Quote: I'll swap coil input wires and see if the banging goes to the left carb, and if it does, I'll know it's ignition, and if not, it's the carb.
I disagree with your logic. First you must switch input and output wires from coils (primary and secondary). Not just the input ones. If the problem switches sides, it's a coil failing. If not it's probably the CDI unit, LH spark plug or the LH carb or intake (since you haven't determined if it is electrical or fuel related yet) ...
