This is a paragraph that Rich wrote on "GAS"
This all brings us back to the octane question : How much do you need. We'll go into more detail in Part II of the series but here are a few suggestions to get you started:
Start simple and work your way up. Try a good grade of premium gas that doesn't contain ANY ALCOHOL. In most states they will have a sign on the side of the pump warning you about the percentage of alcohol (ethanol or methanol) in the fuel. Most well modified normally aspirated engines can run on 95 -100 octane gasoline. Good porting with flow matched transfer ports can significantly lower octane requirement on two cycle engines. If your engine detonates try one (or all) of the measures to lower the octane requirement of the engine. If all these measures fail, try mixing pump gas 50/50 with a good of good quality race gas (Phillips 66, Power Mist, UNION 76, Sunoco, VP, ELF, etc..) with your gasoline. Make sure you use race gas specifically designed for you your type of application. The fuel manufacturers can make recommendations based on your engines rpm range, bore size, and the type of riding you'll be doing. It's best to stay away from AvGas for your bike. We'll go into the specifics of AvGas in the next installment. Keep in mind that octane requirement is lower at high altitude and high humidity. An engine that ran fine at 10,000 feet could very easily detonate at sea-level, or a sudden drop in humidity on a hot day can cause knocking that never appeared before.
Like I said, I's YOUR bike run what you want.
For some reason I trust Mitch Payton?
Regards