands quicker and more than the steel so the pin never comes loose?
in theory.....

[aljaxon]

quick question, what is the most likely reason that changes to tailpipe/baffle cone outlet diameter are making a massive difference to power output in my project in engmod yet hardly any difference on my pals different slightly smaller cc project? from 17 to 15mm on mine it makes a huge difference. his are almost identical. only when he goes down to 12mm does it make a big difference and then he gets like a growth on the top of his curve. looks weird.

[Frits Overmars]

the aluminium expands quicker and more than the steel so the pin never comes loose?Think again....

[husaberg]

Hi all,

I'm after the ring pin location on a single ring kx100 piston - I can't seem to find it anywhere.

The standard two ring pin positions are available at Grampions site: https://www.mitaka.co.uk/piston.php?id=40
And are at 11 and 19mm from the centre.
I've brought one of there pistons and the top ring (at 19mm) is close to the B port and ideally I'd like to widen that a little.

Failing that, if anyone know of a 52ish mm piston with a 14mm piston pin could you point me in that direction.


The reason is that my Kawasaki AR93 barrel has cracked at the bottom of the liner (thats really thin with the current 54.5mm bore size) so a new liner, slightly smaller piston dia giving more thickness to the bottom of the liner coupled with a 10mm longer rod I have found may help prevent cracking. And fingers crossed give a little more power.

Cheers

Dave

The 100cc conversions for rm and cr and ktm are 14mm 52mm
strike does 52mm 14mm pin pistons for kt100's
http://www.strikeproducts.com.au/pistons.asp
http://www.strikeproducts.com.au/pricelist.asp

[aljaxon]

Think again....

this expansion thing has always messed with my head. lets say a small hole in some aluminium, as you heat it up the aluminium expands and so why doesnt it expand towards the hole making it smaller?

why does the aluminium expand away from the hole and not towards it. i mean it expands towards the outside. how does it know which way it can expand?

[wobbly]

Forgetting for the moment about expansion - ring pins are easy to do.
You use drills , and or drill blanks if you can buy them.
Many are 1.5mm so you buy one at 1.45 to drill the hole , and a 1.5 to cut off the pin needed.
I grind an " arrow" head on the pin, as this helps it to enter the hole , and the alloy closes in around the reverse sharp edge and helps to hold it in place.
Some pins are in the upper face of the groove, not on the groove centerline - so you push a piece of alloy into the groove and make a center pop, then drill the hole and remove the inserted piece.

[wobbly]

Re stinger size effects. Its all to do with the bmep, and thus the flow rate at peak power.
The simple way to get a handle on this is to set the Exhaust Transducer length at 1/2 the stinger nozzle , and look at the Mach number at peak power rpm.
It should be 0.8 Mach.
Higher and the stinger is too small , lower its too big - easy.

[Flettner]

So to get STA in 'balance' we need EngMod?

[JanBros]

or you can use my excell :
https://www.kiwibiker.co.nz/forums/showthread.php/187285-2-stroke-excel-for-ports-heads-and-pipes

since I can't change the first post , the most recent downloads are at the back op the topic on page 4

[wobbly]

I was just about to suggest JanBros spreadsheet - it works perfectly , and easily.
There are copies of it also in the Files section of 2 Stroke Research and Development on FB.
Dont go there for any other reason - its a shitfight mess of egoes and complete crap , showing birdshit Mig welded pipes and the age old " what does my sparkplug say ".

[Flettner]

I give up, tried to post pictures again but ..... computer says no. :(

[Flettner]

or you can use my excell :
https://www.kiwibiker.co.nz/forums/showthread.php/187285-2-stroke-excel-for-ports-heads-and-pipes

since I can't change the first post , the most recent downloads are at the back op the topic on page 4

Some shit going on, all I see is a blank page?
But thankyou anyway.

[husaberg]

Some shit going on, all I see is a blank page?
But thankyou anyway.
https://www.kiwibiker.co.nz/forums/showthread.php/187285-2-stroke-excel-for-ports-heads-and-pipes

[rgvbaz]

The 100cc conversions for rm and cr and ktm are 14mm 52mm
strike does 52mm 14mm pin pistons for kt100's
http://www.strikeproducts.com.au/pistons.asp
http://www.strikeproducts.com.au/pricelist.asp

Cool, cheers for that 👍

I've been having a look and the ktm piston looks like a good possibility.

https://www.juddracing.com/products/vertex-piston-kit-sx-tc-mc-105cc-bigbore.html

Cheers

Dave

[F5 Dave]

Engineering first. Tuning second.

[JanBros]

Some shit going on, all I see is a blank page?
But thankyou anyway.

as I sid above : latest downloads are at the back op the topic on page 4 as I can't change the openning post


https://www.kiwibiker.co.nz/forums/showthread.php/187285-2-stroke-excel-for-ports-heads-and-pipes/page4

[ApolloMotoMoto]

latest downloads

Heya JanBros!

I wanted to thank you for putting this excel together and for keeping it maintained.

It is a 'must have' tool for designing a portmap.

I have used it for the race-teams cylinders for the past 2 years and the whole team is routinely amazed how accurate the "predictions" are.

We have a basic Performance Trends Inertial Dyno that Performance Trends helped us spec out for our engines that will be used in the future to start validating the power targets, but the "peak torque RPM" from the spreadsheet has been DEAD NUTS on everytime.

We use 80/85cc dirtbike pipes for our engines (I am not really interested in a "custom" pipe until I can start designing them in EngMod) and we will take the OEM dyno sheet for a given pipe and use the peak torque RPM from that dyno sheet as the peak torque RPM "target" in the JanBros spreadsheet in order to create a "good portmap" for that pipe.

It has been working amazingly well in combination with tunable taipipe restrictors to tune the stinger nozzle diameter in for a given setup, essentially using the stinger nozzle size to "adjust" for the BMEP difference between the engine that particular dirtbike pipe was designed for VS the BMEP our engine is actually pumping into the pipe.

I dont think the results we are achieving would be even close to possible without the uderstanding of port "STA" and the philosophy around "balancing" the Blowdown STA to the Transfer STA.


Cheers to all involved, you know who you are!

[ApolloMotoMoto]

The calculator simply uses 75% of the total effective port area as a guide.
This always works and always makes alot more power and generally I found that the duct exit should be about the area of the main port alone.
This usually ends up around 75% of the total ( by taking away the extra area of tripple ports) needed for lots of blowdown - thus power.

It was never intended to be used with a single port only as I havnt tested that at all, apart from years ago on TD3s etc, and we always went bigger back then, not smaller.

Theory says that having a smaller duct volume changes the Helmholtz frequency ( higher ) , and reduces the amount of exhaust residuals able to be stored in that duct ( meaning more clean mixture sits close) , but im not sure this theory will apply to making more power with a single port.
Having said that, a 40mm pipe entry on an engine only making 30 Hp is way too big, so reducing the duct and or header area, or maybe both, will very likely work real well.

Did you model the nozzle as a short tapered section ( 30mm say) from the duct exit up to the header dia ( as the first section of the pipe) and this is made as an oval to round transition in the flange on T port and tripple port designs.

Be real interesting to see if the sim reflects reality on a dyno, in your single port scenario TeeZee.


---------------------------------------------------------------------------------------------------------------------


From doing hundreds of simulations and building more engines than I care to count, the best power is made by matching the header inlet area to the total Ex effective area, but reducing
the duct to around the 75% as mentioned.

But when you have a single Ex port, out at 72% or whatever, and lift it to the max at around 200+ duration, the power is ALWAYs limited by the blowdown STA available.
A simple trapezoid will never be able to match a T port for ultimate blowdown STA capability.
Thus having a limited power capability, we already have a matching small port and duct.
I have found in many cases that power will go up if the duct exit is made around 90% for things like a TZ350, that has a big port, but the bmep ,thus power, is fairly low.

As Frits has alluded to we should be matching the duct to the blowdown available, and this would give a much better approximation to the ideal duct exit needed.


---------------------------------------------------------------------------------------------------------------------


Determine the chordal area of the port at the bore face x Cosine of the roof down angle x 0.75/2 = area of each of the two duct exits.
This assumes a T or 3 port setup with shit tons of Blowdown STA.

For a race single port the multiplier is around 0.9 but for those low bmep engines the bulk gas flow is slow compared to a " hot " engine so in this instance I have been down to around 0.8x to get the exit up near 0.8 Mach.


While we are talking about the "Wobbly Duct" exhaust duct nozzle concept, especially in the context of "non-tripple/T port" designs; like Flettners example of the twin port/ twin duct...

I am in the process of assisting in the design of a cylinder, and I am currently working on applying this "Wobbly Duct" concepy to a LOW BMEP single exhaust port engine.

By LOW BMEP I am talking an 85-90cc engine with a transfer port layout matching the single speed/ direct dirve KA100 Kart cylinders, but with a single exhaust port at 70% width.

Low timing for broad single speed/ direct drive power curve.

Low BMEP target because we only "need" to make ~15hp @10,500 rpm peak power to be pretty dominant compared to what currently shows up to the paddock.

This translates to 8.5 - 9 BMEP at a peak torque RPM of 9,500 rpm in the JanBros spreadsheet.

Yep, thats LOW.

In the linked images (I cant seem to upload any images directly):

I have a picture of the CHORDAL dimensions of the exhaust port window with its resulting area. (axial and radial exit angles are both 0deg currently, so there is no cosine reduction to perform) Along with a circle that yields 80% of that area, and a circle that represents 100% of that area.

