I am having serious exhaust backfiring after approximately 15 seconds of the engine running. I rebuilt the carb (850 Demon dbl pumper) and it is still doing the same thing.

Has anyone had issues with exhaust backfiring due to the carb?

Thanks

Popping in the exhaust means fuel is getting through the engine without burning in the cylinder. Check your plugs and wires.

See if you have a leaky header/manifold.. can you
hear which side

This might not be your case,but I once had exhaust popping when I hurt an exhaust valve spring. Popped the covers and sure enough one exhaust valve was broken. I also rebuilt the carb thinking that was the problem. It might be worth checking into if other easier things to check don't show anything

If you give it gas its fine. It only backfires at an idle.

Chased this too, Carb too rich and unspent fuel blowing up in the pipes, Keeps people on their toes driving through the pit LOL. Lean your idle way out, I was at like 2 1/2 turns out, turned them in and jetted the carb down 2 sizes

It was the cap and rotor........runs like a dream now. UNREAL!!