Hot70 - I see you are using Direct drive. Do you just pedal off to start? I have a folding bike with a direct drive but the engine has too much compression to do that. I am using a 7/8 roller and I think it needs to be larger, I don't need to go fast, but a higher gear will make it easier to start. I like making things on a simple scale. I used the engine off of a water pump, it actually had a shaft about 1/2 in diameter, I just sleeved it. It is a 45cc two smoke. I have three of them, all of them were left with water in the housing and there was nothing left to save in the pump. I used the belt material from a belt sander and then contact cement it to the shaft, overlapping in the direction of rotation to keep it from pealing off, I have only a few miles on it and the coarse belt is hard on the tires, I will have to buff it down. I am making a lever to move the engine off the tire at a stop. Thanks for making me think, I have not worked on this bike for years. Have fun, Dave