On the 16mm carb and the Tecumseh hs40 or hs50, i'm going to try some re-jetting. Turns out in the winter (which we have in michigan right now!), the 16mm slide carb doesn't like the cold weather. Wants to run with the choke on. I will try some jets and see if things change. It runs great in the summer, but not so much when it's 30 degrees F out. cfh