Hello guys, my daughter’s GPX 600 R just doesn’t run cleanly in the stand gas. It was very fast at speed. From 1500 rpm it is possible to keep it warm. Even if you want to drive around 3000 rpm at low speed, it is very difficult to drive constant speed, because the gas start varies even though you don’t have one. Have already built the carburettors apart and cleaned ultrasonic. Nozzles, rubbers and adjustment according to manual. end effect. Does anyone know what that can be? mfg. Lifetime