To all the guys saying "don't be cheap, buy the highest octane", you all are wasting money. You should run the lowest octane possible without detonation/pinging. This will give the best performance while not causing carbon buildup. It's not that I'm cheap, I just want what's best for the bike. I run 93 in my truck, but it's tuned to run on 93. The bike is tuned to run on 91, I run 93 in it as well because most stations have 93 here, not 91. Now if the station has 91 that's what I put in. Technically I could put a gallon of 89 and a gallon of 93 to get 91, but that's a PITA.

The only reasonable argument here for running higher octane than necessary is this one:

air cooled engines can run very hot (and the tendency to cool unevenly, leaving hotspots in the cylinder walls at combustion chamber), which can cause pinging and knocking (which can damage your engine). Higher grade/octane fuels mitigate knocking. It's pretty simple: use the high octane gas to prevent potential engine damage.