A few other things to consider about the heat thing, if your plug is worn out and your not getting enough power to lock the clutch at low end, it will tend to burn the bearings out. In effect it makes it over geared for your set up cause your current gearing now cant be pushed as easy with the reduced power of the motor due to a worn out plug. One last thing, the clutches themselves worn out, can cause them to produce more heat, killing off bearings. I learned that heat issues is more damaging than most people know about. The heat not only wears out your clutch bearings but remember it goes right through the crankshaft and right on the front bearing in the motor. Before I learned how damaging it really was, my first motor had grooves in the crank after 9 gallons from the clutch bearings. All the little things just to get these nitro's running in optimal condition makes me want to switch to electric. Currently, I am playing around with adjusting cooling on the motor as well as the standard tuning to prolong engine life and get more power through out the life of the motors