I finally got the little guys machine together and running. It's a 90cc engine that came from some unknown brand ATV that was sitting in my neighbors yard for the past 5 years! Anyway For the sheave I used what came with the 90 and the clutch side has a 1500 spring and not sure what the smaler springs are but this was the best combination from the parts I have. The gearing is 19/32 and using the belt that came on the 90. It seems to be reaching the proper RPM but still seems a bit off. Whats a good way to know if you need to tweak the clutch or the gearing? A tach would be a good investment too?