If your over reving the engine that will heat it up fast, you can use a MA skytach. I don't know the gearing of that heli but 1650-1700 would be a good range. The high nitro will keep that engine running hot also, if you stick with the 30% try running the high speed needle much richer say 2- 2 1/2. At that setting the engine will heat up but wont go lean.

My best recommendation is to put a 32-39 size engine in since that is what the heli was designed for.