I'm asking here because this site is much more active than the yfz site and I also own a banshee. Anyway, I picked up a yfz450 non running as a project. I cleaned the carb and gas tank/lines and it started right up. I got it to idle fine but once I hit the throttle it backfires bad. It has bill ballance pipe, k&n filter and it has been ported. Right now it has a 165 keihin main jet. Can someone suggest where I should go from here? Thanks