Also included is a 'rough draft' of the proposed exhaust duct as cast in the cylinder with bolt on exhaust flange/ spigot and the first section of the pipe that will mate to this spigot.
-"restriction point" is 1.5x the bore diameter from the exhaust port face/ cylinder edge. The "back to 100%" point is 2x the bore diameter from the exhaust port face.

Dimensions: https://ibb.co/qJwLrXP

Exhaust Duct Draft: https://ibb.co/n37JXsB


Questions:

-Am I doing this right?

-Is 80% at the restriction point a fair place to start given the BMEP target of the engine?

-Given this is a single exhaust port at 70% port width (shape matching the "FOS Ideal 70% Port Shape" document), should the port shape at the 80% restriction point still be an ovoid to "pull" better on the outside edges of the single port? I have it as a circle in the image below, but I have a feeling this "should" be an ovoid, perhaps not with the "ears" of an Aprilia RSA, but closer to the older Honda shapes?

[JanBros]

tnx for the nice words, but I just put the knowledge of other people who shared it for free here and on pitlane ( :clap:) together into one spreadsheet. Nothing of it is mine , and since it is not mine I simply couldn't ask money for it.

[husaberg]

Cool, cheers for that ��

I've been having a look and the ktm piston looks like a good possibility.

https://www.juddracing.com/products/vertex-piston-kit-sx-tc-mc-105cc-bigbore.html

Cheers

Dave
Strike are made for iron liners most KTM are made for coated.
Strike which is a family business based in AUS will make pistons with custom pined rings in any oversize not .25 of a mm if you use KTM you are stuck with 3 fitting pistons abc . Strike do hone to size pistons.
http://www.strikeproducts.com.au/pistons.asp
http://www.strikeproducts.com.au/pricelist.asp

piston dimenions KT100s
https://cdn.revolutionise.com.au/site/vbjljyavzy51kppz.pdf

<tbody>


or custom applications for AIDKA and Speedway racing applications
Custom options include:
High Ring
Rotated Anti Rotation Pin for reeds and rotaries
Dykes rings
Sizes are made to order
Rings to suit are dependant on application







http://www.strikeproducts.com.au/images/line_blue.gif


PSS001 - Piston KT100S Smooth Finish


Smooth piston skirt finish
To suit Yamaha KT100S and ARC SPEC100 for AKA racing applications
Size increments 0.05mm between Æ52.0 and Æ52.75 then 0.01 increments above Æ52.75mm
Ring to suit is p/n PRS001



These are aus pasos
S001 Piston KT100S Std $83.00
PS002 Piston KT100S >Ø53.00* $83.00
PS003 Piston KT100S >Ø53.75* $83.00
PS004 Piston KT100S Special** POA
PSS001 Piston KT100S Std Smooth $91.50
*Not legal for AKA sanctioned events
**Custom options: Indexed A/R Pin Location to any angle


PRS001 P/Ring KT100S Std $21.50
PRS002 P/Ring KT100S Big Bore 53.5, 55.25, 55.5 $36.00
C001 Circlips Ø14*Ø1.0 x 50 off $45.00


PB001 Pin Bearing Thompson $18.00
PP001 Piston Pin Ø14*Ø8.9*40.4 $7.50
PP002 Piston Pin Ø14*Ø10*40.5 (Light) 7.50


</tbody>

[wobbly]

Yep , an oval @ 80% sounds on the money to me.

[yatasaki]

Cool, cheers for that ��

I've been having a look and the ktm piston looks like a good possibility.

https://www.juddracing.com/products/vertex-piston-kit-sx-tc-mc-105cc-bigbore.html

Cheers

Dave
Bad experience with mitaka lately on my kr1s, piston pin on both cylinders made one millimeter play in 1500km. Pin wasn't worn out and it was smooth but aluminum ...

[Condyn]

Question for Frits Overmars or anyone else who knows what I am referring to.
Several years ago I recall reading a text written by Frits about finding the optimal ignition timing. If memory serves, he talked about adjusting the timing for each rpm before combining them to create the best curve. I cannot find this text anymore and I would like to read it again.

[JanBros]

I have it in german, any good for you ?

[Condyn]

I am solo lingual but I could try translating it, so yes I am interested. Thanks

[wobbly]

Anyone here in NZ got a M30 x 1.5 female puller I could use to yank off the flywheel of the EngMod competition KR150.
Only need it for the 30 seconds it takes - can send straight back.

[Wos]

Frits ignition curves paper you can download in german here

https://oil-club.de/wcf/index.php?attachment/23174-z-ndkurven-132-pdf/

But Frits?
Wasnt a Englisch version available somewhere?

Thanks!

Wolfgang

[Wos]

Frits Englisch Version 😉

https://www.zweitaktforum.de/wbb/attachment/32332-frits-overmars-adapted-to-english-making-an-advance-curve-pdf/

[Condyn]

Thanks for tracking that down!

[ken seeber]

Gedday all,

The theme of this post is to get rid of those old fashioned expansion chambers with a straight header, and add some incredibly bulky packaging and an unknown, but complex crank coupling and swap these for something that mightn’t offer any advantages at all. Are you ready?

OK, recently on Rimar Motors FB page, where he shared the design and mfg of his 587v2 engine (Incredibly good stuff. See https://www.facebook.com/rimarmotors) that utilizes 2 * KTM 300 cylinders, someone asked him could he do a 3 cyl version. His immediate response was to say no, because of the bulk of the exhausts.

This reminded me of a time, 100 years ago at Orbital Eng Co, we first started testing a 3 cyl Suzuki DT85 1.2 litre outboard engine. We had no useful idea for the exhaust (expansion chambers were not a consideration) and various systems were made with separate headers etc. all worked at some point, but overall useless. Then we just created a simple chamber or plenum close to the 3 exhaust port outlets (similar to all multi cylinder outboards) and immediately got a nice high and flat power curve. This then, with time for emissions reasons, was changed to accept a catalyst brick forming the back face of the plenum.

Obviously in such an arrangement with an inline crank, there is an asymmetry in terms of communication lengths between cylinders. Unacceptable to any OCD type.

So, let’s arrange 3 cylinders symmetrically abut a common axis, with the exh outlet face facing the axis, ie inwards. With some form of a common plenum connecting the 3 exhausts, this could lead upwards via a single header pipe.

355364

How it would fit anywhere? Fletto, where are you??? :rolleyes:

[F5 Dave]

Well that and a petrol tank for a 900 2 stroke would defeat the whole purpose.

The only 2 strokes I've been regularly riding recently are 300 enduros. On the dirt they have ample power in all the right places.

[Vannik]

Gedday all,

This reminded me of a time, 100 years ago at Orbital Eng Co, we first started testing a 3 cyl Suzuki DT85 1.2 litre outboard engine. We had no useful idea for the exhaust (expansion chambers were not a consideration) and various systems were made with separate headers etc. all worked at some point, but overall useless. Then we just created a simple chamber or plenum close to the 3 exhaust port outlets (similar to all multi cylinder outboards) and immediately got a nice high and flat power curve. This then, with time for emissions reasons, was changed to accept a catalyst brick forming the back face of the plenum.

Obviously in such an arrangement with an inline crank, there is an asymmetry in terms of communication lengths between cylinders. Unacceptable to any OCD type.



Ken, you are talking about the one long path vs the two short paths.

355365

[ken seeber]

[QUOTE=Vannik;1131232270]Ken, you are talking about the one long path vs the two short paths.

Yes Neels, that's exactly the arrangement. Whether "actual equal lengths" in this situation would make any difference is unknown to me. One guy (Bromlech?) over here, shortly after GT750s came out, made a 3 into 1 system. I have no idea if they were any better performance wise , they had very long primaries, but they sounded so sweet.


F5 Dave, we're not talking about chook chasers here....:scooter:

See you all next year...

[rgvbaz]

Strike are made for iron liners most KTM are made for coated.
Strike which is a family business based in AUS will make pistons with custom pined rings in any oversize not .25 of a mm if you use KTM you are stuck with 3 fitting pistons abc . Strike do hone to size pistons.
http://www.strikeproducts.com.au/pistons.asp
http://www.strikeproducts.com.au/pricelist.asp

piston dimenions KT100s
https://cdn.revolutionise.com.au/site/vbjljyavzy51kppz.pdf

<tbody>


or custom applications for AIDKA and Speedway racing applications
Custom options include:
High Ring
Rotated Anti Rotation Pin for reeds and rotaries
Dykes rings
Sizes are made to order
Rings to suit are dependant on application







http://www.strikeproducts.com.au/images/line_blue.gif


PSS001 - Piston KT100S Smooth Finish


Smooth piston skirt finish
To suit Yamaha KT100S and ARC SPEC100 for AKA racing applications
Size increments 0.05mm between Æ52.0 and Æ52.75 then 0.01 increments above Æ52.75mm
Ring to suit is p/n PRS001



These are aus pasos
S001 Piston KT100S Std $83.00
PS002 Piston KT100S >Ø53.00* $83.00
PS003 Piston KT100S >Ø53.75* $83.00
PS004 Piston KT100S Special** POA
PSS001 Piston KT100S Std Smooth $91.50
*Not legal for AKA sanctioned events
**Custom options: Indexed A/R Pin Location to any angle


PRS001 P/Ring KT100S Std $21.50
PRS002 P/Ring KT100S Big Bore 53.5, 55.25, 55.5 $36.00
C001 Circlips Ø14*Ø1.0 x 50 off $45.00


PB001 Pin Bearing Thompson $18.00
PP001 Piston Pin Ø14*Ø8.9*40.4 $7.50
PP002 Piston Pin Ø14*Ø10*40.5 (Light) 7.50


</tbody>

Cheers mate 😃

[Storbeck]

[QUOTE=Vannik;1131232270]Ken, you are talking about the one long path vs the two short paths.

