ive got a 2012 big red that seems to be running rich. ive owned it about a month and its got about 3000 miles on it from the previous owner. it smokes black with a touch of gray and smells rich. it mainly does this on hard acceleration after a short idle, then fades a bit. its not white or blue. ive changed the oil, plug, cleaned the air filter and even tried running with the air box open with the filter off in the shop. not sure if the air temp sensor, valves, timing, or ecm could cause it. just figure I cant be the only one that's had this trouble