I JUST GOT MY MOTOR BACK FROM THE BUILDER BECAUSE OF THIS PROBLEM. I BLEW A QUARTER SIZE HOLE THROUGH MY RIGHT PISTON AND MELTED THE TOP PORTION OF THE ROD. MY BUILDER TOLD ME IT WAS A COMBINATION OF POOR FUEL, HIGH COMPRESSION, AND BAD TIMING. I NOW REMOVED MY DEGREE KEY AND RUN AV GAS. I ALSO REJETTED TO 310 MAINS W/30 PIOLTS....THE SHEE SCREAMS LIKE NO OTHER