I am upgrading the engine 49cc to 72cc (two strokes based on minarelli design - suzuki turbo). For the moment being I am just going to upgrade the engine, I will rejet the carb next week though (hope there is no big deal in running it with same jets for a short space of time). I have a few newbie question though: I install the piston with its two orifices facing the upper portion of the engine (not the exhaust port), wich I suppose the right orientation? I did use ring install tool in order to install the rings on the pistion, but I haven't gapped the ring or used a ring compression tool; would there be any problem? I am going to use the same spark plug that I was using when it was 49cc, sounds ok? Once I installed the upgrade kit and measured the compression I obtained 120PSI (which was the same compression ration that I obtained when it was 49cc).
Thanks for any help,