Anything over 10:1 compression and you should use 91 octane or better to be safe. It won't hurt anything to run race fuel, but you won't really gain anything over running your basic pump 91 octane.

Once you get in the he 12:1 ratios, you need to move up to at least 93-94 octane. Some guys that high will run some sort of race fuel or octane boost mix, but a lot will just use one of the good 93-94 octanes like Sunoco or Mobile.

The one benefit of running "super" grade fuels, is that they have more stabilizers and will last longer in the can. I generally run 91 in my z400, and because I use the same can my Wife's Raptor350 and our Rancher350 also run on a steady diet of 91. Both the Rancher and the Raptor run like champs on the 91, but I could easily use 87 in them both and probably have no issues.

 

I do use premium fuel but no matter how I jetted it it wasnt right. So I said what the hell and put a little alcohol and it runs fine now.