I bought a 98 blaster and it needed a top end rebuild. So i had the jug bored and bought a new wsm piston, and cleaned the carb. I put it all back together and i ran fine for the first half a tank of gas mixing 32.1. running 93 octane. First i noticed it was kind of slugish then the motor started backfiring and stalling. Dont know whats wrong with it need advice. It has fmf pipes and bosen reeds. thanks