uh? i have a 4mm stroker 5 mm long rod hot rod crank, 795 series 64.5mm piston, 2mm 21 cc cut dome, port matched all by F.A.S.T racing and 4degree timing advance and i dont have any trouble the shee ran really great but a spark plug came lose ont the right dome
i ran 21cc with my stock stroke engine and +4 timing with 91 gas pump but im on the first rides on the 4mm stroker and a spark plug came out of a dome
we dont have 93 gas here 91 max