Motorcycle Repair: CB750 Electrical problem, electrical issues, starter button

Question
Chris-
I have a 1978 CB750 Four (K) I just purchased. Brief history of prior owner. Everything ran and rode fine. One day while riding he notices the pushbutton start is stuck. Next day the button doesn't work to start the bike but it would kick start. Now it won't kick start or pushbutton start(Battery was dead when I got and I have replaced it).Now, When I turn the ignition on the guage lights won't stay on unless I hold the key in just the right spot. (Bad ignition switch?) I've crossed the solenoid (with a screwdriver with insulated handle) to make sure the starter turns over. It does. Also when the ignition switch is on, I've checked the blinkers and they stay lit when turned on in lieu of flashing. Any of this make sense?

Thaks for any help!
Dave

Answer
Hi Dave.

Unless the wiring harness has been replaced, then you have old wiring on that old bike.

The big thing with older bikes is that after a couple of decades, there will be electrical issues due to shorts and faultering components.  This is quite normal, much to all of our chagrin.

You definitely have an issue with the ignition switch.

You could have a major problem with the starter button or the button could just need to be cleaned.  The only way to know is to take it apart and see.  Cleaning the contacts of the switch is usually just a matter of lightly sanding the contact points with a little 1000grit sandpaper, til it is nice and shiney.

Also, you will want to check the wiring and fuses with a multimeter and look for shorts, bad fuses and bad connections.

Start with that and let me know what you find.
Good luck and ride safe.
FALCON