I have a friend who hauls gasoline to gas stations for a living. He explained to me that the normal procedure is to first put ethanol in the to 10% of the tank capacity, then find out how many gallons you are delivering and fill the tank with gasoline to that level.the result, of course, is that the least ethanol you will receive in your tank is 10%, but it could be much higher. This is done because ethanol is cheaper, but the excuse is that the ethanol must be mixed into the gasoline.
The ethanol free gasoline I have purchased in various States , according to the label on the pump, has been rated at a various octanes. I have no idea why. All of it has run fine in my S4RS, as does Premium ethanol diluted gasoline , which I’ve used out of necessity. Obviously I end up burning a mixture of ethanol and non ethanol fuel. Assuming 1 gallon left when the fuel light comes on, and I add $5 worth to get me home, I’m running about 5% ethanol or less. This has still resulted in the tank swelling if not burned off quickly.
My 900SS runs noticeably better at low rpm on non ethanol fuel. At higher rpm or throttle openings, I can’t tell a lot of difference.
My SuperGlide or Hayabusa do not care what I put in them, they run fine on any premium fuel.
My 77 Bonny is susceptible to carb problems on ethanol fuel, but runs fine on it.
I use SeaFoam additive in all my motorcycles, based on the recommendation of others.