120sp surging
have a sp 120 in my new skyraider, ran great on the stand, using coolpower 10% fuel, i have run about 2.5 gallons through the engine and now mounted it in the plane and first problem i had was the muffler too hot and burning the cowl. the exhaust from this engine is very hot, but another problem that i havent fixed yet is the motor surges at full throttle, I am pretty sure the problem is fuel foaming from the vibration of the engine, any sugestions? i dont think i can rap in foam. i hate to get rid of this engine as it fits the plane nicely, please help. thanks