just a bit of advice, your zip might have the original jet. and a brass plate in the air inlet on the carb. take the plate out and put a new main jet (approx 60) in its place. mine was a 53 when I got it and with the standard exhaust put a 58 in. certainly made a difference. with a new exhaust I use a 68, with the air screw at 3/4 turn out.