Bad Backfiring

[Chevy1500z71]

i just read through this thread, and Fred, i see how your thinking but your thinking of it wrong, the bike is giving a false lean condition from the jets being clogged, that doesn't mean its just way to lean. clean it first.

if it were my bike id clean it good, and maybe fatten it up just a little bit, but you don't have to. and backfiring wont hurt anything, asuming that its not so bad you cant even ride the bike.

[svtbolt04]

But he HAS cleaned the carb. A clogged jet will do just as much as a jet made to squirt less fuel. If he has cleaned them all with the same problem still persisting, then he is running lean. You said the bike sat for a while? Take the intake boots off and check to see if they have started to dry rot. 

His definition of bad backfire might be a few decel pops, or sounding like a fire fight in afghanistan.

[wheelie_boy]

The hot start screw is stripped and not seated to good, so i think that may be causing the backfire. took it for about an hour ride today and it seemed to backfire less as i rode it more?.? i could have just gotten used to it though.

[Chevy1500z71]

o, sorry, didnt realize he had already cleaned it. although its jetted lean from the factory, its not jetted that lean. so the only remaining cause of a false lean condition would be anything on the carb body, or intake that is leaking. iv never delt with a hotstart, its just a choke right? if it is directly connected to airflow through the carb and its behind the middle where the fuel delivery has taken place then if its striped or leaking that could very well be your problem. a riped vacuum line, or ripped intake boot also would do this.

if you suspect an area that you think is letting air into the carb (like your hotstart) take a propane torch (don't actually light it) and aim it towards the suspected leek as its running, if the bikes idle picks up then its leaking becasue it will burn the propane as it enters the leek, which will raise the idle speed.

[B. Graves]

if i were you, id take the whole intake off up to the motor. make sure everything is sealed up good. i screwed up a gasket on my old XR and had the worst backfiring you could imagine and the bike wouldnt even run right. it was cause there was air getting in after the carb. inspect all the places where it seals up at. its very easy to get one of those on just a tad wrong and cause this too.