sorry i assumed it was a 125cc model ,still check the air filter though but it may also be the exhaust pipe blocked too as they do burn oil by the nature of the engine,try to loosen the exhaust slightly at the barrel until it blows a bit and see if it revs out more then .This would of course only be an elimination test and you would need to unblock it somehow i would personally cut it in two pieces and mig weld it back together once i had made sure it was clear and ok you can also just take it off an try blowing through it it should be easy to blow through with no resistance(not while its hot though)lol.
adam bike doctor, January 2010
