Ihave an 04 1200, its all stock except for a k&n air filter and screaming eaglepipes. It was re jetted by the local hd dealer. the problem I have is after riding it for a few minutes and it gets warned up when I come to a stopped it misses and backfires thru the carb.the longer I ride the worse it gets.its fine going thru the gears just coming to a stop.i checked the plugs and they seem to look ok. Could this be a week battery or something else electrical?