4 mil stock cylinder in a black label frame. anybody who has seen this bike knows it has the best of everything. been in several sand shows and a couple of magazines. runs comsistent 4.30's with low 1.50s 60' on gas. ran consistent 4.1's with mid 1.40 60' the one day we tried on alky(pretty sure will run 4.0s but didnt have time to dial) please pm or email me at atvfanatics@hotmail.com if interested