id been looking for ages for something to fit and in desperation i went to see a friend who runs bike shop, he took the piston and has matched it up with another one. single ring and its compatable with the barrel. the only thing thats not quite right is that the dimention from the pin to the crown of the piston is 0.3mm shorter.
the theory is try it with standard gaskets first (it should give better over rev) and then have a go with thinner base gaskets.
it will be checked on a rolling road before i advise anyone else to do it. so if im upset next week you'll know it must have ended in tears
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wadda ya mean its too fast!