Excessive smoke is because it's too rich. Be it too much fuel, possibly because of the choke not closing, or too much oil, possibly because of the injection pump not closing fully when the throttle is closed. Ours had both of those problems. When you'd close the throttle the wheel on the pump wasn't returning all the way due to mud and rust in there. Ours was like a mosquito fogger at times. It would only start if you held the throttle open when it was hot. If I were you I'd take a close look at the choke plunger and cable, it should be very easy to flip the lever up at the bars and it should snap back down freely. Also pull the little plastic cover off the pump and make sure the wheel pulls the cable back when the throttle is close, if it doesn't move freely it can hang up and hold the pump open too far for the throttle position making the oil mix too rich.