ESE's works engine tuner

[Wos]

in Classic enduro Championship race at Nordhausen/ Germany... have a look on the brick

[Flettner]

Aren't you guys getting tired of having to look at my thumb for over a week now? I know I am

Whenever I post, it kills this thread ... the kiss of thread death.
😁

[Frits Overmars]

Whenever I post, it kills this thread ... the kiss of thread death 😁

If you really have that power, I can think of a few other forums you could visit

[Condyn]

Hello fellow sufferers, I have been stumped by something for a bit now. I drag race an air cooled snowmobile which uses a CVT (not sure of relevance but just to be complete I included)
I always have excessive wash width of 10mm on a 69.5mm bore, and rich plugs along with a chalky white thread base ring.
My engine responds well to jet changes, however when I go down a size from my known sweet spot EGT, the EGT increases again in a normal increment. This narrows my wash pattern, but the engine has a lean feeling on the warm up stand and my Elapsed time always gets worse. I have 130 logged passes and have rider awareness with this machine. It is a front runner (but I want it perfect lol)

This almost suggests to me that there is a mismatch with the compression ratio and or ignition timing at peak operating rpm on the cvt. Maybe something else?

-Comp ratio 15.5:1
-fuel c12
-ignition straight line 15 degrees
-spark plug Br9es
-stinger diameter 23.6x300 (no nozzle currently because it has always performed better better with full length stingers, maybe a much smaller nozzle than I have used is in order)

Am I beating myself up for nothing, or does anyone have suggestions to make my setup more synergetic?

[lohring]

The part of the text down to where it says "Jim Allen" is from Jim. The rest of the text is from Bill Givens. I like Jim's fixture, but both people have great insights. Jim mostly rebuilt small engines (26 cc) while Bill rebuilt larger engines.

Lohring Miller

[Frits Overmars]

The part of the text down to where it says "Jim Allen" is from Jim. The rest of the text is from Bill Givens. I like Jim's fixture, but both people have great insights. Jim mostly rebuilt small engines (26 cc) while Bill rebuilt larger engines.
Lohring Miller

Thank you Lohring.

[wobbly]

Condyn, what is the actual cylinder displacement - ie what is the stroke.
15.5 com is nothing for C12.
This is 2025, why are you using a straight line ignition from the 1970's.
Also a spark plug from a lawn mower.
What is the " sweet " EGT at what rpm, is this derived from a dyno run and if so what power is it making.
Many more questions to get some analysis, but this is a start.

[Condyn]

Wobbly, it is 452cc. 69.5x59.6 I use the straightline ignition because at many venues that I race, the rules state that a stock ignition must be installed. It is a vintage class from the 70’s. The egt is right at 650c at 9500 rpm, 3x bore from the piston. No, I am familiar with your logical jet selection chart, however I did not have the chance to install the probes on the dyno during the last session.

The field tests tell me that when I jet down it goes slower. I looked again with my wash light last night and I might be wrong on the wash width. It looked more narrow (around 5-6mm) I am going to take the heads off tonight to get better eyes on it. The piece that keeps me up at night is the egt continues to rise with a down jet (650 up to 670) however it makes a pop on the warm up stand at full rev and makes my pass slower by a tenth every time. Admittedly I do not always have the cht hooked up so I am not aware what the cht is doing when I jet down.