My foreman is backfiring when I turn it off. Its not a loud backfire it sounds like a muffled backfire just as its turning off. Im also having problems with it idling to high after I ride for awhile. I am guessing that due to it idling high when I turn it off its causing a muffled backfire. I have turned the black screw on the carb but I cant tell a difference in idle when im turning it.