I agree with juice. No valves, at least regular valves on 2 strokes that will cause smoke. Some 2 strokes have reed valves and i've seen some older seventies Kawasakis which had rotary valves. But none of those valves caused smoking other than normal oil consumption which is a normal 2 stroke occurence. Just get good 2 stroke oil. Preferably, one formulated for a 2 stroke oil injection system.