what causes burning wires

[wolfman]

I am going to rewire my bike. 83 850GL. Yesterday I started it up and after about a min, smoke started coming of the yellow wire and white/blue wire that come from the reg/rec right where they connect in to the connectors by the fuse box. Would that be a short somewhere or a bad reg/rec? That being said, the wiring is in bad shape - connectors missing tape everywhere. That is why I am just going to rewire the whole thing. I just don't want to get it all done and have a bad part burning things up.

Here is a pic to give you an idea of where I am talking about.

[chef1366]

I am going to rewire my bike. 83 850GL. Yesterday I started it up and after about a min, smoke started coming of the yellow wire and white/blue wire that come from the reg/rec right where they connect in to the connectors by the fuse box. Would that be a short somewhere or a bad reg/rec? That being said, the wiring is in bad shape - connectors missing tape everywhere. That is why I am just going to rewire the whole thing. I just don't want to get it all done and have a bad part burning things up.

Here is a pic to give you an idea of where I am talking about.

See if you can find a decent harness from Ebay. I just rewired a 1986 GS450 with an Ebay harness. It was a little cut up but do a section at a time and keep all the plugs taped off and marked. Really not to bad.
On this bike someone had bypassed the main fuse and shorted out some turn signals and turned the headlight bucket into a melted hornets nest stemming from the ignition switch. I even had to solder new wires onto the ignition switch because this bike had an oddball switch and they wanted $100 for one.

[Zooks]

Most times wires melt because of a short circuit - ie: positive going directly to earth (for most modern circuits). The wire gets hot carrying such a heavy load and the insulation melts. Eventually the copper wire itself starts to melt. This is supposed to be exactly what fuses are for. The fuse is meant to 'pop' before the wire gets hot and melts. As you have found out, on old vehicles things don't always work like they should.

[J_C]

You should test the rec/reg, but look for corrosion all along the circuit Especially within those connectors.

Don't neglect the battery wires too. Someone postd within the last few days about the positive battery wire. I cleaned the connectors off with steel wool; I couldn't beloeve the amount of corrosion in the wire where it crimps!! It was brown and green and chalky and goopy and just a plain mess. I ordered new positive and negative battery leads, but just with me doing my best to clean the connectors my charing problem seems to be much better. 14 v at idle and only dipping to 13.8 at 5000 rpms.

Only reason I bring this up is because my rec/reg leads get a little warm too. I'm hopng the new battery leads reduce the resistance in the circuit. (not too sure on whether this is scientifically a possibility ??? ) If not I'm going to trim back the wires a bit more at those connectors in hopes of reaching fresh copper

[wolfman]

I did check my rec/reg I think it is bad I am only getting 10v with the bike at 3500. Right now if I get it above that it quits until it warms up but the wires are smoking by then

[J_C]

I'm no electrical expert. Makes me curious. Why would the wires from the stator overheat if the rec/reg is blown? I would think it would create problems further "downstream" or am I misunderstanding how electricity works?

In any event, wolf do the diode checks on the rec/reg, as well as any other tests in the stator papers. Good luck!

[doctorgonzo]

If the R/R is blown the stator can hit a dead end in the circuit. Instead of the R/R working to get rid of excess voltage through charging the battery and heat the it just builds in the stator.

[wolfman]

I retested the rec/reg the way it says in the stator papers, its good. After further inspection of the wires the red/white and the green/white had bare spots further up in the wiring. Could this be the problem? I also think I have a bad ground. I have a black/White coming out of the fuse box. And for the life of my I can't figure out where it goes. It doesn't have any kind of connector to even give me a hint.

[J_C]

Black and white out of the fuse box? Mine doesnt have that.

[wolfman]

Thats why I'm baffled I can't find it on any diagram. I wondering if it has any function. It's just snipped.

[J_C]

Take the back off and see where it's soldered in. Someone may have added it.... ???

[spchips]

RR - Stator connections, the hot wire to the harness, all these overheat at connections because of voltage loss due to a dirty connection.

Imagine a system 30A red wire, that normally carries 12V. At the connector, it's losing 0.3V

0.3V x 30A = 9W of heat

This isn't much for a dash lamp, but inside a connector, it can melt things easily.

And this is just for basic functioning. If the battery is low, the current, and heat could be much higher.

[drhach]

If you can do it, take the whole harness off. Get a good schematic and go to it. I did this with mine and I found that the harness had been hacked and slashed more than I imagined. It was a lot of up front work, but it saved a lot of work chasing gremlins. This way you can verify all connections with an ohm meter, clean all connections, check for melted insulation, verify wire color, etc. In my experience, once wires start burning, they burn in obscure places tha pop up after you think you have it fixed.

[J_C]

Dr Hach, how do you measure the resistance with an ohm meter? (in other words, I assume you plug red at one end and black at the other with the ignition off, correct? Then what's a reasonable loss, versus something that needs cleaning?) Thanks!

[zehrmacht]

I did check my rec/reg I think it is bad I am only getting 10v with the bike at 3500. Right now if I get it above that it quits until it warms up but the wires are smoking by then

Sounds like something is going directly to ground. If it's producing heat and only showing 10v with a good stator then it must be drawing amps. A full ground will drop the volts and spike the amps.... remember E/I x R. If the stator is putting out full voltage but you only show 10v with smoking wires, a short to ground would explain it.