My manual says to run 91 or greater octane, so I've religiously run 93 octane Texaco gas. Recently I was low on gas and there were no gas stations around other than a 76 and they only had 91 octane fuel. After filling up I noticed that my motorcycle was running significantly smoother. There are no longer any sudden drops in rpm, and my engine rpm stays even throughout the powerband.
Is it smoother because I'm using closer to the recommended octane? Or is this because of the quality of the gas? I had always assumed that using a higher octane wouldn't have a noticeable difference in performance, but it sure did (for the worse).
Motorcycle: 2017 Yamaha R6 (Factory recommended minimum octane is 91)
Weather/Temperature: Hot and humid
Elevation: Sea level