Yes Neels, that's exactly the arrangement. Whether "actual equal lengths" in this situation would make any difference is unknown to me. One guy (Bromlech?) over here, shortly after GT750s came out, made a 3 into 1 system. I have no idea if they were any better performance wise , they had very long primaries, but they sounded so sweet.


F5 Dave, we're not talking about chook chasers here....:scooter:

See you all next year...

How about if you take your online three cylinder and tip the middle cylinder backwards until the exhaust port flanges of the tipped back middle cylinder and the outer two cylinders from roughly an equilateral triangle? That may allow the other cylinders to be moved in a bit of possibly allow them more room for transfer ports to loop out and around.

Maybe that leaves the "headers" still too long or gives problems with balance and firing order or some such. Could add a balance shaft and still be way more simple the previous arrangement.

[ken seeber]

[QUOTE=ken seeber;1131232286]

How about if you take your online three cylinder and tip the middle cylinder backwards until the exhaust port flanges of the tipped back middle cylinder and the outer two cylinders from roughly an equilateral triangle? That may allow the other cylinders to be moved in a bit of possibly allow them more room for transfer ports to loop out and around.

Maybe that leaves the "headers" still too long or gives problems with balance and firing order or some such. Could add a balance shaft and still be way more simple the previous arrangement.

Storebeck, thnx for the input. Did think along similar lines, but the primary passages would be quite different in length, similar to Neel's pic. So, without being totally pedantic about symmetry, one could rotate the outer cylinders (see A1 & A2) such that the exh axis was aimed to the central plane of cyl B, with "near" symmetry in terms of passage lengths and angles.

One would have to do a sweetheart deal with a piston mfgr to create blank full skirt pistons and then, say on a 3 axis, make the corresponding cut outs to match the transfers. Would also be issues with the piston pin bores.

355371

However, the main question remains: Would a single common & low volume plenum work with such very short primary lengths?

[husaberg]

Suff
Hi Ken can you do a speil the Special 52-53mm KT100S Strike pistons in custom sizes and finishes and pinning rings or special Windows for RGVbaz.

[Frits Overmars]

Would a single common & low volume plenum work with such very short primary lengths?Not really. That common plenum would act like a Honda ATAC volume. In the Honda system this volume is closed when it is not needed; in your situation it will always be open, weaking all pulses all the time.
What you'd need is some rotating device that couples an exhaust port that is just opening with an exhaust port that is about to close, while the third exhaust port is open to the atmosphere via a sucking (loud!) megaphone.

[136kg136ps]

The only benefit I saw on the GT750 3into1 chambers was reduced weight. It was still a pig.
As we also had RDs, we spent the bulk of our time working on them as proven modifications and parts existed.
When the watercooled RZs came out the RDs were relegated to errands.

[TZ350]

.

I am unable to upload any pictures. But I had an interesting bike on the DynoJet dyno today.

An AG100 farm bike. Single cylinder two stroke with twin expansion chambers that made 27 rear wheel hp at something like 11,000 rpm.

[husaberg]

.

I am unable to upload any pictures. But I had an interesting bike on the DynoJet dyno today.

An AG100 farm bike. Single cylinder two stroke with twin expansion chambers that made 27 rear wheel hp at something like 11,000 rpm.

10 carrots, it's not you Rob, its KB. or at least an interaction.
355401355402

Anyone else having issues please post here.
https://www.kiwibiker.co.nz/forums/showthread.php/190343-posting-images-or-actually-not-being-able-to-attach-them/page2

[Flettner]

I got pictures too but unable to post.
https://youtu.be/hM5CXFXnj1E?si=ezTHbzImA2nYL1gI

[ApolloMotoMoto]

https://youtu.be/hM5CXFXnj1E?si=ezTHbzImA2nYL1gI

Curious....

Do you mind sharing the ignition curve you are running?

[Flettner]

Curious....

Do you mind sharing the ignition curve you are running?

Not at all, if I could only post puctures.

[ApolloMotoMoto]

Not at all, if I could only post puctures.

This is a workaround I have been using;

Upload the image here: https://imgbb.com/

Then post the resulting link within your post, like this:

Race Bike: https://ibb.co/q5Rz6k6

Thats my little Single-Speed Direct Drive road racing creation.

[diesel pig]

Race Bike: https://ibb.co/q5Rz6k6

Thats my little Single-Speed Direct Drive road racing creation.

That is beautiful. well done.

[TZ350]

.
355403 Ok, I can re post pictures I have posted before.

https://ibb.co/PcYnsWH
hhttps://ibb.co/26Th9g2

And it looks like I can do the work around ApolloMotoMoto suggested. But you have to click on the link to see the image.


This is a workaround I have been using;
Upload the image here: https://imgbb.com/ Then post the resulting link within your post, like this:
Race Bike: https://ibb.co/q5Rz6k6 Thats my little Single-Speed Direct Drive road racing creation.

There is possibly a KiwiBiker work around too. https://www.kiwibiker.co.nz/forums/misc.php?do=bbcode#imgcode

[Grumph]

The shape of that curve plus AG100 handling should make for an exciting ride.

I'm assuming that's the pre-powervalve cylinder.

[lodgernz]

.

I am unable to upload any pictures. But I had an interesting bike on the DynoJet dyno today.

An AG100 farm bike. Single cylinder two stroke with twin expansion chambers that made 27 rear wheel hp at something like 11,000 rpm.

Is is still 100cc? Seems like an awful lot of HP.

[Flettner]

127cc, rubbish 48 x 58 , stroke and bore.

[Flettner]

The shape of that curve plus AG100 handling should make for an exciting ride.

I'm assuming that's the pre-powervalve cylinder.



Hence the broken foot.
Yes, still my orginal air cooled home cast none powervalve cylinder.
Water cooled powervalve one got held up at NZ Cylinders before Christmas, wont see it until after the 13th.

[Flettner]

Curious....

Do you mind sharing the ignition curve you are running?

No still no picture post ability lll take a wee video of it.

[Flettner]

Curious....

Do you mind sharing the ignition curve you are running?

https://youtu.be/8gfTSOqdQI8?si=nnXkEanjpG27JmFU

This what is in the AG at the moment.
To help with shaky picture / video, 2000 - 30 degrees
At 6500 starts reducing, 11000 at 12 degrees and reduced from there to 5 at 12500. We never got there.
At 11500 its 10 dgrees.

[ApolloMotoMoto]

...At 6500 starts reducing,

11000 at 12 degrees...

Okay, so I understand you have the powervalve cylinder comming, but...

I have asked Wayne Wright about what RPM you should start pulling timing when you DONT have a powervalve:

Here is what I remember him saying;

-With a powervalve you can get away with pulling timing where you are now, around 66% of peak torque.

You dont have the torque curve posted with the HP curve, but given the timing and the size of the engine, I am betting with peak HP at 11k, peak torque is really close to 10k.

10k rpm x 66% = 6,600 RPM.

So, you are currently pulling timing right around exactly 66% of peak torque, around the ideal point to pull timing when you DO have a powervalve.

-When you DONT have a powervale, you cant pull timing that early because there is no powervalve to help you through the torque dip AT 66%.

Looking at your chart, I would expiriment with pulling timing later and later than 6,500.

Pulling timing somewhere after 6,500, maybe even waiting till around 8,000 to pull the timing looks like it would do quite a bit to fill in that hole.

In order to keep the top-end of the curve where its at now I would slide in a couple more set points:

-15deg @10,000rpm
-12deg @11,000rpm
-10deg @11,500rpm
-5deg @12,500rpm


You can see the results of pulling timing at 6,500 right on your dyno graph.

Annotated Dyno Graph for reference: https://ibb.co/t8s73j1

-250 RPM's after you pull the timing at 6,500 the powercurve starts to crash at 6,750, and doesn't start recovering again until around 8,000.


Do you have the torque curve you can share?

[ApolloMotoMoto]

Image of Flettners Timing Curve: https://ibb.co/3vtFtjz

[Flettner]

Okay, so I understand you have the powervalve cylinder comming, but...

I have asked Wayne Wright about what RPM you should start pulling timing when you DONT have a powervalve:

Here is what I remember him saying;

-With a powervalve you can get away with pulling timing where you are now, around 66% of peak torque.

You dont have the torque curve posted with the HP curve, but given the timing and the size of the engine, I am betting with peak HP at 11k, peak torque is really close to 10k.

10k rpm x 66% = 6,600 RPM.

So, you are currently pulling timing right around exactly 66% of peak torque, around the ideal point to pull timing when you DO have a powervalve.

-When you DONT have a powervale, you cant pull timing that early because there is no powervalve to help you through the torque dip AT 66%.

Looking at your chart, I would expiriment with pulling timing later and later than 6,500.

Pulling timing somewhere after 6,500, maybe even waiting till around 8,000 to pull the timing looks like it would do quite a bit to fill in that hole.

In order to keep the top-end of the curve where its at now I would slide in a couple more set points:

-15deg @10,000rpm
-12deg @11,000rpm
-10deg @11,500rpm
-5deg @12,500rpm


You can see the results of pulling timing at 6,500 right on your dyno graph.

Annotated Dyno Graph for reference: https://ibb.co/t8s73j1

-250 RPM's after you pull the timing at 6,500 the powercurve starts to crash at 6,750, and doesn't start recovering again until around 8,000.


