I noticed a burnt wire on my voltage regulator. Can I just clean it up and tape it or would it be best to track down a replacement or investigate a cause of the melted insulation? They are $84 at Rock Auto. 

The braided hoses in the background are to my oil cooler in case you are wondering.

That's the ground wire for the VR. It shouldn't be carrying a lot of current to begin with. I have a replacement in the box that I bought from BlackDragon (Victoria British) a long time ago. Let me see if I can find it. Meanwhile, I suggest you test resistance to ground on the engine side of the harness where that wire connected to.

Frankly what catches my eye is that loose green wire.

For right now, I soldered a new ground wire. What confuses me is that the box is attached to the fender by two screws. Shouldn't this ground the box? I also smeared some dielectric grease (a.k.a. turn signal fluid) on the exposed components on the open side of the regulator.

Good point about checking resistance. 

Fried random ground wires are often caused by bad ground connections to the frame and battery. Current will find a path if you don’t have a low resistance path where you intend. Imagine starter level current that can’t use the battery cable but uses that ground wire instead.   ZZZZZZZ

Start with the fat black negative battery cable inspection and cleanup (both ends) and the body ground between the battery and the firewall. Then the engine harness ground screw on the frame across from the starter. Then the ground connection on the back of the alternator.

 

The voltage regulator (engine side) to ground is 0.2 ohms so that seems fine. A few months back, I had a battery cable connector crack giving me a intermittent connection. That may of resulted in high enough resistance to melt the wire. Hopefully, nothing else was impacted. 

I would just pull the regulator out and replace the burned-up wire if you have it working again. Is it working now? You should also examine the plug connectors, look for corrosion. clean it up with a small spiral metal brush and some de-oxit electrical cleaner. 

Edited July 3, 2024Jul 3 by Dave WM