What mpg do you get?
 

My 600f3 is only getting about 40, I was told this is low. I am using premium, which I"m told you're supposed to use regular, but the regular has ethanol, and I thought that was bad for the rubber.

believe it or not 87 regular is what the manual says, though ive used premium for a long time and its been fine.
personally there is no noticeable difference cept if you burn high enough octane it can hurt the seals.

i get between 35-45 depending on how im riding. i run 87 octane and she runs like a bitch on it

Wait..i never knew this. So should i be putting regular (87) or Super/Premium (93). I just always thought it i was suppose to put the highest in my baby!

Technically 87, but isn't the 10% ethanol bad for our older bike's seals?

dont worry so much. haha i think you will be ok

Use the lowest octane gas that doesn't cause knocking / pinging. But yeah, for US octane rating its regular unleaded. The rest is a waste of pennies.

If someone tell you that you should be using race fuel, borrow his helmet and smack him with it :)

Well, I want to put a million miles on my bike, no way a Harley is going to have outdone a Honda, no how.