RE: Saito shuts off
Ok then try the smaller diameter prop 12x7 and see what happen. If you say there is hardly any carbon then it may just be that the engine is still not properly broken in yet. In that case be patient and run it at half throttle for another 16 oz and slowly work your way back up to full after the 16 oz. Another thing is to check all screws make sure they are all tight. Check carb for secure. Hope you are using good fuel with no water in it. Water in the fuel can also cause those symptoms.