Hi! I'm new here. Have 79 Sportster Carb problems. I believe it has original Keihin Carb. I just rebuilt the carb and still have problems with hard starting, backfiring, and what appears to be a flooding problem, even though I adjust the low speed mixing screw. I narrowed this down to the carb because I put new plugs, wires and ignition and check timing, back last year when the bike seemed to be running well.
Thanks for any advice.

 

Clean out the pilot jet real good and then check th soft plug (freeze plug) on top of the body right in front of the air/fuel mixture screwto make sure it is sealed good...if it leaks here the carb will not run smoothlyor at all in some cases.