R ruicunha Member Feb 28, 2024 #1 i have a gx390 with a race prepared head, i managed to find a cheap new 420cc engine, that i think has a 90mm piston, will the gx390 head fit the 420cc engine? thanks.
i have a gx390 with a race prepared head, i managed to find a cheap new 420cc engine, that i think has a 90mm piston, will the gx390 head fit the 420cc engine? thanks.
