Ok I have a new top end bored to next oversize and a rebuilt carb with boyesen power reeds. I run premix. I want to run with airbox lid off. Stock exhaust. What size jet should I run? It currently has stock sized jet. Also If I run with the airbox lid off and a stock jet will this blow my engine? Also how many turns out should the air screw be on the carb? Or do I need to adjust that with the engine running to get the best tune?