Coil wire getting hot

I' m working with a 1976 900 LTD with a wiring harness from a 1979 1000cc ( I don't know if it was an LTD). Problem is the coil feed wire ( yellow with red stripe) is heating as is the red wire from the ignition switch coming from kill switch/start button. Using the Dyno coil setup. Any solutions for resolving this? Thanks.

The coils are drawing more amps then the wire can supply without over heating.
Either the coil loop has shorted or the coils need a larger wire.
Check if coils are same temperature or differ.

Check the scotch lock connection from the red wire of dyna pick ups, to the yellow with red. It could be a bad connection. Check voltage at the coil positive where the yellow/red connects. The dyna s are power hogs. Could also be in the ignition switch. The solder connections go bad

Check to see that the coils have the proper input resistance and (assuming resistance is correct) if the coil input is shorting to ground via the coil's iron core laminations.

Not sure what model you have but this will help you test the coil for proper ohms

Thank you for all the input. To follow up someone had previously repaired the handlebar kill switch with JB Weld which I believe has a lot of graphite in it. As it deteriorated the powdered JB Weld shorted the wires in the kill switch. Have repaired again with JB Weld clear epoxy.

JB weld should not be conductive.
screenshot via www.jbweld.com/faqs

Whatever it was I can only surmise. Grey epoxy like material deteriorated to the degree it was causing a short. Whatever it was is now gone and no more short.

are you still having issues with the coil wire getting hot?

No. Wire heating problem is gone.

I've attached a picture of the inside lower half of the kill switch. Left side of the round disc that supports the brown and yellow/red kill switch wires show evidence of damage repair and partial remains of whatever substance was used to repair it. This repair substance had deteriorated and become powdery, apparently causing the short.

However.

There could be an alternative or additional cause or factor contributing to the kill switch short circuit.

For those of you who have yet to experience the joy of disassembling and reassembling these kill/run switches, they contain 3 tiny springs with a tiny ball bearing atop each one. Is it possible that after 44 years one of these little ball bearings deteriorated to the degree that its rust or flakes contaminated the switch internally, creating the short?

Or, did the previous party who repaired the broken disc not reassemble it correctly and one escaped its detent position, causing the short? Because I found only two when it came apart. But, they are tiny so it could have gotten away upon dissambly.

I'd suggest to anyone taking one of these apart, do it inside a plastic bag. if the springs or balls drop out they're contained in the bag.

Btw. These little ball bearings you can get at a good hardware store.

No. Wire heating problem is gone.

I've attached a picture of the inside lower half of the kill switch. Left side of the round disc that supports the brown and yellow/red kill switch wires show evidence of damage repair and partial remains of whatever substance was used to repair it. This repair substance had deteriorated and become powdery, apparently causing the short.

However.

There could be an alternative or additional cause or factor contributing to the kill switch short circuit.

For those of you who have yet to experience the joy of disassembling and reassembling these kill/run switches, they contain 3 tiny springs with a tiny ball bearing atop each one. Is it possible that after 44 years one of these little ball bearings deteriorated to the degree that its rust or flakes contaminated the switch internally, creating the short?

Or, did the previous party who repaired the broken disc not reassemble it correctly and one escaped its detent position, causing the short? Because I found only two when it came apart. But, they are tiny so it could have gotten away upon dissambly.

I'd suggest to anyone taking one of these apart, do it inside a plastic bag. if the springs or balls drop out they're contained in the bag.

Btw. These little ball bearings you can get at a good hardware store.

Good job!!!