Topic: Electric starter toggle switch melting

[Bulldog1974]

Hello, I have a modified bike. 1974 Cb750 K Four. The starter toggle switch is down near the left side cover. It was a 60 amp toggle switch. That's what it had when I got it.

I had a problem. It was hot when I tried to start it. (Should have used kick starter) The click sound from on to off stopped, and then the positive wire burned through, creating smoke. The positive post melted from the toggle switch causing the burning of the wire to stop.

I put a new toggle switch on. Clicked it to start it. It cranked over, but a little puff of smoke came out also. Not good. What can I replace this with? It has one hot wire going to the positive side of the  battery,  and a black wire that I is going to the starter inside the bike. I assume that is the negative wire going into the engine?

Open to suggestions. I am not good at wiring. I have seen the schematics and the cartoon wiring drawing. Not sure what any of that means. Wasn't quite sure where to post this question. Thanks

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[scottly]

The starter can draw over 100 amps, so a solenoid is used to take the load off the switch.

[Bulldog1974]

I bought one of these and will add it between the starter and the switch. Thank you for your suggestion.

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[Bodi]

Check the switch rating, a 60A @120VAC switch is drastically derated for DC use. Also, the starter motor acts as a big inductor so there will be a kickback voltage on disconnection that will arc across the opening contacts in the switch and damage them a little each time it's used. Even the DC rating on switches is for non-inductive load and a snubbing diode should always be added for inductive loads.
The solenoid relay for a starter motor has very large load contacts that still get damaged but they are so big it takes many many cycles to erode the contacts enough to cause trouble. And most can be disassembled to file a new clean surface on the contacts.