ok so here is the prob i got a yamaha fzr 400 exup it runs ok starts ok and then pulls away and suddenly wont rev over 2000 rpm if i do get it to rev over 2000 it clears fine, i have checked the exup valve was a bit sticking so sorted tht but still the same prob any help pleaaseee

i had it with my XJ 600 where it would not rev over 7500 rpm. changed the fule filter and cleaned out the carbs and it was fine