Do you have the torque curve you can share?

If I leave the timing at 30 degrees any later than 6500 I feel detonation. As it is now, nothing, clean.
Im not too concerned as the water cooled powervalve cylinder will be operational soon.
I'll test running a 20 degree reverse taper cone as well instead of this 17 degree one Im useing at the moment. And shorten them up a little as Id like to see 12,000, brobably just enough by the steeper taper. I'll measure it clearly.

[ApolloMotoMoto]

Reference Image of Aprilia RSA timing curve: https://ibb.co/VMkxZ0M

(Powervalve Engine)

Timing Pulled from the 30 degree initial starting at 8,000 rpm = 64% Peak Torque RPM (Peak Torque RPM = 12,517)

Timing at Peak Torque 12,517rpm = 16 degrees

Timing at Peak HP 13,000rpm = 14 degrees

Timing at Peak OverRev 14,000rpm = 9 degrees


....just for a reference example of a highly optimized powervalve ignition curve.

[Flettner]

Reference Image of Aprilia RSA timing curve: https://ibb.co/VMkxZ0M

(Powervalve Engine)

Timing Pulled from the 30 degree initial starting at 8,000 rpm = 64% Peak Torque RPM (Peak Torque RPM = 12,517)

Timing at Peak Torque 12,517rpm = 16 degrees

Timing at Peak HP 13,000rpm = 14 degrees

Timing at Peak OverRev 14,000rpm = 9 degrees


....just for a reference example of a highly optimized powervalve ignition curve.

If I continue with this cylinder I will be fitting a form of ATAC bottle.

[wobbly]

See Neil , there you go again. " I'd like to see 12,000 " sure go right ahead and shorten the pipes - correct move.
But what the hell are the ports doing at that rpm?
I dont want you to be like Fauchi and blindly " follow the science" , as his bullshit was made up, but STA science isnt.

There is already a completely obvious mismatch between the pipe geometry , and the port timing, as there are a hundred other engines with single port/pipe combinations that work perfectly well
without a PV and they dont have a huge torque " hole" like that graph shows.
Now you are planning another ,completely unplanned move, off on a weird arse tangent - are you gonna get lost, my money is on Alex achieving 10Hp on petrol in another 5 years.

[Wos]

Let us see the good things Flettner did 😉

He did a first dyno run ever!!! 👍 congratulations!

Good starting in the new year, maybe going from now step by step 😉 continuing with only one thing till you failed or better gained something...

Detos near to 6500 you eleminated are not a Garantie engine producing optimum there...maybe advance ist still to much...

Not sure that 30 advance on bottom is necessary 🤔 ...and maybe it could be better to go with a steeper/earlier falling advance after peak power ...for example 😉

A lot test work for decades...

Have a good one 😉

Wolfgang

[Flettner]

See Neil , there you go again. " I'd like to see 12,000 " sure go right ahead and shorten the pipes - correct move.
But what the hell are the ports doing at that rpm?
I dont want you to be like Fauchi and blindly " follow the science" , as his bullshit was made up, but STA science isnt.

There is already a completely obvious mismatch between the pipe geometry , and the port timing, as there are a hundred other engines with single port/pipe combinations that work perfectly well
without a PV and they dont have a huge torque " hole" like that graph shows.
Now you are planning another ,completely unplanned move, off on a weird arse tangent - are you gonna get lost, my money is on Alex achieving 10Hp on petrol in another 5 years.

Thanks for the encouragement :rolleyes: . Perhaps Ill re post if I accidently luck on something significant, apologies for posting my weird arse shit here.
I guess Ill have to invest in EngMod or borrow the use of someone's copy as this next 54 x 54 cylinder is on the pattern table now and I don't want to fuck that one up. :laugh:

[ApolloMotoMoto]

I guess Ill have to invest in EngMod or borrow the use of someone's copy

The JanBros 2.0 Excel Spreadsheet for Calculating Port STA is 100% free and 100% accurate for calulating port STA and the resulting peak torque RPM that STA will support.

You dont have -ANY- need for EngMod until you are trying to do power predictions for proposed changes, or you are actually interested in designing a real pipe.

If your ports peak torque RPM doesnt currently match the pipes peak resonance RPM, thats a problem you can solve FOR FREE with JanBros.

If your blowdown STA's peak torque RPM current doesnt match your Transfer STA's peak torque RPM, that is also a problem that you can solve FOR FREE with JanBros.

I honestly dont even know how you are choosing how large to make the transfer ports, or what timing to set them at without doing the calculations.

130 degrees of transfer timing is a LOT of transfer timing, and with 195 degrees of exhaust timing with your dual port (T port) exhaust, you really SHOULDN'T need 130 degrees of transfer timing to balance the blowdown you are pushing.

Not unless you have incredibly small transfer ports leaving a lot of cylinder bore on the table between the transfer ports....?

Excessive Transfer timing in a portmap will 100% make the 2/3 torque hole worse.

Enter your portmap into the JanBros Spreadsheet and it will become pretty clear what needs to happen.


You really dont need to appologize, Wobbly's just a cantancerous old fart.

And, to be fair, he already told you exactly what you ought to do.

This isnt the first time the FREE JanBros Spreadsheet has been recommended to you for STA calculations.


:wink:

[Flettner]

The JanBros 2.0 Excel Spreadsheet for Calculating Port STA is 100% free and 100% accurate for calulating port STA and the resulting peak torque RPM that STA will support.

You dont have -ANY- need for EngMod until you are trying to do power predictions for proposed changes, or you are actually interested in designing a real pipe.

If your ports peak torque RPM doesnt currently match the pipes peak resonance RPM, thats a problem you can solve FOR FREE with JanBros.

If your blowdown STA's peak torque RPM current doesnt match your Transfer STA's peak torque RPM, that is also a problem that you can solve FOR FREE with JanBros.

I honestly dont even know how you are choosing how large to make the transfer ports, or what timing to set them at without doing the calculations.

130 degrees of transfer timing is a LOT of transfer timing, and with 195 degrees of exhaust timing with your dual port (T port) exhaust, you really SHOULDN'T need 130 degrees of transfer timing to balance the blowdown you are pushing.

Not unless you have incredibly small transfer ports leaving a lot of cylinder bore on the table between the transfer ports....?

Excessive Transfer timing in a portmap will 100% make the 2/3 torque hole worse.

Enter your portmap into the JanBros Spreadsheet and it will become pretty clear what needs to happen.


You really dont need to appologize, Wobbly's just a cantancerous old fart.

And, to be fair, he already told you exactly what you ought to do.

This isnt the first time the FREE JanBros Spreadsheet has been recommended to you for STA calculations.


:wink:

Im a cantankerous old fart too. Last time I tried to use the free spread sheet I kept getting a blank page. Im sick of fighting with computers, so I abandoned the idea.
Perhaps, Ill try again when Im in a better frame of mind. Thankyou for your input :niceone:

[ApolloMotoMoto]

Im a cantankerous old fart too. Last time I tried to use the free spread sheet I kept getting a blank page. Im sick of fighting with computers, so I abandoned the idea.
Perhaps, Ill try again when Im in a better frame of mind. Thankyou for your input :niceone:


I will say, if you have ZERO experience using Microsoft Excel, then there will be a bit of a learning curve.

If you have any friends who work in finance, or perhaps even a wife with excel experience; having someone who is an excel pro stand over your shoulder to get you up and running would be a huge benefit.

I had started with zero excel experience, and it took a bit of googling to get me sorted.

Once you get through the initial learning curve, everything in the JanBros spreadsheet is 100% automated, you input your data in the data fields, and it does the rest.

[wobbly]

Absolutely NOT denigrating your work Neil, as what you are doing is valuable, genuine , R&D.
But as so often happens with the individuals who are actually very capable of doing this work, they get so tied up in the process that they flail about like a mad womans shit
from one tangent to another without paying attention to the very basic design detail.

You have a big issue with a port/pipe mismatch creating a huge torque hole, that is not going to go away , and a new PV is a bandaid "fix" , not actually addressing the base issue.
Shortening the pipes is NOT going to help this problem , if the ports are already wrong , and may never in fact be capable of supporting 12,000 rpm.

I am really , really pushing you to get on top of JanBros spreadsheet as the kind of info it will give you far outweighs the frustration you feel even trying to get it installed.
If you simply cant even download it , its available in many places , but executable programs are blocked by most email servers, maybe someone here has it on a cloud based storage medium
and can give you a link.

[Wos]

Flett...think you made progress last days in your ligue...before you told us max reves you saw were about 11500...now 12000...!? 😉 think...well done!!

Dont mind about the talking, the advices for other levels...as long as you do so much progress....you need no further digital calculators that promise you heaven 😉
Often the better way in our ligue is to keep it simple...

