ESE's works engine tuner

[TZ350]

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Ok, I am trying to make sense of Jetting for the F81 Beast as I will have to resort to custom drilling my own. This is something I scraped from the net:-

Mikuni hex head jets are numbered by bulk flow, while Mikuni round head jets and Keihn jets are numbered by inner diameter in mm.

The flow difference between a Mikuni 175 hex jet and a 180 is about 6cc ~3%) . Keihn jets are numbered by jet id, and the difference between a 178 and a 180 is about .0008" (I'll let those so inclined do the math to determine the flow difference) .

Now to further confuse the issue keep in mind that air/fuel ratio is based on weight of fuel and weight of air, but jets essentially meter by volume. So we really need to know the weight of the fuel flowing through a jet to understand all this. In simplest terms fuel weight is a function of the area of the jet multiplied by the value of the square root of the fuel head pressure multiplied by the density of the fuel.

It looks like this:
weight of fuel = jet area * ( SQR Root (head pressure * fuel density)

None of the above takes into consideration the changes in fuel vaporization characteristics as you change altitude, which can have a profound impact on the final air/fuel ratio available in the combustion chamber ( the only place a/f ratio is really significant anyway) when the sparkplug fires.

As fun as it might be to look at jetting this way, the sad fact is the cross sectional area of two jets marked with the same number can vary FAR MORE than the difference in flow due to small changes in density . Good jets can vary as much as 5% cheap jets can be closer to 10% variance.

Mikuni N100/604 large round pan head jets are measured in mm's so a 180 has a 1,8mm orifice.



Mikuni 4/042 large hex are measured in flow, so a 180 has an orifice that flows 180cc.



A 180 Mikuni N100/064 is measured and marked in a totally different way to a 180 Mikuni 4/042.

[DoldGuy]

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Ok, I am trying to make sense of Jetting for the F81 Beast as I will have to resort to custom drilling my own. This is something I scraped from the net:-

Mikuni hex head jets are numbered by bulk flow, while Mikuni round head jets and Keihn jets are numbered by inner diameter in mm.

The flow difference between a Mikuni 175 hex jet and a 180 is about 6cc ~3%) . Keihn jets are numbered by jet id, and the difference between a 178 and a 180 is about .0008" (I'll let those so inclined do the math to determine the flow difference) .

Now to further confuse the issue keep in mind that air/fuel ratio is based on weight of fuel and weight of air, but jets essentially meter by volume. So we really need to know the weight of the fuel flowing through a jet to understand all this. In simplest terms fuel weight is a function of the area of the jet multiplied by the value of the square root of the fuel head pressure multiplied by the density of the fuel.

It looks like this:
weight of fuel = jet area * ( SQR Root (head pressure * fuel density)

None of the above takes into consideration the changes in fuel vaporization characteristics as you change altitude, which can have a profound impact on the final air/fuel ratio available in the combustion chamber ( the only place a/f ratio is really significant anyway) when the sparkplug fires.

As fun as it might be to look at jetting this way, the sad fact is the cross sectional area of two jets marked with the same number can vary FAR MORE than the difference in flow due to small changes in density . Good jets can vary as much as 5% cheap jets can be closer to 10% variance.

TZ,
I’m glad to see the old beer can slide carb is providing its secondary benefit!

Reading your post from my phone, too dark for my eyes, but I’ve found if you can increase the area by 2.25 to 2.5 times from a properly running gas setting you’re in the ballpark. Also it’s much more forgiving on the too Rich side versus the too not enough.

[TZ350]

I’ve found if you can increase the area by 2.25 to 2.5 times from a properly running gas setting you’re in the ballpark. Also it’s much more forgiving on the too Rich side versus the too not enough.

Many thanks for the carb and battery. Increase area by 2.25 times I assume is for 100% methanol. Would 1.65 be suitable ball park for 50% Meth?

[DoldGuy]

Many thanks for the carb and battery. Increase area by 2.25 times I assume is for 100% methanol. Would 1.65 be suitable ball park for 50% Meth?

TZ, yes that’s 100% Methanol, If running 50/50 I’d start with 1.85 and confirm it’s plenty enough fuel, Methanol can be overly rich and still run fine.

Looking forward to your progress!

[mprestwi]

I was wondering if there would be any benefit to adding some form of horizontal ditch groove on the pipe side of a power valve (I.e. ypvs) to help stop the exhaust reversion pulse when it is closed at low rpm?

[Condyn]

Curious to what the CCR is on the TM KZ-R1, or any other modern, well developed reed engines. Trying to see how this compares to well developed RV engines such as the RSA.
With the obvious added job of opening the reeds, it is my assumption (dumb) that the reed motor would have a smaller case volume. If so, is this a shortcoming of reed engines, offering less for the pipe to pull on? Or are there other ways to achieve optimized intake resonance?

[TZ350]

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On the hunt for the reason gearbox oil is getting into the engine. I soaked the Kawasaki's rotary valve seal in a sample of the fuel I am using for an hour, 50% Meth, 45% 98 and 5% Acetone.

The seal did not like it much. Swelling up to the point where it had pulled right away from the drive. Maybe not the total answer but certainly a big part of the answer.

