Higher Octane Gasoline

[F6Dave]

I run regular unleaded in my 2016 F6B and have never had a knock. But most of my riding is above 5000 feet. Our unleaded at these higher elevations 85 octane (possible because of the thinner air) and never a knock. Now, if I went down to lower elevations that could change. On my 2002 Wing when at lower elevations and on a really hot day I would get knocking when I cranked the throttle, so I would use a higher octane in those situations to avoid the knock. I think 2wheelsforme has it right!

My experience is similar. My 2016 has never knocked. I run 87 octane ethanol free most of the time, which is available 2 miles from my house. But I used to own a 2013 F6B that knocked on hot days. I remember one very hot day in particular. When I accelerated, I could hear the knock come and go several times. It happened very quickly, maybe over a second or two. I suspect the knock sensors signaled the engine management computer to retard the timing, and that process cycled a few times to get things right. It may have been a bad tank of gas, but in the future I always used premium on very hot days with that bike.

Some high performance cars, like Shelby Mustangs, state their claimed horsepower is reduced when anything but premium is used. I don't think they can actually measure the octane, so I assume they just retard the timing as soon as knocking is detected. I'd be curious if anyone knows more about this. Regardless, with the federal mandate that any new vehicle must 'run' on 87 octane, there are definitely some high performance engines that do make more power with higher octane gasoline.