Okay first... I do use 91 octane fuel which is the highest octane I have around here. That said, Why do we need the higher octane fuel and if it is better then why do they even offer lower octane fuels at stations? And a friend asked if he could run e85 in his Harley I told him no but I am not sure. Also should I get something to boost octane if I have to fill up with a lower rating (a few stations around here only carry 89)

 

I guess it depends what engine you have or what's done. I always run 93 in mine, I figure no more than it holds the price swing isn't a big deal.

 

I run 87 in my old evo and she runs strong. Once I was in the boonies dry and the only available fuel was 86 octane....she ran fine on that too. But then again, I'm talk'n about a real bike, not a twinkie. lol

 

Stock bikes today will run any grade with no issues but 91 is recommended , no you won't damage the engine nor do you need to worry about additives unless you've done some heavy motor work. Don't over think it these things aren't an airplane that can fall outa the sky over funky fuel.

 

There are five Harley's in my family. We all run 87. No need for higher octane on a low compression engine.

 

Higher octane fuel isn't higher quality, it can just be squeezed more before it blows up. Higher compression engines need to run higher-octane fuel so it doesn't combust prematurely. That said, modern fuel-injected engines are able to detect and compensate for fuel that is lower octane than recommended - meaning you can run 87 without a problem.

EDIT: And to answer your question, lower octane fuel is carried because most vehicles run on engines with low compression ratios, which actually run better on 87 than 91. If you put a high octane fuel in a low compression engine, it won't fully combust and you'll have fresh gasoline going out the exhaust.

 

I always run the highest octane that I can get. Anything below 91 and my box stock 2002 Ultra pings like hell. I had a '97 stock Ultra with an Evolution, and it was exactly the same way. .................Must be getting too much fuel in my water or something.

 

Same here.

 

Uhhhh, E85 is 85% Ethanol and 15% gas. That would be a DEFINITE "no".

 

Oh, I just gotta see what comes of this.