I'm having trouble telling exactly what color the smoke is. It is light brown and seems to vaporize like water and not linger like oil. But I don't have any coolant in the motor yet. (I did not run it long enough to get hot, or even very warm). Thanks for any ideas. I guess I'll take a look at the spark plugs. It is a used motor and I just got it going. The smoke has started after a couple days of getting it going. It was cold when the smoke started and increases a lot with more pedal.