[ApolloMotoMoto]

Here is a JanBros 2.0 download link on Facebook:

https://www.facebook.com/download/6848931668551911/JanBros2-stroke2.0.xlsm?av=100011766914938&eav=AfYPETEEJ1p7nHXep1zP1IEQBi063VBDp-0-ZJWtQsq2tjDiZyDl9bEcCKte-Ic_EDI&paipv=0&hash=AcpJQXCMm2ou7Cb9pmU&__cft__[0]=AZVzRw28jPKLyZnr7owCKjHihqJEQiDUh5TL7haxGVCPsx9mp ywnkeYnpCEU8nJTnLAOYnL3DlXuARCJKfyD16XMXsJLoSorFrq ooBEG5s1XGe2RJwWb8n6HVd1BmVeNBh7dEUfsX9w8Gzc_ma3NY N2Tz5xJus14qxb4B04gbvpEhQ&__tn__=H-R



This is the most recent download link from JanBros (2.2) here on KiwiBiker (Dropbox link):

Excel File:

https://dl.dropboxusercontent.com/scl/fi/kkrtwe77k1k0l29ue6m1c/JanBros-2-stroke-2.2.xlsm?rlkey=xoauprgm0rhwklrr24mkbi7gq&st=g69206c6&dl=0

Word File INSTRUCTIONS:

https://dl.dropboxusercontent.com/scl/fi/1nd418esc40e76r8xrcbc/JanBros-2-stroke-1.2.docx?rlkey=cy9a7q74h74oy48633s5yj8e1&st=8dmk16js&dl=0

[Flettner]

Ill have to get someone to install it for me and show me how to run it... I guess, thankyou.
In the mean time an inertia dyno would be very useful, I learnt a lot in a very short time at Robs ESE dyno on new years day, invaluable.
For now I just wait for the water cooled cylinder to get back from NZ Cylinders, still a 58 x 48 bore and stroke. The max safe stroke I can have with the AG crankcase, unfortunately.
I'm drawing up new cases to get the 54 stroke required for the cylinder on my pattern bench, also will have disc valve / sliding Gibb and a six speed close ratio gearbox. At the moment the AG only 4 speed, usable.

[ApolloMotoMoto]

Ill have to get someone to install it for me and show me how to run it...

Here is a question:


Do you have Microsoft Excel installed on your computer?

I think most people just kind of assume every computer in the world has the full Microsoft Office Suite....

If you dont have Excel installed on the computer that would make your resulting "blank page" make a lot more sense.

[Flettner]

Here is a question:


Do you have Microsoft Excel installed on your computer?

I think most people just kind of assume every computer in the world has the full Microsoft Office Suite....

If you dont have Excel installed on the computer that would make your resulting "blank page" make a lot more sense.

I'm on my computer now, behold, we have some action, I can see the page, thankyou. Ill have a bit of a play with the inputs and see what happens. Too easy. :cool:

Ill be back with questions (many) I'm sure. I appreciate you perseverance.

for example, what's old and new about?

[JanBros]

Flett, if you take about 10mins to read the doc, almost everything should be clear.

Everything "old" is where you enter all the data "as your engine is right now". after you have done that, you never change anything in "old" afterwards. All changes are done on the "new" pages.
On new you can start from scratch making new port's (to do this, delete everything in the green cell's on new) , or copy alle the green cell's (on all pages) from "old" to "new" and make changes. on some pages, there are lighter and darker green cell's, it is all explained in the doc.

for the macro's to work (macro's are some sort of code to perfrom an action like behind the purple push buttons autoadjustgraph, your exell-file needs to be saved first in a trusted environment (think it's called like that in english), you'll find it somewhere under
file -> options -> trust environment -> settings for trust ... -> trusted locations , and there you can create a new trusted location, or find out where the standard one is and store it in there

edit : you could also forget all the "new" and make the changes in old if for example you only want to change the size and timing of the port's, but than you lose your refference as to how it was and what changes you've made. before making changes, save it under another name so you can always go back to the original

[ApolloMotoMoto]

Flett, if you take about 10mins to read the doc, almost everything should be clear.

Thanks for jumping in JanBros!

I will 100% commit to help Flett work through any stumbling blocks he finds himself in beyond the instructions :D

There are few little things that can throw you through a loop until you understand how the spreadsheet it doing things.

Its crazy how much it can actually do given the limitations, and once you understand how it flows, I find it incredibly intuitive.

[136kg136ps]

https://www.libreoffice.org/

https://www.openoffice.org/product/calc.html

Two alternatives to Excel that are free and have several other programs that may come in handy.
I haven't tried browser borne or web based AI for anything complex yet but that is a possibility. A certainty in the near futrure.

[jonny quest]

Wobbly, it is kind of a d*ck move condemning Flettners journey.

What your failing to realize is there is always good from failure and success.

Flettner has a project he wanted to accomplish, he has the genius to carry it out. Kudos to that.

Even if it will never be a world class GP engine... it has my interest along with many others.

Not everything can be accomplished with a sim either, a sims output is derived from known good data, and bad.

If we all followed the same template, nothing new would be discovered.

[Flettner]

Wobbly and I are well acquainted, Ive build many things for him in the past, yes he can be a prickly old bugger, but so can I:msn-wink:.
I guess I should not have 'bitten', but I did. Ill keep my pricklyness to myself, I most certainly dont want to cause any issues here .... I very much appreciate this forum and all those posting. Unlike other forums this one seems to be for the serious tuners / tinkerers, not 'how does my sparkplug look' or 'rate my piston wash' gang :laugh:
Lets keep things convivial yet to the point at this 'dinner table'. :niceone:

[wobbly]

The whole point of my initial post , and the subsequent explanation of why I said what I did , was simple.
I have seen it over and over again, clever people " trying new stuff " when what they are starting out with is already flawed and needs that ,or several issues, to be fixed before even thinking of
going off on another tangent.
All this process does is waste a heap of valuable R&D time.

Neil has a huge torque hole in the lower powerband , that issue needs to be addressed BEFORE even suggesting shortening the pipes , that will only make things worse down there.
Not solving anything , but more likely , making it even harder to trouble shoot the real problem.
If we were over dinner , I would say exactly that, and accuse him of several forms of self abuse while I was at it.
I was helping by pointing out the reality of the situation ie being truthful, to not do so in my opinion is way worse than saying nothing.

Thousands of people have been using things like EngMod or JanBros excel to produce optimized engine parameters for decades now, thru all this Neil has been very , very cleverly actually making
things - but its well past time to stop guessing.
Why , because its now really easy for him to do it properly.

[F5 Dave]

I think I'll just pop in to explain to overseas members how the kiwi bloke interaction can be what appears brutal towards people we know and like.

Some of that banter was more obvious when there were more racers on the other threads trading insults like rubbed paint on the track. But none of it is serious, quite the opposite.

Problem is, that backstory of who knows who and facial expressions is lost on the Internet.

Short story, it's all good mate.

[Flettner]

The whole point of my initial post , and the subsequent explanation of why I said what I did , was simple.
I have seen it over and over again, clever people " trying new stuff " when what they are starting out with is already flawed and needs that ,or several issues, to be fixed before even thinking of
going off on another tangent.
All this process does is waste a heap of valuable R&D time.

Neil has a huge torque hole in the lower powerband , that issue needs to be addressed BEFORE even suggesting shortening the pipes , that will only make things worse down there.
Not solving anything , but more likely , making it even harder to trouble shoot the real problem.
If we were over dinner , I would say exactly that, and accuse him of several forms of self abuse while I was at it.
I was helping by pointing out the reality of the situation ie being truthful, to not do so in my opinion is way worse than saying nothing.

Thousands of people have been using things like EngMod or JanBros excel to produce optimized engine parameters for decades now, thru all this Neil has been very , very cleverly actually making
things - but its well past time to stop guessing.
Why , because its now really easy for him to do it properly.

Ok, that said, point me in the right direction, thankyou. What would you change if you were forced to do this project, being that there are some ''obvious'' shortcomings.... but you are not allowed to go back to a single pipe or three port configuration. :shifty:
Also understand this configuration was always destined to run with a powervalve. This first version was just a lets ''see what happens'' with twin pipes, after all some said it would hardly run with two separate pipes. (Luc).
Furthermore originally I was just keen to see if I could actually cast an air cooled cylinder having never cast one before, thought it might be nice to combine and cast twin port as well as I wanted one to experiment with. Remember this one is largely just a copy of Jawa back in the day. Things will get more interesting IMO when this next cylinder is operational, first water cooled (one of the big problems with original TP Jawa, heat soak) and powervalves, also I believe a necessity for successful TP. Although this cylinder is still a rubbish at 58 x 48, the real attempt 54 x 54 is just wood and bondifil at the moment. 54 x 54 will be running the Sliding Gibb disc valve (something that was also rubbished when I first started working with the concept) and ultimately cast to accept Quad TPI at a later date. I might remind you KTM have dined out on my (and Wayne Blackwood ) original TPI for years.
I was also told that was a waste of time when we were developing it.

Besides, what is a ''waste of time''? I've had two successful and fun Vinduro seasons on the AG with this cylinder, astoundingly reliable for something I've built, although I'm not a skilled enough rider to win the series the AG will take on all contenders in the open stuff, no contest.

A note on the ''hunting'' issue, only seems to happen when hot and also doesn't happen if the throttle is just held open, both conditions will disappear with the new PV cylinder I believe. :niceone:

[wobbly]

Absolutely first thing to do is an STA analysis of the Blowdown Vs the Transfers.
This will highlight immediately any shortcomings in that area of design.
Second thing is if " it goes away when cold " has got to mean that there is a mismatch between the needle/tube annulus and the main jet.
Its seen especially well on the dyno, low rpm/WOT fueling is set by the needle tip/emulsion tube annulus area.
And if this is too rich ie the needle tip is too small , then as you wind in the throttle toward WOT , it will be getting richer and richer.
Not so evident when cold, as a rich mixture is OK in that circumstance.
Then further up the rpm scale as the main takes over mixture control it may in fact be perfectly OK - as is evidenced by the dyno curve.

All I am saying is get this shit sorted first , before heading of into left field and shortening the pipes.

And with reference to your mates at KTM - looks like what goes around comes around , they are on the verge of bankruptcy , and cant afford to pay Danny Pedrosa
his E 600K let alone give you anything concrete in return.

