i have a speedfight 50, its done a fair few miles but about 1500km ago a new airsal 70kit was fitted. it also has doppler race exhaust, uprated variator and clutch. ive been having problems for a while and cannot solve it, the bike has a good top end once going but no pulll away and looses power very easily, ive tried new belts, all light and heavy rollers and none of it seems to make a difference, ive been told to check the compression but it reaches 8bar, is there anything else you can help me with?? many thanks.

joe cook, November 2006

the problem is the race pipe alot of these exhausts do not give enough back pressure at low revs and causes the engine to lose power while the rpm is low have you jetted the carb for the big bore kit and what weight rollers have you tried

adam bike doctor, November 2006

sounds like you're set up for high power but narrow power band. try using heavier clutch springs so your powerband will be always up before launching.

kris urian, November 2006