I have '57 panhead, just replaced plugs and points. Fires first kick then starts backfiring and running rough, won't idle. Previously would start, run a minute then die, souds like running out of gas. Float may have been stuck (linkert carb, what else?).

Too much gas? Check and see if plugs are wet.

'06 Sportster 1200cc will not start, no fire to the plugs, fuses good. Could it be the coil? How can I confirm?