I put about 3 gallons of fuel through mine before the piston and sleeve needed to be replaced. I just broke in the new piston and sleeve and is running good so far. I let my son race it in the 1/8th scale buggy sportsmen class in a Matrix with it now. It's got plenty of power for him as it is not as competative of a class. Replaced the roto start with a standard bump start only backplate too. Not a bad engine, just not powerful enough for hardcore racing imo.