Yes on both questions.

First, the standard Gas/Glow mix calls for high test, or premium gasoline. We went to this because we encountered some detonation in certain engines with regular gas, and going to premium gasoline solved that problem. Second, you are running double the recommended nitro, and aparently that is just too much for the compression ratio of your engine.

You can try a batch with your high nitro fuel and high test gasoline and see what happens. You can try a colder glow plug if you have one too. If it keeps detonating though, you will have to go to a lower nitro mix. Detonation will kill an engine fast, especially a two stroke, so be careful.

AV8TOR