ESE's works engine tuner

[F5 Dave]

Interesting read thank you, things I hadn't considered, not that I'm intending on trying. Just one typo I noticed on 'liter' and I only mention it in the best intentions, I have only one language and can't imagine how it must be with spelling.

Thanks again.

[Frits Overmars]

Interesting read thank you, things I hadn't considered, not that I'm intending on trying. Just one typo I noticed on 'liter' and I only mention it in the best intentions, I have only one language and can't imagine how it must be with spelling.
Thanks again.

I am grateful for your remark Dave. I checked again and I noticed that it depends on the settings of the translation program.
If I choose British English, it should be litres and if I choose American English, it should be liters.
I'm going to choose liters now, which looks more natural to me anyway because it's the same as in my native language.

EDIT: I can't seem to substitute the PDF in my previous post, so I am going to delete the whole post and re-post it below with the corrected PDF.

[Frits Overmars]

For those of you using SportDevices dyno software I have got them to add FOS 2Stroke Correction capability.
I wont get a chance to run an engine with differing weather until next week , but I can already see that it has a much more realistic amount of correction for values that depart alot from Std Air than the J or SAE algorithms used previously.
Next addition I have asked for is RAD/Density Altitude to be added to the available metrics outputs , so its easy to begin constructing jet charts based on best power egt /weather data. Simple " Air Density " is of no use for tuning , that I know of anyway.
Cheers big time Frits.
Edit - Shit it just occurred to me I should have asked permission before requesting this to be included into a commercial product - my apologies Frits.

No worries Wob, I feel flattered. And there's nothing that cannot be made up with a bottle of high-octane booze

Speaking of which, I finally found the time to prepare an English version of my Petrol-Ethanol-Methanol-E85 treatise. Here it is.
Attachment 351698Attachment 351704

[ken seeber]

Pretty sure Rob (tz350)detailed it in here use piano wire as a search.
i watched by father do it once he did it with a brass screw or stud.

Ken Seeber of course might have an idea how to do it professional like as well

Hewsar, I'm not a pro ...shifting the AR pin is not something we do. However, there some thoughts:

Firstly removing the old pin. As Wobbly suggests, it can be filed away, but absolute care must be taken to ensure that the sealing face of the groove is not damaged. One could fit a shim between the bottom of the groove and the file to prevent any contact. Another option could be to mill/drill the back section of the (usual) boss cast in the inside of the piston. This could expose the inner end of the pin which then could be pressed inwards such that its end was below the bottom of the ring groove in the piston. Another option could be to spark erode the pin away.

OK, the old pin is now out of the way, so a new pin is required. This can be done horizontally (or near so) or vertically. This suits most flat (rail) rings where there is a top land. The AR pin is positioned such that it doesn’t break thru the sealing face of the ring groove. We use pins of around 8 long * Ø1.5 , slightly tapered on one end with a longitudinal slot to prevent possible hydraulic locking should there be any coolant etc in the hole when pressing in. Interference is around 0.05. Obviously it must be pressed in far enough to provide an adequate clearance behind the ears at the ring gap. Suitable pins could be easily made from piano wire.



Vertical pins are pushed down from the crown, and in the case of the early Yamaha KT100S piston around Ø1.0, far enough to enter a small shallow drilling in which the end of the pin is slightly bent over to prevent it escaping.



However for Dykes rings, which are essentially flush with the line of the crown shape, many are angled slightly downward to minimise the chance of the pin cracking the top of the crown because the pin is so close to the crown surface.


If you want to be really, really, really crude, (obviously not an Australian idea) one could notch out original (steel) ring so the gap is shifted to be in a blank area of the bore. Certainly not recommended for a CI ring. Let us know how that one goes.

[Frits Overmars]

I came across pins like these in Elko pistons, fitted by Rotax in the late 1970s. They caused terrible detonation. With massive pins the deto was completely gone.

Vertical pins are pushed down from the crown, and in the case of the early Yamaha KT100S piston around Ø1.0, far enough to enter a small shallow drilling in which the end of the pin is slightly bent over to prevent it escaping.

I know this scheme worked for Yamaha but it didn't work for us. Unless the bore between the ring groove and the 'shallow drilling' is really, really long, bending the pin's lower end will hurt the press fit of the pin in the bore enough so that it will eventually work loose and wreck havoc. Our solution was to close the top end of the pin bore by welding.

