I do know that going up in nitro is the same as going up in oxygen. That's what the nitro does. When you increased the nitro, it's like turning on more oxygen on a blow torch. The flame (in the case, combustion) gets hotter. This is why your engine is getting hotter. I would think that you may need to go richer. Running the engine richer will cut back on the air, thus cutting back on oxygen coming into the engine and compensate for the oxygen (nitro) in the fuel. Your engine is now getting more oxygen from the fuel and this makes a more powerful burn in the engine. Sometimes engines get too lean and they will wear all at once resulting in a loss of compression. I hope this is not the case with your engine. Older engines with a lot of use are especially vulnerable to this. I've seen this before in 2 cycle gasoline engines. Adjust the mixture screw too lean, and they kick the bucket! I am always afraid that this will happen when I pinch the line on my airplane engine to shut it off. Notice how they speed up for a second. Four stroke engines will sometimes burn a valve when they run out of gas because they get real lean right before they stop. Again, it's like turning on the oxygen in a blow torch. How about anyone else? Have any thoughts on the subject?