another perfectly good motorcycle ruined.......

Friday, 19 February 2010


not much to look at i admit but a crucial part of the racer project, this is the expansion chamber, the class rules state that the exhaust header pipe and the first diffuser cone have to be standard, we have cheated a little by using the header pipe from the earlier ts250 model which is a better shape for performance and also to allow us to tuck the exhaust under the engine so that it exits on the left rather than the right as on a standard machine, the reason?, most tracks are predominantly right handers so we gain ground clearance, two stroke tuning is a black art, i have lost hours researching on the interweb, what i have determined is that we are basically bolloxed using the small diameter header pipe and the small chamber diameter, compression ratio, ignition timing and the temperature of the spent exhaust gases combined with the port duration, [we are using a piston ported engine, no reeds], effect the performance, we really need a tapered header pipe when you look at the tuning models available but the rules state you have to use a standard item, which, on inspection looks like it has no taper at all, dead frustrating really, like i said before, slap a mikuni 42mm carb on and go for a tapered header and fat belly chamber and they would really move.

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