Re: 1979 jag engine bogging down need help
Mike, you need to take a good look at the wiring in the handlebars and down the steering post. It sounds like there is a short between the headlight circuit and the kill switch circuit that when you plug in the headlight acts like a kill switch.
The two systems are separate. Engine electrical is separate from lighting electrical. The two can function independant of each other... most all sleds are designed that way. You've got to have a wire shorting across the two circuits causing your problem.
Check the handlebar controls and kill switch area for any rubbed wires.