Chain often keeps going when on idle, and sometimes quite fast. Read in the manual, and it says to adjust the carb. Of course, under Carb adjustment, it says this is a rather complex thing to do, and to bring it in to a dealer for service. Really, I don't think this old saw is worth that. Just turned my second bar over. I'm guessing it's time to start looking for a replacement. Obviously sooner rather than later...