Jetting and fuel Rotax

Hello all,

Currently running a 122 jet which seemed about right for 78-85F weather in summer but now it’s 65-70F on race days. Should I be looking to move to a 125-128?

Does anyone run the canned VP fuel for Rotax or is 91-94 octane pump fuel just as good?

Thank you

98 pump gas is better, jetting witchcraft Rotax dudes will help.

You need to know density altitude to guess on any changes, not air temp. You can find it on a weather app usually. The rotax jetting app gets you pretty darn close and takes current density altitude into account.

It’s pretty common for Rotax racers to go solely by air temp, I believe some of Rotax’s recommendations are based on air temp actually. Maybe not optimal, but it seems to do the job for people. I think I have a prevo chart somewhere, I’ll see if I can find it.

If you’re running pump fuel I’d urge you to run gas ethanol free gas, sometimes called non oxygenated.

I’ll have to find a station that has this. Thank you

Shell V Power

20 char

Where are you based? If you can’t find it at a car fuel station you may be able to get some at a boat marina. If you’re in the US will help you find stations that supply it.

Lastly you could run 100LL avgas. It’s more octane than the Rotax needs but it won’t hurt it.

Yup perfect I have a shell close by

Looks like the Shell near me has middle grade ethanol free. Thanks again everyone.