DESCRIPTION OF THE BIKE: WIRING IS SIMPLE AND STUPID- 1973 IRONHEAD-KICK ONLY-HEADLIGHT AND TAIL LIGHT ONLY-ONE CLICK IGNITION ONLY-TWO CLICKS IGNITION AND ACCESSORY

Alright, I'll add to the million Ironhead wiring questions/disasters.

I just bought back my first Harley (1973 XLCH) from one of my buddies. For some reason he thought it would be good idea to wire in a toggle switch into the headlight to toggle on and off the headlight. Needless to say, he wired it in incorrectly and it killed the electrical system and smoke came out of the headlight shortly after riding it for the first time after the modification.

I just got the bike back two days ago. I replaced the battery (old one wouldn't hold charge) and hooked it up. Tail light comes on and I believe one half of the circuit breakers that are connected by a brass piece keeps resetting itself (with a click). It kills the entire system when it clicks, turn the bike back on and it does it again after being on for a couple seconds (it'll even click moments after being shut off). I've been chasing wires since last night to see where the short/problem is. I even wired in a 15amp fuse to replace the defective CB and came to the conclusion that the accessory wiring (brake/headlight) is shorting out somewhere because it keeps blowing the fuse. I removed the headlight from the wiring, and the fuse was great, so I assumed the short was in the headlight; however when I press the rear brake the fuse busts as well. Basically, I'm confused as hell what it could be. Any thoughts or advice on what to do?

Also:
-Thinking of replacing all of the circuit breakers with fuses instead...good idea? and do i wire the fuses exactly as the circuit breakers are wired?
-How many fuses should I have? Also where should they be?
-Generator was checked two months ago and it tested fine, and when revving the engine, it does charge the system. The bike has killed two batteries though now in the past two years. What could be happening there?

 

In your electrical system each circuit breaker will feed several circuits that are in parallel.

In each of these circuits you will have one or more components, a headlight, tail light etc.

In a circuit, the resistance of the component controls the current flow.

A short is when the current finds a path back to ground before it reaches the component (that is why removing the headlight does not help you find the short).

Since this shorted path has no resistance, the amount of current flowing in the circuit will be high enough to trip the breaker.

You have a bare wire touching ground somewhere.

You say the circuit breaker trips when the rear brake is applied, so the first place you should look for a short is between the brake light switch and the rear brake light, probably under the fender.

 

Find out for sure which one of the two circuit breakers is tripping. Either hold your finger on one at a time and feel it click, or disconnect the wire that's connected to the output (silver post of the CB) of those two circuit breakers one at a time and see which circuit has the short. Then follow only the wires from the bad CB until you find the problem.


That's the circuit breaker resetting itself after you turn off the power and eliminate the excessive current flow through the shorted wire. That's the beauty of circuit breakers as compared to fuses. It doesn't sound like your circuit breaker was bad, which was proved by your fuse blowing when you installed it in place of the CB.



It's a good idea if don't mind buying boxes of fuses when you have problems with your wiring, like you do now. If you keep your circuit breakers, if there's a problem, they'll trip, then reset themselves after you turn the power off. No money needed to do a lot of troubleshooting. Either fuses or circuit breakers will protect the wiring from burning up if there's a short. That's their job.

What's the charging voltage when things are working OK? If you take a volt meter and measure the voltage between the battery + and - terminals with the bike running at a fast idle or higher, it should read around 14 volts, plus or minus a little. If it's a lot higher than that, it'll cook the battery to death. One thing you can check is to make sure the battery cables on both terminals aren't corroded inside the plastic sheathing. A few years ago, the negative battery cable on my '82 looked good on the outside, but when I was replacing the battery, the cable end pulled right off the cable. I found the copper wires inside to be totally corroded. I fixed that and haven't had a charging system problem since, and that was in 2003. Another thing to check would be to make sure the voltage regulator is grounded well. Some regulators ground through the case and mounting bolts, others have a separate ground wire that needs to be connected to a good ground.