I just had service on my bike and changed the cylinder, piston, bearings, "valve bearings" or what its called. because it smoked, the cylinder was no good, but now when i got a new cylinder on it still smokes. I have driven for about 30 mins with it, just to see if it was smoking because of the oil in the exhaust pipe, can it smoke for a while if there is oil in the pipe? or ? im thinking of changing the "valve bearings" again maby i forgot one? heh.