mr12 jetting

Anyone have ideas on jetting using VP mr12?

From experience using the fuel in road racers I'll give you some tips.

The fuel runs much richer on the main than the pilot.

With u4.4 I went up 1 on the pilot and 1 on the main. Big increase in power.

With mr12 (which I haven't used in my 250f this is just advice based on my experience in road racers) I'd start with 1 up on the pilot and 2 on the main, then tune from there. Mr12 is amazing once you are tuned for it. Someday I'm going to grab 5 gallons to play with it in my 250f, I'm just not fast enough to justify it yet.

I hope someone that has actually used the fuel in a 250f chimes in as I am really curious as to how much more fuel we need using this stuff.

Hope I helped some!

a lot will also depend on what other mods you have.


just a 1 time use is kind of a waste of time.


if running it full time then really worth it.

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