After the seal had been sitting out in the fresh air for a while it went back into shape. That probably explains why the bike started Ok, ran for a bit, smoked like hell and then ran real grumpy. After leaving it for a day or two it started up fine and ran Ok again for a bit then became grumpy. The next day when I pulled it down the seal looked ok until I soaked it.

[TZ350]

it is my assumption (dumb) that the reed motor would have a smaller case volume. If so, is this a shortcoming of reed engines, offering less for the pipe to pull on? Or are there other ways to achieve optimized intake resonance?

Not such a dumb assumption. Reeds do seem to need help closing whereas the RV Aprilia apparently made more power with every increase in crankcase volume. They did not seem to find the upper limit.

The Suzuki GP125 special of team ESE's. A special de stroked 110cc rotary valve unit with a NSR cylinder fitted had a very big crankcase volume. The cases and big end pin were widened by 12mm. The inner face of the flywheels trimmed back to the b/e thrust washer faces and the rod was 25mm longer than stock. Massive crankcase volume. The engine still started easily and made more power then ever.

[F5 Dave]

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On the hunt for the reason gearbox oil is getting into the engine. I soaked the Kawasaki's rotary valve seal in a sample of the fuel I am using for an hour, 50% Meth, 45% 98 and 5% Acetone.

The seal did not like it much. Swelling up to the point where it had pulled right away from the drive. Maybe not the total answer but certainly a big part of the answer.

After the seal had been sitting out in the fresh air for a while it went back into shape. That probably explains why the bike started Ok, ran for a bit, smoked like hell and then ran real grumpy. After leaving it for a day or two it started up fine and ran Ok again for a bit then became grumpy. The next day when I pulled it down the seal looked ok until I soaked it.

That's nasty Rob. Real nasty.

[Grumph]

Can you make up a mechanical labyrinth type seal for that side ? I'm sure husa can post something about the seals Wooley used in Greeves cases.

[husaberg]

Can you make up a mechanical labyrinth type seal for that side ? I'm sure husa can post something about the seals Wooley used in Greeves cases.

Telflon works okay with Methanol i sent rob some combability stuff
https://www.methanol.org/wp-content/...ol-Service.pdf



i had posted the piston ring seals before Ken was going to dyno one.
its easy enough to find.

Sometime ago Hooser got me excited. Nah, nothing to do the (or his?) whole chicken thing, but labyrinth seals (see pic). HP just waiting to be unleashed?
So, got a Ø20*Ø35*7 teflon lipped seal and wrapped it with a paper strip, slid it over a crank and weighted it up so it was enough to overcome static friction and slowly rotate around the shaft with a 90 gm weight. (see pic).
Working backwards, this level of friction equates @ 14k rpm, to equal 0 .0226 kW. Stuff all really.
However, this is without and pressure acting on the seal. I guess the next step would be to mount 2 seals in a sleeve with varying applied pressures from within a drilling in the shaft. See pic. I guess one could do this based on crank angle vs pressure and do some sort of averaged calc of the frictional power over the full 360 deg cycle
Attachment 325069Attachment 325070Attachment 325071

Lab refers to the seal type, they can be a series of grooves like the Yamaha and others,
Attachment 322714

or a piston ring or rings in a groove
The first use of the piston ring seal i have seen was in the DKW triples.
pics to follow.
Note Teflon has likely rendered them not a HP saver.
Attachment 322713Attachment 322712Attachment 322711

PS will it wasn't the design offices it was the company directors and shareholders the brits had amazing designers, that were not able to build anything that would require money spent on retooling the factories.
Have a look at all the worlds motorsports they are designed and for a major part built in the UK.

[Condyn]

Not such a dumb assumption. Reeds do seem to need help closing whereas the RV Aprilia apparently made more power with every increase in crankcase volume. They did not seem to find the upper limit.

The Suzuki GP125 special of team ESE's. A special de stroked 110cc rotary valve unit with a NSR cylinder fitted had a very big crankcase volume. The cases and big end pin were widened by 12mm. The inner face of the flywheels trimmed back to the b/e thrust washer faces and the rod was 25mm longer than stock. Massive crankcase volume. The engine still started easily and made more power then ever.

Surely it was discussed earlier, but what carburetor size and rv timing did you end up with?

[F5 Dave]

We have class limits of 24mm for 125s, so perhaps not very relevant for comparison.

[TZ350]

Surely it was discussed earlier, but what carburetor size and rv timing did you end up with?

Carb. Class limit for two strokes over 100cc is 24mm. RV timing on the Team ESE RV engines is typically 145btdc/85atdc. Trans 113atdc. Ignitec ignition.

Things that Team ESE did to get more crankcase volume for their RV engine.

The cases and big end pin were widened by 12mm. The inner face of the flywheels trimmed back to the b/e thrust washer faces and the rod was 25mm longer than stock. Massive crankcase volume. The engine still started easily and made more power then ever.

[TZ350]

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The Kawasaki RV seal after soaking in Methanol mix for an hour.



The Kawasaki RV seal looks perfect again after it has dried out over night.

This is the same problem I had with RD250/350/400 Yamaha Teflon lipped seals back in the day. I had no problems with the Suzuki TR250R or any other Suzuki ones.