Jett .50
Bob,
Very helpfull. You are right on about "lean" being the cause. The engine and plane were purchased together. The only changes I made was fuel and RPM (increase). My buddy was set at about 16,750. I tweeked it to 17,000 AND changed fuel from 15% to 20% nitro. Next trip to the field I will start by reducing the top end to 16,750 and see how it goes. The tank is wrapped very well in foam so if a lower RPM doesn't work I will try a different tank. Take Care.