what dome size?

[edz250r]

I'm looking to purchase a cool head. What is the lowest mm that you can run pump gas with?

[zedicus00]

21cc, 20cc MAY b o.k. if u can find 93 oct pump gas but even then i wouldnt chance it.

[Roostin250R]

I run a 21cc dome on mine with 93 pump gas, runs just fine. Go any lower and I wouldn't chance it.

[edz250r]

What is your compression with the 21cc dome? I've heard that anything over 185 requires at least a mix of race/pump gas.

[Roostin250R]

I haven't checked it lately being I recently had my engine builder freshen my top end, however I have been running this set up for several years now with no problems. My builder ( K&T Performance in Roy, Utah) told me 21cc is fine for pump gas but if you drop to say like a 19cc dome then he said you would want to run higher octane.

[stocktires]

I'm running a 19cc "Powerstar dome". Runs fine on anything actually. I'm now only putting in VP Red, 105 octane I believe.