[karter444]

Hewsar, I'm not a pro ...shifting the AR pin is not something we do. However, there some thoughts:

Firstly removing the old pin. As Wobbly suggests, it can be filed away, but absolute care must be taken to ensure that the sealing face of the groove is not damaged. One could fit a shim between the bottom of the groove and the file to prevent any contact. Another option could be to mill/drill the back section of the (usual) boss cast in the inside of the piston. This could expose the inner end of the pin which then could be pressed inwards such that its end was below the bottom of the ring groove in the piston. Another option could be to spark erode the pin away.

OK, the old pin is now out of the way, so a new pin is required. This can be done horizontally (or near so) or vertically. This suits most flat (rail) rings where there is a top land. The AR pin is positioned such that it doesn’t break thru the sealing face of the ring groove. We use pins of around 8 long * Ø1.5 , slightly tapered on one end with a longitudinal slot to prevent possible hydraulic locking should there be any coolant etc in the hole when pressing in. Interference is around 0.05. Obviously it must be pressed in far enough to provide an adequate clearance behind the ears at the ring gap. Suitable pins could be easily made from piano wire.



Vertical pins are pushed down from the crown, and in the case of the early Yamaha KT100S piston around Ø1.0, far enough to enter a small shallow drilling in which the end of the pin is slightly bent over to prevent it escaping.



However for Dykes rings, which are essentially flush with the line of the crown shape, many are angled slightly downward to minimise the chance of the pin cracking the top of the crown because the pin is so close to the crown surface.


If you want to be really, really, really crude, (obviously not an Australian idea) one could notch out original (steel) ring so the gap is shifted to be in a blank area of the bore. Certainly not recommended for a CI ring. Let us know how that one goes.

Thanks for the info Ken , I have replied to your email
cheers Richard

[husaberg]

from a few pages ago about grip
https://suspensionsecrets.co.uk/tyre...a-deeper-look/

[andreas]

Great Husa

[Condyn]

I am looking for a two stroke oriented cad/cam person in the states that I can easily send sample parts back and forth. If this is you, drop me a message.

[Javier Ruda]

Hi, I’m about to buy a single ring piston, maybe wossner maybe vertex. The wossner one has a blind hole on each side, around (b/c) a/b transfer ports.


No luck yet searching the posts. If anyone can tell me pros/cons I would be grateful.

[andreas]

The wossner is forged and the vertex is cast, thats probably a bigger difference than the "pockets", which I don't think do anything for performance.

[Javier Ruda]

The wossner is forged and the vertex is cast, thats probably a bigger difference than the "pockets", which I don't think do anything for performance.

Thank you andreas. I see that Vertex should run tighter clearance. Wossner is 0.05 mm and Vertex 0.03 mm I think. So if there is no performance gain, maybe cast is better, for having less themal expansion.

[andreas]

Cast has less thermal expansionand and usually cost less, while a forged piston is stronger.

[wobbly]

Pockets in the skirt always loose power.
Especially in a 3 port where the pocket adds to port linking between the A port and the Aux above it.
Back to back the new TM semi flat top with pockets in the skirts above the pin , looses between 0.5 and 0.75 Hp over a piston with exactly the same geometry
and no pockets.

And even without the Aux ports , the pockets suddenly add volume going over the transfers , this is part of the reason that pin plugs that fill the void thru the pin connecting to the transfer ports , add power when used.

Many of the Wossner forged pistons now have almost the same bore clearance as the cast versions.
0.03mm clearance is super tight , 0.05 is pretty usual for Wossners even in big piston sizes and high bmep applications.

[Javier Ruda]

Pockets in the skirt always loose power

Thank you wobbly. I will avoid pockets.

I did a search for recommended piston to wall clearance on rotax 125 cylinders:

1995 moto Aprilia RS125

0.020-0.035mm

2000 kart Rotax FR 125 Max

0.025-0.050 mm

2001 kart Rotax 125 Max Evo

0.04-0.05 mm

2021 kart Rotax 125 Max DD2 Evo

0.05 mm

And I remember now that I fitted the kart thermostat 45°C instead of the original Aprilia 70°C. Put all together, I think I will use 0.04 mm and avoid the super tight 0.03 mm.