Well, took the 40 out today for the first time since the carb. rebuild. I'm getting a knocking noise while idling. The engine supposedly has 107,000 miles, but for all I know it could be 207,000. The title was mileage exempt. I've owned it for about a year and put 3,000 miles +/- on it and never heard the knocking sound before. Any ideas what it might be? I'm also noticing some smoke upon taking off from stops. Didn't notice this before the Jim C. carb rebuild, although I'm very doubtful the carb has anything to so with the smoke. I'm wondering if it is head rebuild time, or total engine overhaul time?