Motorcycle Repair: backfiring, vacuum line, diaphram

Question
i have a 1996 vulcan classic 1500 at an idle it pops & backfires i changed the plugs it didnt help do u have any ideas

Answer
Hi David...

Ok... Was the bike running fine and just suddenly started backfiring for no reason? Or did the bike sit for awhile not being used? Also, have you made any alterations to the exhaust system prior to start of the backfiring? If the bike just up and started backfiring at idle for no reason, I would suspect the air cutoff diaphram in the carb(s) may have a hole in it. If this backfiring started because the bike sat unused for a while, then I would suspect you need to clean the carbs. If the backfiring began after an exhaust modification, then you need to rejet the carbs. Also... airleaks at the intake manifold(s) or a vacuum line can sometimes cause backfiring. Hope this helps ya David...

Jack