i'll give u the symptoms, and u try to figure it out..

ok as u prolly know from the past posts, i gottta piped and rejetted z and for 5 months have had zero problems...i recently decided try a different jet cuz of a suggestion, but it popped and sputtered so bad after throttle it was terrible...on the throttle it was ok...now i put the old 160 main back in that was so good before, and the popping and sputtering is still there ...what have or haven't i done? i made sure all the intake clamps were tightened, i just dunno...also i dunno if i just haven't noticed or what, but at night my header glows solid red now...i dunno if it always did or not, but wouldn't think that is normal...please try to help me out here guys

 

replace your spark plug, the other jet might have caused the plug to get alot of unburnt fuel on it, its a cheap and simple thing to try and plus its always good to put in a new plug