My bike has been backfiring one time through the exhaust. It only happens when I start it after the bike is warm and has been ridden. It happened last season too but since then I've swapped the carb for a brand new CV w/48 slow jet, screaming eagle air cleaner and some drag pipes. I figured after all that it wouldn't happen but sure enough took it out today and it happened again. Anyone experience this before?? Any suggestions?? On the upside, the bike runs and sounds great! BTW it's a '97 FXSTC.

 

Oops. Misread the post.
Unburnt fuel in the in the exhaust port would be my guess.

 

Mine does the same thing. Really gets attention at the gas station.

Tiny

 

Same here. I'm pretty sure I'm running a bit rich, but haven't chased it down yet. Probably related.

Isn't a 48 slow a little big for a stage one?

 

Happens to me too I didn't think it was a big deal but what do I know

 

I've understood that Harley designed some ignition systems to not actually send a spark as soon as the engine is turned over. If I remember, it is suposed to turn over about 3-4 times before spark. With a carb (hot starting), most of us wick the throttle once or start to roll it as we push the starter button. This sends fuel that isn't burned right away into and then out of the combustion chamber. Then when it does fire, it also ignites the unburnt fuel. There is your back fire.
I havent wrenched on anything later than a 93 and I have stated all this off what I've heard other folks talk about.
Hopefully someone with more knowledge can shed more light or correct me if I'm wrong!!
jim

 

Tight pushrod or ignition setting.

 

that's exactly what seems to be happening. I get an immediate spark as soon as the engine starts to turn over.