rotax fuel notes
Despite its use in international competition now, the original intent of the Rotax Max was as a club racing motor. With that in mind, the motor was designed specifically to run on 91 or 93 octane pump gas. Low compression and retarded timing mean detonation risk is very low, so high octane racing fuel is not necessary. Plus, they run faster on pump gas with ethanol. Any time a club allows you to run pump gas for Rotax, we always recommend you do so. Rotaxes just run faster on pump gas. Lower octane fuel ignites faster, and has the effect of (slightly) advancing your timing. PLEASE NOTE: when you run pump gas with ethanol, you need to go up one jet. Ethanol = oxygen, and more oxygen needs more fuel. If you are concerned about ethanol ruining your engine or carb, don't be, just drain your carb bowl at the end of the day. If you stay after your carb like you should (regardless of fuel), you won't have a problem. Race gas gets foul just like pump gas if you let it sit in your carb.