I have discovered during my experiments with a 75ax trying put various props (from 13x6 to 14x8) to keep it cool that you dont necessarily need nitro. I found that this engine ran the coolest at 0% nitro. That may be geographic though. They recommend to add nitro for colder countries to help retain operating heat and to keep the engine from deadsticking at idle and hence to get the engine to idle better

Ameyam