CB360 Hot Coil


So as the subject states I'm getting a hot coil, a very hot coil. This is a new a build and everything is new, wires, plugs, points, coils, condenser, I've had the bike running and it seemed to be fine, but of course I noticed one of the coils gets really hot.

I've noticed now as I'm finishing everything up that the coil heats up quite quickly even when the bike is not running but the key is in the on position.

Everything is wired up as shown in the attached image. The hot coil is #2.

As a test I switched the black wires coming from the coils with the opposite points connection, and of course I get a hot coil, the only thing is that its now the opposite coil #1 getting hot, not #2.

So whats going on here?

The only thing I haven't changed is the original wires going to the points, as I'm typing this I'm guessing thats whats causing me problems, a not so good connection.



Coils will definitely heat up during use. Especially so if they're on and the bike isn't running (you shouldn't do this if you can help it).

If you leave them on without the bike running you will often cook them to death. The symptoms get worse over time, which is probably what you're experiencing.

Time for new coils.


Thanks for the reply Sonreir, I never have it on for more then a minute, more or less testing lights and other electronics.

Is it odd that only one coil gets hot? And if I switch the wires the other coil gets hot?


Not super odd. It would depend on which of the coils is currently grounded by the points. Like I said though, they do heat up. Especially if the bike isn't running.

I'd keep an eye on them.


where does this go?
You can double check the point gap just in case (Only meaningful if the engine is running). Too small keeps the coil connected for longer and gives it less tome to cool off between sparks. Also make sure your coils are running on the voltage intended for them, as 12v will overheat coils intended to run on 8v. I have experienced big overheating with a few coils including high output aftermarket coils. Most times they just get hot and stop working, and then work again once cooled off. Had a boat that did that and it took a while to figure out as it worked again pretty quickly. Age certainly seems to be a factor and once they start to get way too hot they don't seem to go on for much longer. I had one coil on a bike get so hot (still running just fine) that it melted the throttle cable running past it seizing the cable and destroying it. Probably wouldn't have believed it if I had not experienced it myself! Was pretty exciting at the time!


I just left my key on for a few minutes and since I took my tank off I noticed the left coil was very hot. Is this indicative of something being just the left coil.


Well-Known Member
The coil will get hot when power is flowing through it. Remove the points cover and pry open both points with a card or plastic pointer. Then turn on the ignition and see if either coil gets hot. If it does, there is a short somewhere. It might be the points lead touching ground or perhaps a frayed lead or a dead short in a condensor.

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