I would like to get smaller Domes for my Banshee and I still would like to run pump gas.
I have 22cc Domes now

 

What altitude do you intend to ride? From what I have been told, once the cylinder pressure gets above 150 psi you should consider running racing fuel. I think (not sure)Pro Design has a web site that lists the psi at specific altitudes for each size of dome that they offer. If not, I'm sure that their tech's could answer your question. I currently run 19cc domes and produce 150 psi here in Phoenix (roughly 1,600 ft. alt.) I run 100% race fuel. I was told that I might get by with a 50/50 mix but that 100% race fuel will run cooler. Also, I primarily run at Glamis where the cylinder pressure will increase to about 180 psi. Definately need race fuel there.

 

The altitude is below 3000

 

Also if you can get a hold of a rockymountainatv
catalog, it has a complete chart of the PSI/elevation/dome size configuration one might have. Go to www.rockymountainatv.com and order it online if you don't have it....

 

I've tried them all. You probably will be able to get by with 21cc domes w/ pump premium. I use 19cc domes with 50/50 mix of pump & race fuel, and it rocks! Tried 18cc domes also and was not satisfied with top-end and over rev ability. These are to compensate for higher altitude and add more low-end torque. Bust out some cash and use at least a mixture of partial race fuel...it's worth it.