My buddys 97 yz125 with 144 kit has a un-normal bog/studder at low end, and we just cant seem to figure it out carb is spotless compression is 175psi powervalve is working properly running 40-1 premix gas good spark stator is fine fires first kick, just cant get any power out of it unless the bike is absolutly screaming, i know someone is gunna say (its just a 2 stroke) but my rm125 with the same 144 kit is a night and day difference, any ideas?