I would check the fuil line it mite have A hole in it when fuil level is high no problems as the fuil goes down during the flight the hole suck air you lean out and the motor dyes. I also like to use A large clunk it follows the fuil better. Most 4 stroks like to run rich at least my YS 63 and my YS 140 that is and they love 30% heli fuil. I hope this helps good luck.