Octane Rating

[Gumby 1100_imp]

I asked this in another thread, but this seems like a good place to re-ask:

I have read that bikes like mine with the cat. removed and the stock (and unfleshed) ecu will tend to run on the rich side. Would running with higher octane fuel improve performance in this situation? Note: I understand that the actual mixture would still be rich, but would the higher octane gasoline burn better in this situation?

Not likely, as higher octane fuel contains combustion inhibitors. Lower octane fuel is actually more volatile. Higher octane fuel is designed for high compression engines. Without the octane (inhibitors) it would combust prematurely due to the higher compression.

As CIP57 noted, he was smelling more unburned fuel when using the higher octane. In other words, don't waste your money on high octane fuel for a bike with relatively low compression and designed to use low octane. High octane fuel in a low compression engine may even cause plug fouling, carbon deposit issues and, in some cases, additional decel popping (due to incomplete combustion).