Popping thru carb

Hello all, I'm new to this site, this is my first post. I have an old iron head sportster with a 38mm mikuni. My bike was running good up until 2 weeks ago. When first started it will only run with the choke on, then as it warms up the choke can be released, but then it will pop or puff intermittently thru the carb. As the engine gets hotter, it pops less and less. I've played with the low speed air/fuel mixture screw, adjusted the valves, changed the condensor, re-adjusted the points, tightened all of the intake clamps and it doesn't seem to make a difference. Could the coil be bad, it's about 15 years old. but I don't want to spend $50.-$70. and still have it popping. The spark at the points is very faint. Thanks, Fiddyfofoad

Sounds like you already know the problem... Now all ya gotta do is fix it...

I have a accel power pulse coil,I'll give you a good deal on,I just took it off when I got my electronic ignition.I have a 75 sportster.....

you might want to check your mechanical advance,I had one come apart on me,and had to push my bike 3 miles.

Thanks guys, I appreciate the input. All of the coil connections are tight, I guess I'll get a new coil and try that. The carb was disassembled and cleaned last spring so I don't think a fuel problem would pop up out of the blue. A 15 year old coil on the other hand... Thanks Fiddyfofoad

Well,well,well... what popped out of the blue? It was a fuel problem. Before springing for a new coil I figured what do I have to lose? Took the carb off and removed the bowl. You wouldn't believe the amount of crap clustered around the main jet. Disassembled it, cleaned and blew it out, runs like it used to. I wonder if the screen on the petcock came off?