possible carburator problem???

so, i can fire my bike up but it dies soon afterward.  i put in new plugs and it looked like i was running rich.  but even with the new plugs the problem was the same.  on some occations when i'm firing her up there is a pop and smoke coming from the carb.  i would love some suggestions and keep in mind, i'm no pro..just kind of learning as i go. the engine is a rev-tech 100" and i have a mikuni 44mm carb  

Make sure your ignition time spec is right on!  Pop and smoke means lean mix and/or intake leak between carb, manifold, and/or intake valve(s)!  Plugs show rich mixture, may be wrong needle, and/or jets on mid/main too fat mix?  

I struggled with a carb set up no one tried for a year, on the smaller version worked, took it apart, used the same specs in the larger carb and been running great for 30 years!  

In addition, if fire up when cold, all specs correct, Mikuni carb, meaning slide valve kind, should have enrichment lever, to compensate for fuel dribbling prevent mix with air, resut in lean mixture, pop through carb opening, until engine warms up to better vaporize fuel so more readily mix with air.