You dont want to use less then 90, so 91-94 are the best.
I use Sunoco 92, Pioneer has 93 which is good too.
Dont use Sunoco Ultra94, the methanol/alcohol level is too high for motorcycle engines, it could cause damage over time.
I have an 86 zx6r and I read on a sticker inside under the rear seat that I should run 91 or higher, one time I put in Sunoco Ultra 94 (which my friend who works at a sunoco tells me is actualy closer to 95) and I didn't really notice a difference. a Friend of mine put it in his 98 Katana 600 and said the bike actually ran worse and ran hotter because of it. so neither one of us have used it, we both stick to 93.
Best thing to do is to try a gallon of all three octane levels, and see which one you like best.
Next time you hit reserve, zip over to the nearest gas station and add a gallon of whatever oct. Ride until you have to switch to reserve, and memorise the mileage. Then try the other two octanes just like this. Whichever one gives you the best blend of mileage and throttle response is the one you should go with.
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