My bike starts immediately upon pushing the button; within a revolution or two with the choke on. It runs fine at idle (choke still on) and after 30 seconds or so, I push the choke off and the idle slows way down. At that point, the left cylinder (the one with the sooty plug) drops in and out. I can work the throttle to keep the bike running and once it is warmed up, it runs just fine, idles fine and acceleration is strong (still that sooty plug though). Is this more likely an ignition problem or a carburetor problem? I replaced the points with a Dynatek Dyna III electronic ignition, The coils are original. Plug wires and plugs are new (from Motorrad) Any thoughts?