mortbike

I have tuned my VTR to run on 87 octane with 10% or less ethanol.
I have found a gas station nearby that sells 90 REC non-ethanol gas.
Will using the non-ethanol free fuel make my AFR richer or leaner? thanks-Mort

xeris

I'm sure that someone will correct me if I'm wrong.
The higher octane fuel will act like the tune is slightly richer.

VTRsurfer

Air/fuel ratio is just that... air and fuel. Ethanol is fuel.

Stevebis1

While literally true I'm assuming the question is is really asking about the affect on the carb tuning.
E90 needs a slightly lower (richer) stiocheometric ratio to work best. In most vehicles not enough to be noticeable, but in our Shawks, depending on your current state of tune and how sensitive you are, it can be.
Personally I could feel the difference, especially when I was running the K&N. With that filter I had a slight lean stumble at 2800 rpm. when filling with straight up gas that stumble would pretty much go away.
Ethanol has been a hot and disputed topic here in the past, but I'm on the side that says there is a difference.

JamieDaugherty

As mentioned, Ethanol requires more fuel to reach the proper stoichiometic levels. Normally this is only a problem for those karate-car dudes running the E85 conversions. At E10 or E15 I doubt there is enough "E" to throw off your mixture.

Bottom line - just run the non-E gas and enjoy.