[Flettner]

Probably as evidenced by the clip needing to be on the top groove already, fucking carburetors, trying to find carburetor stuff these days can be difficult. I used to deal with Sudco but they are no more I hear. Google I guess, somewhere there used to be a Mikuni needle chart.... found it, best find out what I've got first.

[ApolloMotoMoto]

...trying to find carburetor stuff these days can be difficult. I used to deal with Sudco but they are no more I hear.

Jets-R-Us has been my go-to for a while.

[F5 Dave]

Do the rules allow you to jetison the Mikuni? A PWK28mm is a fine dirt carb as on KX85 etc and will be easier to jet / have better throttle response. Can easily handle 35hp on an RZ350. I avoid the Chinese copies.

[ApolloMotoMoto]

Do the rules allow you to jetison the Mikuni? A PWK28mm is a fine dirt carb as on KX85 etc and will be easier to jet / have better throttle response. Can easily handle 35hp on an RZ350. I avoid the Chinese copies.

I will second the recommendation to ditch the Mikuni for a Keihin PWK if the rules allow for it.

[Flettner]

I will second the recommendation to ditch the Mikuni for a Keihin PWK if the rules allow for it.

No problem with rules, just cost. The Mikuni was free and appears to be about the right size at 34mm.
In fact there is no rule against FI, but that would introduce unreasonable cost at this point.
This is one of four (two stroke) carburetors that came off a Subaru 1800cc engine powering an Autogyro, flown many hours in England then around most of NZ. I collected them out of a bin as the craft was re fitted with a LINK EFI, waste not want not. All jets appear standard accept the needle, I ordered a new needle from Sudco, what the carburetor would have been sold with in the first place, a 5FP17. Figured Id at least be in the ballpark.

The aircraft needle was a 6FJ40, not the right needle for a 34mm I think?

[F5 Dave]

KX125 has a PWK35 . Big carb for a 100cc dirtbike used for Enduro I would have thought. I had one surplus but I sent it to another chap casting an engine as a mock up.

My spare 28 was lent to a bucket racer, but i haven't seen him for 15 years so safe to say I might not be getting that one back.:laugh:

[Flettner]

125cc Dave, but thankyou anyway.

[ApolloMotoMoto]

This is one of four (two stroke) carburetors that came off a Subaru 1800cc engine powering an Autogyro, flown many hours in England then around most of NZ. I collected them out of a bin as the craft was re fitted with a LINK EFI, waste not want not. All jets appear standard accept the needle, I ordered a new needle from Sudco, what the carburetor would have been sold with in the first place, a 5FP17. Figured Id at least be in the ballpark.

The aircraft needle was a 6FJ40, not the right needle for a 34mm I think?

Playing with fire all over the place aren't we?

So, what makes you think this Autogyro carb runs the same emulsion tube as the MX setup would?

Same question for the Needle Jet ;)

So, you have the potentially appropriate Jet NEEDLE for that carb on an MX bike...

Idle Jets and Main Jets are fairly simple to sort out;

What about the air corrector, does it have a removable/tunable air corrector "jet" accessable inside the bell mouth?
(not talking about the screw-adjustable corrector; I am talking about a removable and tunable 'jet' that feeds that emulsion tube with the air it will use to emulsify the rising fuel...)

The Needle JET (the orrifice right at the base of the carb throat, right were the needle first ...penetrates....) has a 2-stroke shroud on it, sure, but is that shroud height ideal for MX riding?

Is the Needle Jet ORRIFICE SIZE the proper corresponding diameter to match that 5FP17 needle?

Is the emulsion tube you are threading main jets into the correct emulsion tube for MX riding at ...ground level.... ?


Interesting questions those....

[ApolloMotoMoto]

For reference;

This is the Needle JET: https://ibb.co/mH0pY0N

[wobbly]

Once you have figured out what you have and consulted the chart - I have just ordered a manifold from MikuniOZ.com
Plenty of stock , reasonable pricing for parts and freight.
You dont have an issue with the Air Corrector or the shroud height ( yet ), as they adjust the fuel curve with increasing rpm - nothing to do with going rich at low rpm/WOT

[Flettner]

Playing with fire all over the place aren't we?

So, what makes you think this Autogyro carb runs the same emulsion tube as the MX setup would?

Same question for the Needle Jet ;)

So, you have the potentially appropriate Jet NEEDLE for that carb on an MX bike...

Idle Jets and Main Jets are fairly simple to sort out;

What about the air corrector, does it have a removable/tunable air corrector "jet" accessable inside the bell mouth?
(not talking about the screw-adjustable corrector; I am talking about a removable and tunable 'jet' that feeds that emulsion tube with the air it will use to emulsify the rising fuel...)

The Needle JET (the orrifice right at the base of the carb throat, right were the needle first ...penetrates....) has a 2-stroke shroud on it, sure, but is that shroud height ideal for MX riding?

Is the Needle Jet ORRIFICE SIZE the proper corresponding diameter to match that 5FP17 needle?

Is the emulsion tube you are threading main jets into the correct emulsion tube for MX riding at ...ground level.... ?


Interesting questions those....

It is a standard flat slide Mikuni 34mm twostroke carburetor. It was adjusted by the original original owner, from new, to run on a fourstroke although Its not a fourstroke carburetor, emulsion tube is still what came standard with the carburetor when originaly sold ..... as a twostroke carburetor, all that was changed was the needle and main jet to run on the gyro. also the float valve but that's been changed back to a low pressure unit.

[Flettner]

Once you have figured out what you have and consulted the chart - I have just ordered a manifold from MikuniOZ.com
Plenty of stock , reasonable pricing for parts and freight.
You dont have an issue with the Air Corrector or the shroud height ( yet ), as they adjust the fuel curve with increasing rpm - nothing to do with going rich at low rpm/WOT

A 5FP17 is whats in it now.

[wobbly]

Well that , right there is the major difference between a 4T and a 2T.
The 4 stroke needs a heap of fuel as you wind on the throttle - explicitly why they have ,in most cases, an accelerator pump.
A 2T does not need or want the extra fueling at all.

[Flettner]

Well that , right there is the major difference between a 4T and a 2T.
The 4 stroke needs a heap of fuel as you wind on the throttle - explicitly why they have ,in most cases, an accelerator pump.
A 2T does not need or want the extra fueling at all.

No that's what I put in it, it had a 6FJ40 in it when it was in the aircraft.
Sudco told me they are sold standard (for twostrokes) with a 5FP17 needle, so I bought four of them (I've got four carburetors), that's what I've been running. I've never run it with the 6FJ40. The 6FJ40 is a much fatter needle. Perhaps I should try it? When I can ride again.

[husaberg]

Spankme seems to have fixed the attaching files and photos.

For Neil an explanation of the 4t vs 2r needle jet ie emulsion tube.
355422355423355424355425

355426
this too

https://www.kiwibiker.co.nz/forums/album.php?albumid=4844&attachmentid=301846
https://www.kiwibiker.co.nz/forums/album.php?albumid=4844&attachmentid=301846
https://www.kiwibiker.co.nz/forums/album.php?albumid=4844&attachmentid=301846
https://www.kiwibiker.co.nz/forums/album.php?albumid=4844&attachmentid=301845
https://www.kiwibiker.co.nz/forums/album.php?albumid=4844&attachmentid=301762
https://www.kiwibiker.co.nz/forums/album.php?albumid=4844

[Flettner]

I managed to post a test picture.

[TZ350]

.
Just testing to see if I can post pictures again.

355440

Yaeee Looks like I am back in business too. That is a picture of the turbo that is going on my 70cc EFI 2stroke project.

The aluminium housing for the hot end is something Speedpro helped me with to tighten up the AR ratio. Hopefully it will work better with my smaller engine.

[jonny quest]

Flettner, you can jet a carburetor pretty close on the stand.

What does it do when you hold throttle just above idle? Does it race up in rpm? If yes, your pilot and needle root are good.

What about 1/8 and 1/4?

Just listen carefully, does it blubber and then race up?

You'll get bad dips on dyno if it has to accelerate through these rich conditions.... even though you are testing wfo... it has to go through these rich conditions which causes false main jet readings.

[husaberg]

Flettner, you can jet a carburetor pretty close on the stand.

What does it do when you hold throttle just above idle? Does it race up in rpm? If yes, your pilot and needle root are good.

What about 1/8 and 1/4?

Just listen carefully, does it blubber and then race up?

You'll get bad dips on dyno if it has to accelerate through these rich conditions.... even though you are testing wfo... it has to go through these rich conditions which causes false main jet readings.


Hi have a look at page one of the thread.

https://www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner

[F5 Dave]

Geez, welcome back to 2008. Thought I knew something for a page or two.

[Frits Overmars]

This is Thomas a Vietnamese race mechanic.... he starts with a main jet so big the bike floods at about half throttle (apparently this proves the oriface of the needle/needle jet combo is big enough) and then he slowly step by step works back until it runs clean.That's the way. Most people think it's safe to jet up a bit and see what happens.
Here's what can happen. An engine runs so lean that it does not produce any power or heat.
Now you jet up, so it will produce more power and more heat, while still running too lean for its own health. That's not always fatal, but it can be.
If you jet up, start with a big step and then work back carefully, like Thomas did.

[wobbly]

I first tried the " so rich it wont run " thing about 10 years ago , by taking out the main jet completely.
Well in fact I had forgotten to replace it , being in a rush in the pits.
In that instance the thing would rev up perfectly to about 12,000 at WOT then fell flat on its face.
Made it very obvious the needle end / emulsion tube annulus was way too small.
So that got changed and I started rejetting the main.

