WHAT SIZE OF DOMES?

[honda310r]

Ok so im building a 421cc cub with a 4mm and am wondering what size if domes should i run. The head i got has 18cc done in it already. Ill be Trail riding and also Duneing. Is the 18cc gonna give me to much compression? and i do run 50/50 mix of 91octane and 110 octane race fuel.

 

thanks guys

[firebanshee]

I think the 18cc will give you to much compression.A 21cc dome at sea level would give you about 180 with that set up.I would not go smaller than a 20cc.