When I turn on my headlights, the engine sputters and runs rough, regardless if it's on the magneto or battery.
The drivers side headlight does not work, the bulb is good as is the thimble connector. I've replaced the wiring and the drivers side has been grounded to the frame.
I have cleaned and checked all connections and wires, but I'm stumped.
I think I'd be looking the switch over.
The switch is good. I will put a full charge on battery and see if that helps the battery part of my question. The magneto connection has also been checked and cleaned.
If it does the same on mag as on battery, it almost has to be "downstream" from both. I'd check to see if there's a bare spot on one of the wires rubbing somewhere causing it to short out.
Unless it is mis-wired, there is NO way that it should do this on both mag and battery. Recheck everything! Something is cross-wired or shorted.
If it pulled the engine down on only one power source, I would suspect a short in the bulb or socket of the lamp not working. By the way, I have seen bulbs that were shorted inside.
Have you tried to put any type of amp meter on that line? I don't know if the type you clamp around the wire will work on 6 V. You could also disconnect the power source then see if the wire is grounded with a multimeter.
Seems like switch related. Is the switch original?
Could be worn so that when you turn the lamp lever, to Dim or Bright, the center key cylinder, when on Bat or Mag, turns just enough to make poor contact and may cause the symptoms.