Reply To: GT125 2003 Performance Issues
GT125Hi,
One further clean of the carbs and the bike runs fine without the airbox fitted. Revs well, idles well and response is snappy. I fitted the upgraded K&N filter plus jets and all good without the airbox fitted so filter not being used at this point. Fitted airbox and it will idle and rev but not so well. Will sometimes die after hard revving. Sometimes the revs take a few  seconds to drop.  All the connections between manifolds and carbs and carbs to airbox are all tight. If I remove the air filter it seems  to idle better. After a few revs it starts to increase revs on its own.
I did notice that the rear cylinder took much longer to warm up than the front one.
I don’t know where to go from here. Totally lost and a bit fed up.