Backfiring...with choke on and other carb/ignition issues???

[MrJoel]

Just need to trouble shoot this in my head (and yours if you'd let me) before I get into it tomorrow. I'm getting a backfire while on choke and it seems to miss while the throttle is steady, not while accelerating. I'm running a #20 pilot and a 102.5 mains, just headers (no mufflers).

It's obviously getting too much fuel, or the ignition is cutting out for some strange reason. I am running the autolite plugs and just picked up the NKGs to switch over after reading a bunch of negative comments on them for motorcycle use. I've ruled out my initial thought of a fuel pump or vacuum issue with the petcock as backfiring is an issue due to too much fuel.

Should I drop back down to a #17.5? It starts up right away on choke and goes from low idle to about 3 grand in about 15 seconds (usually indicating its close to warm enough to go...but not on this bike), after about 5 minutes of regular idle (no choke) it takes another 2-3 miles to not want to stall out after a stop...it's cold up in der

I'll throw up a video tomorrow on how it sounds when freshly started!