That very same day was the first time I had used a fast response EGT gauge to assist with tuning.
It was also the first day I discovered that when the EGT flat lines , its not rich , its starting to deto and is lean AF.
As I then jetted down 1 size and it seized - destroying a brand new engine.
That lesson was so traumatic it has never left me - so if I say , quit guessing as well on this subject, and use data to inform your tuning choices , it has nothing to do with being a prickly bugger
its very hard won experience talking.

Here is the best value fast probe and gauge on the market - https://www.exhaustgas.com/ProductDetail.asp?ProductID=1482&DepartmentID=1&CategoryID=71&BasketID=

[ApolloMotoMoto]

A lot of interesting discussion on the topic of Correction Factors (differnt places, but it floats around).

And within those discussion was obviouslly some detailing of the in-and-outs of running a 2-stroke dyno cell...

Well, me and the team are currently getting our new PerformanceTrends dyno settled in its new home...

(and honestly pretty close to ditching the PerformanceTrends datalogger for a SportsDevices unit, once the initial setup is complete, and we confirm everything works as its supposed to, we are changing over to SportsDevices DAQ and software for access to 'Frits FOS 2-Stroke Correction Factor)

...and I have been reviewing a lot of screenshots I have taken from Frits and Wayne....

I believe I have come to the conlusion that neither of you use a Lambda/O2 sensor at all.
-I have read Frits paper on the confounding results one will get if they use "standard" AFR tuning methodology on a 2-stroke engine using a standard O2 sensor, and I am pretty sure I understand it.


So, my first question is;

A: Do you have -any- use for a Lambda/O2 sensor for running an engine on the dyno, or for tuning a carburetor "on location" at the track?

And my next question is;

B: If not, what is your procedure for establishing a proper "baseline" jetting in the carburetor, from which you will adjust to new conditions using RAD and EGT?


I believe I have gathered that, when starting from a known good baseline for the jetting in the carb for a specific RAD, and having a known good baseline EGT for the pipe, the procedure looks like this:

Baseline Carb Setting + Baseline EGT + Baseline RAD is written in stone somewhere useful and handy.

You arrive at some new location.

First thing first, what is the current RAD at the new location?

Next up, what is the difference between current RAD and the Baseline RAD?

Before you even run the engine, the jetting in the carb is adjusted a set amount given the difference in RAD.

To make a very simple example; if RAD is 5 points lower than baseline, the jetting is made 5 steps leaner.
(I have seen the graphed curve plot posted by Wayne a few times for making this determination...)

Now, with jetting adjusted as a factor of the difference in RAD, the engine is run up to temp, and pulled under load long enough to take an EGT reading from the pipe.

Does the CURRENT EGT match the Baseline EGT?

If no, fine-tune jetting until you achieve the Baseline EGT in the new current RAD conditions.

If yes, then hooray, you are ready to go racing if you are at the track....

If you are starting a new day of dyno testing, that means its time to make a baseline pass with your baseline setup.

Now you have a baseline run on a brand new day of testing, with different RAD from your previous baseline.

Apply your preferred correction factor to the new days baseline run and compare this CORRECTED curve to your previous baselines CORRECTED curve.

Do the baseline curves match -exactly- for the two different RAD conditions?

If no, your correction factor sucks ass, and you will have the pleasure of re-performing the baseline run everytime RAD changes if you want to accurately measure the difference between the new parts or ideas you area trying to test.

If yes, then hooray, your correction factor can be trusted to accurately compensate for changes in RAD as you perform A-B testing.


Last Question:

C: Do I have that right?

[wobbly]

Answer to the first question is no - Lambda I have available as an input on my SportDevices , but its only useful for determining A/F ratios at part throttle or transient conditions
with a completely new carb/engine setup.
To do this reliably the sensor should be right at the front of the muffler , screwed into a bung fitted to the body, that fits surrounding the perforated within the muffler.
But here is the kicker - Lambda tells you absolutely nothing about the limiting factor in 2T tuning - the onset of deto.
Only a fast response EGT probe and data log can give you this.

Thus on the dyno it is easy to review the EGT traces as you jet down - and each jet will increase the EGT by a quite accurate set amount.
When you go down a jet and the EGT does not increase - this is deto, go back one and that is your best power EGT at a specific RAD ( I use Density Altitude as the scale is bigger and the changes easier to plot ).
This is one data point on your jetting chart - but you must be sure that your test run time and water temps match what is seen on track.
So from now on , be it on the dyno , or at the track , you have a target EGT.

With different weather on a different day you can initially run rich and jet down to that specific EGT - now you have two data points linking RAD and jet size, determined by EGT for best power.
This is the graph I have published several times for KZ engines with differing tune and fuels, and thus EGT.
Looking at the red line on the graph , 5 points of RAD , say 95 to 100 , in this case gives an 8 jet split.
I have a full set of pinned jets and thus can change jetting in 0.01mm increments , but a normal jet set would only have 4 - in this case 140,142,145, 148 for a Dellorto.
You can also see on that line several other data points I have added to ensure accuracy for any setting with that engine and with that fuel.

Then yes , as you say , if you apply the above logic and rejet to a specific EGT , on different days , and your correction gives overlaying curves , then no arse sucking is involved.
The accuracy of the correction is determined by the Density Altitude number , thus I have used the 3 way calibration available for the SportDevices weather station , so it matches exactly the local airport numbers I can
get anytime on my phone - ensuring that no matter where I am the data I am using is from super accurate airport stations , as planes are not allowed to fall out of the sky.

[ApolloMotoMoto]

Thus on the dyno it is easy to review the EGT traces as you jet down - and each jet will increase the EGT by a quite accurate set amount.
When you go down a jet and the EGT does not increase - this is deto, go back one and that is your best power EGT at a specific RAD ( I use Density Altitude as the scale is bigger and the changes easier to plot ).
This is one data point on your jetting chart - but you must be sure that your test run time and water temps match what is seen on track.
So from now on , be it on the dyno , or at the track , you have a target EGT.


Thank you VERY MUCH!

/Screenshot saved.


We will be following this procedure to a T.

PerformanceTrends sold us a whole range of K-type thermocouples, with one specifically a "fast response" unit for measuring EGT; we will see how well it works.

-I know you have a preferred 'fast response' thermocouple, but I dont have the part number saved, do you mind digging it up for me?

Thanks again!


-Sean

[Flettner]

Inside the AG cylinder, for what its worth.

[husaberg]

Looking at that helical primary and knowing how bad those ratios are I can't help but think that MB100 or a DT175 would make a better bottom end stating point. I will see if I can find you some AG175 bottom ends, pretty sure the 6 speed DT ratios would go in, or MX ones
That said the finish on the cylinder fining is amazing Neil, a real credit to your craftsmanship.

[wobbly]

https://www.exhaustgas.com/ProductDetail.asp?ProductID=2077&DepartmentID=20&CategoryID=98&MenuID=sub1&BasketID=

Stinger open tip , can be ordered with any length of extension - only probe with a 2 year warranty.
I have sold literally hundreds for karting use - never had a probe failure.

[Flettner]

Looking at that helical primary and knowing how bad those ratios are I can't help but think that MB100 or a DT175 would make a better bottom end stating point. I will see if I can find you some AG175 bottom ends, pretty sure the 6 speed DT ratios would go in, or MX ones
That said the finish on the cylinder fining is amazing Neil, a real credit to your craftsmanship.

I'm useing DT100 crank gear and clutch basket, higher gears ratio than the AG. Also allows for fitment of AG200 plates and springs. Much stronger.
Finish, yes I'm happy how the cylinder cast but if you zoom in you can see the bottom fin, a bit rough but good enough for a one off test unit.

[SwePatrick]

I see you talk about jetting carburetors, money saving tip!
This is my take on getting into the ballpark without spending dollars on buying a lot of rods(lectron)
When engine is somewhat running good after grinding the rod, you can measure it and buy the ones that are most similar to your grind.
Or, if it actually just wokrs fine, keep the grinded rod =)

Part one:

https://youtu.be/Jdj3NZGLwNU?si=Y8EqeUxh1oCGQ1je

Part 'two':

https://youtu.be/Rf5fk2iAJgs?si=WJkqAyfFX1yOc0zc

[rtechracing]

Does anyone have a copy of the SAE 850085A and 930503 papers refered to in the FOS Air density correction factor? I will send them to Performance Trends so that they can implement the FOS correction in their dyno software.

Thanks

[ApolloMotoMoto]

Does anyone have a copy of the SAE 850085A and 930503 papers refered to in the FOS Air density correction factor? I will send them to Performance Trends so that they can implement the FOS correction in their dyno software.

Thanks

TEST


SAE 850085 should be attached to this post as a downloadable PDF.

[ApolloMotoMoto]

Does anyone have a copy of the SAE 850085A and 930503 papers refered to in the FOS Air density correction factor? I will send them to Performance Trends so that they can implement the FOS correction in their dyno software.

Thanks

Working on aquiring 930503:

Harari, R., Sher, E., The Effect of Ambient Pressure on the Performance Map of a Two-Stroke SI Engine
-SAE International Congress & Exposition, Detroit,MI, Pg 115-123, 01 March 1993.

Looks like I am going to have to just pay for it directly from the SAE.

[ApolloMotoMoto]

Does anyone have a copy of the SAE 850085A and 930503 papers refered to in the FOS Air density correction factor? I will send them to Performance Trends so that they can implement the FOS correction in their dyno software.

