hi i have a speedfight 2 100cc it starts first time every time but when i rev it. it will only rev half way and barly move the wheel i have looked at the clucth and the shoes have still got loads of pad the belt is tight i havent looked at the rollers yet but i dont think thay will stop it revving there is a 83 jet init but no air box have any one got any idea wots up with it? :S

Ashley u, March 2010

why nis the airbox not on it?and does it sound like its low on fuel ,when you open the throttle up half way does it run ok and then when you open it up all the way does it die down of make no difference/it may well be the exhasut blocked either with burnt oil or a baffle has come loose and is blocking the air flow or even the reed valve petals cracked .does it run any better with the air box on?it should be on to clean the air and offer some restriction to the air flow to get the fuelling right,have you kept the standard main jet size?

adam bike doctor, March 2010