I've used 91, 95, and 98 in my CBR250RR, with no noticable difference at all. I talked to some guys in Australia
(Honda JDM CBR forums) about it, and they reckon that 98 will create more carbon deposits, whilst 91 and 95 are both fine. So I use 91 when I pull into a gas station that has 91 or 98, and 95 when that's available. IIRC, when I used to work at a gas station, 95 has better properties to prevent knocking, but I don't know that much about it.
End of the day, my preference is 95. Plus, the mobil just up the road from me at the moment has the best prices on gas that I've seen on the whole North Shore, so that makes the decision easy - for 95, that is.
One thing to take into consideration is though, what gas was your bike last tuned on...? Being a carby engine, if it was tuned on 91, it'll probably run best on 91, don't you think?
Bookmarks