Hello! I did this bike a few days ago. actually ran perfectly.harley sportster 1200 custom Year of construction 1998 has a hypercharger on it etc. two in one exhaust original harley. however, the good sportsters now start to “spin” when I drive through a place, so gas lever almost not turned up, there are quite loud dull cans from the exhaust, and also from the air filter there are sounds. the gas acceptance works perfectly however. I have to confess the ic h before these problems occurred, once accidentally pulled the chuke, and that was to start it. since the engine was already warm due to longer driving, so the chuke use is not necessary.Can it be that it is due to the spark plugs? best thanks for all the infos!