Motorcycle Repair: shovelhead electrical problem, fuel fires, key switch

Question
i have a 1981 flh with only 1000 miles on it original owner, i am having trouble keeping it running . the bike will just start and run fine and then with no warning it will just quit and not start back maybe until the next day and it runs fine again and just quits when it decides to. one thing that confuses me is when it does this you can crank it over and when you finally see it is not going to start you can cut the key off and then turn it back on and the fuel in the cylinder will fire but cranking it again it will not start and every time you turn it back on after cranking the fuel fires again. i have changed key switch , checked coil and wires running to coil, i have checked sensor plug for shorts and continuity to ground , i feel it may be ignition module or regulator. what do you think it is or what i can check.

Answer
When it wont start, do you have power at the coil hot post? If you pull a spark plug and turn the motor over do you get a spark?
When it wont start and looking down the throat of the carb, twist the throttle, as you getting gas? Turn the motor for a second with your hand over the front of the carb, is it pulling your hand inward and is it getting wet with gas? After you do that turn it over. Does it start?
Mike