I have three of these motors and I do have overheating problems if I run full throttle for more than 3 or 4 minutes. All of mine are fully cowled with baffles and pitts mufflers which drastically contribute to the heating problem (IMHO). I can reduce or eliminate the overheating problem if fly mostly at 1/2 throttle with short bursts or moments at full. I changed all of them over to the new needle valve/body assembly so we'll see if this solves the problem when flying season starts again in a couple months.