Interesting. Thank you both for your input. So Harv am I right in summing your post up by saying max power is unlikely to be effected by a large amount. But what will change more so will be the point at which the "power band" comes in? So jealous of you doing the karting, I have always wanted to do that! Motocross seems another option though hence my interest!
You are correct chip , its why the expansion is there in the exhaust then a small outlet .
Every last little thing has an effect on a 2 stroke , from barometric air pressure and density to exhaust design and flow. you are correct in assuming it affects where the power band will be , back in the 90's when i raced full race very high spec aircooled engines the exhaust length was varied to deliver optimum power delivery at a given circuit ,
these engines we could vary jetting on the fly and you would run a 2stroke as lean as you dare to get the maximum out of it but your risk of seizing was close all the time hence at the end of a long straight you would see a driver momentarily cover an airbox to dump a rich feul mixture to cool an engine at the point of going bang .
More modern rotax max engines are found on the road in any number of 125cc scooters and motorbikes , they have more liberal tolerances and have fixed jets which you can change prior to running .
the computer program we ran to give optimum jet size was fairly comprehensive .
I am by no means a master of 2 strokes but after 33 years racing them on and off i have learnt a few things ........ a stock cast head 2 stroke engine has huge scope for the home tuner if you ever get one to play with ...