Thanks

$39 USD later, and without further ado:


SAE 930503

Harari, R., Sher, E., The Effect of Ambient Pressure on the Performance Map of a Two-Stroke SI Engine
-SAE International Congress & Exposition, Detroit,MI, Pg 115-123, 01 March 1993.

(attached)

[rtechracing]

$39 USD later, and without further ado:


SAE 930503

Harari, R., Sher, E., The Effect of Ambient Pressure on the Performance Map of a Two-Stroke SI Engine
-SAE International Congress & Exposition, Detroit,MI, Pg 115-123, 01 March 1993.

(attached)

Would you like me to split the cost with you?

Do you have the SAE paper 890836 as well?

[ApolloMotoMoto]

Would you like me to split the cost with you?

Do you have the SAE paper 890836 as well?

Thats quite alright, I wanted it for my own records as well.

If you can get PerformanceTrends to include the FOS 2-Stroke correction factor in their Dyno software, I would consider that payment in full :D

I can not find SAE 890836 available as a free download anywhere so far;

It is available for direct purchase from the SAE MOBIUS here:

https://www.sae.org/publications/technical-papers/content/890836/

[rtechracing]

Thats quite alright, I wanted it for my own records as well.

If you can get PerformanceTrends to include the FOS 2-Stroke correction factor in their Dyno software, I would consider that payment in full :D

I can not find SAE 890836 available as a free download anywhere so far;

It is available for direct purchase from the SAE MOBIUS here:

https://www.sae.org/publications/technical-papers/content/890836/

I am in dialog with Performance Trends. I get the impression that they are willing to do it since they asked also for 890836 as it was refered to in one of the other SAE papers

[rtechracing]

Thats quite alright, I wanted it for my own records as well.

If you can get PerformanceTrends to include the FOS 2-Stroke correction factor in their Dyno software, I would consider that payment in full :D

I can not find SAE 890836 available as a free download anywhere so far;

It is available for direct purchase from the SAE MOBIUS here:

https://www.sae.org/publications/technical-papers/content/890836/

I bought the SAE 890836 so if anyone would like a copy, please explain how I add it to a post:facepalm::yes:

[husaberg]

please explain how I add it to a post:facepalm::yes:
https://www.kiwibiker.co.nz/forums/album.php?albumid=4916&attachmentid=309281

https://www.kiwibiker.co.nz/forums/album.php?albumid=4916&attachmentid=309281

[ApolloMotoMoto]

I bought the SAE 890836 so if anyone would like a copy, please explain how I add it to a post:facepalm::yes:

Awesome!

Thank you very much!

The team I work with has also been in contact with PerformanceTrends, and we also requested that they add the FOS 2-Stroke correction factor.

Hopefully with enough pressure and with the support of the published data they will see fit to add it to their software.

[SwePatrick]

I noticed you were talking about jetting and such, i´ll contribute with my redneck method of getting a lectron into the ballpark if having just one metering rod, and don't want to buy so many before getting it right =)


https://youtu.be/Jdj3NZGLwNU?si=_okTWrzH2FlQy0Ey

And the missing part:

https://youtu.be/Rf5fk2iAJgs?si=kPm40LQmFgeQjAxo

Lastly, the result, not fully tuned yet, but full throttle seems to get close.

https://youtu.be/-k8xzb0CiEM?si=OEW09aaBoiXgyiSr

[wobbly]

So Patrick ,after you telling the internet with absolute certainty, I was completely wrong about dyno losses , now suddenly - quote " I dont know".
As I told you several times, doing a run down with the clutch pulled in, is not even remotely a valid test of this metric.
SportDevices has an easily accessed % transmission losses entry page under Corrections - where you can enter 15% or anything that will give you the data as seen as crank power in your simulation.

[ApolloMotoMoto]

I am happy to report, thanks to R-Tech Racing's efforts and the collegiate sharing of research...

PerformanceTrends just sent over a new version of their Dyno DataMite Software for validation testing.
-Updated to include FOS 2-Stroke Weather Correction Factor!

Assuming all works as expected, the new update should be available for download pretty soon.

Thank you Frits, Wayne and R-Tech Racing! :D

We had honestly given up hope, and were preparing to purchase the SportsDevices DAQ and Software.

This success saves my team ~$1,000 USD that we had basically already commited to spending.

We are VERY excited to have this result.

[wobbly]

I have sent 2 screen shots with differing weather to Rein, showing the FOS corrections to send to Performance Trends so they can confirm the code changes needed are correct.

[ApolloMotoMoto]

I have sent 2 screen shots with differing weather to Rein, showing the FOS corrections to send to Performance Trends so they can confirm the code changes needed are correct.

As part of the conversation, we had shared many screenshots of comments you and Frits had made on the subject, here and on Facebook.
-screenshot included

Your input was important in getting this across the finish line.

;)

[Frits Overmars]

I am happy to report, thanks to R-Tech Racing's efforts and the collegiate sharing of research... PerformanceTrends just sent over a new version of their Dyno DataMite Software for validation testing -Updated to include FOS 2-Stroke Weather Correction Factor! Thank you Frits, Wayne and R-Tech Racing!We are VERY excited to have this result.I am VERY happy to hear it ApolloMotoMoto.
One small remark: I call it the FOS two-stroke air density correction factor instead of weather correction factor. Thankfully most dyno rooms are shielded from the weather so the air temperature and pressure in a good dyno room can adjusted independent from the weather.

[Frits Overmars]

Of course there are exceptions :msn-wink:
355485 355486
Before anyone gets the wrong impression: I have the utmost respect for Neil's achievements but these pics were too nice not to use them :D

[41juergen]

I am VERY happy to hear it ApolloMotoMoto.
One small remark: I call it the FOS two-stroke air density correction factor instead of weather correction factor. Thankfully most dyno rooms are shielded from the weather so the air temperature and pressure in a good dyno room can adjusted independent from the weather.

Sorry Frits, the search function makes me nuts, can you share that again, I would try to see if DynoJet would also implement that in their software..

Edit: done, got that already from Neels... thank's a lot!

[wobbly]

Me thinks you are spoiled rotten by the SOTA apparatus at Aprilia Frits.
The only " shield " most dyno rooms have from the ambient weather is the workshop front door.
If I could be bothered , the best/worst pics of Neil is a couple showing his knees in his mid winter shorts - a horror nightmare show not many have survived psychologically intact.

I wonder out loud if the code guy at Performance Trends didnt want people ringing him and mistakenly calling him Richard.
Really glad prodding the Bear actually worked in this case.

For those people who have not actually seen the FOS code in action , here is a shot of the real time screen on my dyno.
The SportDyno digital weather station is calibrated to the local airport, about 5Km away.

[F5 Dave]

I was using the same dynojet for maybe 25 years but running it myself for 10-15, heck time flies. Mostly it was arrive after dinner, roller door up, dirty big fan on, rug up of it was cold.
Turn off any correction. What you did that night was measured in apples so improvement (or usually deprovements) could be measured. Previous runs were taken with grain of salt.

For a short while Chris built a room in room with extraction and inlet. Didn't know we were born.

[Frits Overmars]

Sorry Frits, the search function makes me nuts, can you share that again, I would try to see if DynoJet would also implement that in their software.. Edit: done, got that already from Neels... thank's a lot!Thanks Neels.
You can find the 'FOS two-stroke air density correction factor.PDF' in 'FOS tips & concepts':
https://onedrive.live.com/?authkey=%21ABfdzwPhevl4qMs&id=8DD58EFB966FB3DC%216309&cid=8DD58EFB966FB3DC


Thankfully most dyno rooms are shielded from the weather so the air temperature and pressure in a good dyno room can adjusted independent from the weather.
Me thinks you are spoiled rotten by the SOTA apparatus at Aprilia Frits. The only " shield " most dyno rooms have from the ambient weather is the workshop front door.You should have seen my dyno room in 1978: an inertia flywheel built out of two tractor flywheels welded back to back, plus a Heenan & Froude water brake, salvaged from a technical university that was going to throw it away after 20 years of service, coupled to a central heating radiator with long hoses, so I could put the radiator outside the dyno room in summer and inside in winter.
There was a blower for engine cooling that accidentally cooled the exhaust pipe more than the engine radiator, which taught me not to cool the pipe too much, and a fumes extractor, sucking the exhaust gases through a giant bong that caught most of the smoke and smell in order to keep the neighbours at peace. Finetuning of cabin temperature and pressure was done by opening the door more or less, provided there was no one else in the building trying to make a phone call.

The Aprilia dyno department was a somewhat different kettle of fish. Controlling the air humidity was taken care of by an air conditioner that cooled all incoming air, condensing the water vapor, and then heating that air up again to the required temperature. That airco consumed about as much electricity as Aprilia's home town Noale.
355500355499355498355497355501355502

[Frank S.]

... just to make you guys a little jealous, that's where I work
:cool:
355503

[ApolloMotoMoto]

I have sent 2 screen shots with differing weather to Rein, showing the FOS corrections to send to Performance Trends so they can confirm the code changes needed are correct.

(...)

For those people who have not actually seen the FOS code in action , here is a shot of the real time screen on my dyno.
The SportDyno digital weather station is calibrated to the local airport, about 5Km away.

Heya Wayne, I just got an email from PerformanceTrends this moring saying they had not received these two screenshots from the SportsDevices software so they can confirm the code is working properly;


Can you post that other screenshot here?

***EDIT***

-JUST NOW received another email from PerformanceTrends, they just got the email with the SportsDevices screenshots (both of them) ;)

Thanks again!