There seam to be conflicting opinions on this subject.
I have always bean told that higher octane fuel would make more power, but now I read articles that state 89 octane fuel burns hotter and faster which will make more power in a stock low compression motor.
High octane fuel is only for high compression motors, it burns cooler and slower, which prevents detonation. It seams odd to me that lower grade fuel will make more power in a stock motor, but that is what I hear.
If you have any input on this let me know.

 

Mega

In an effort not to recreate the wheel, I brought an old thread that I did last December about gas octane ratings. See my thread "Higher Octane Gas". Hope this answers your questions.

 

Thanks for the info, thought it was probably true but wanted a second opinion before I stopped buying the good stuff. That is untill I get the 65 pluss horse kit from HPD. (just dreamin)

 

Octane does not make horsepower period. As long as your motor is not preigniting or knocking then you are ok. If your bikes are stock then any grade should be fine, I run C-12 108 (ACTUAL RATING NOT THE RATING AT THE PUMP) leaded gas in my zilla's and my sisters 400 highly modded 14 to 1 compression scrambler. But in everything else I usually Run super unlead to to make sure i don't have any probs, but the regular is fine to. The only time you need race gas is when you build up your motor and the only thing it does is keep the motor from preigniting, The lead in race fuel however is a lubricant and helps reduce where.