melting wires

Ok I just got a 79 kz650B.i hope I’m not too long winded here. When I first went to look at it the battery was dead so the guy charged it over night. Then next day I took the bike for a 3 or 4 mile run no problems. So I took it home. Then next day I noticed the battery was dead. I bought a new one charged it overnight and put it in the bike. It started right up and i did about a 15 mile ride. As I was coming home I noticed that the blinkers and head light was dim so I checked the battery and charging system I was getting 13 volts at the battery. i then removed the tank to replace the fuel line and noticed a blue wire disconnected. I connected this and replaced the tank. I started the bike checked the battery still charging at 13 volts. I get on then the main fuse blows. I remove the tank and start looking for a short I found one wire that the protective covering had a hole in it and might have had been shorting out I fixed that. Get everything put back on and turned the key. My headlight does not come on. I have a light switch with 3 settings off, PO, on before this switch did nothing now I could turn the head light off. I start the bike and let it warm up for 2 or 3 minutes then I noticed the smell of burning wires. I shut down and start looking I found that the wires by the flasher unit and voltage regulator were hot and had started to melt (see pic) the 3 yellow wires were also hot to the touch I think these are coming from the rectifier not sure. any ideas what might be wrong I’m running after market coils and ignition (see pics) please help

here is the picture of my coils

coil pic

Hey 1stkz650,
Welcome to this wonderful place. I don't have any magic cure answers to this one. Sounds to me like you will need to get ahold of the wiring diagram (which is probably available under the KZ Information tab of this web site) and then methodically figure out the problem. Sounds to me like something wierd is going on with your charging circuit. Personaly, I'd start there. Step by step, one wire, circuit at a time hopefully will lead you to discover the culprit(s) to this dilemma. There are lots of people with 650 experience on this site. So, if you have questions about how to check specific things and such, first try the forum search. Highly likely that it has been posted before. Or, just ask away.
On my 78 kz650 the two blue wires underneath the tank are for a gas gauge that is not on the USA version. So, connecting them, not connecting them doesn't matter. They are not used, unless you have a sensor thingy installed in your gas tank. I don't.

Best of luck to you. Welcome aboard!

Terry!

Check the wiring diagram real close and make sure
your voltage regulator is hooked up correctly.
I just went through the same thing on a Z1 900,
the yellow wires, where the coil power wires split,
were getting so hot they were melting and frying
the ignition. On this one the Rectifier was not
even hooked and the Voltage Regulator wasn't hooked
up right, who knows how many volts the system was
getting.

Do you have a separate regulator and rectifier or are they combined into a regulator/rectifier? It appears that the wire that is burned is the MAIN out from a reg/rec or the regulator that goes to the battery. The connection to the battery will be via the POS lug on the starter solenoid where the POS battery cable connects I think or perhaps it is spliced into the cable where the cable goes to the POS lead on the battery. In any case, I suspect a bad regulator or reg/rec. This gizmo should have 3 yellow wires connecting it to the alternator which are carrying AC to it. A brown wire will be connected to switched DC which is the feedback wire that tells the reg or reg/rec how much voltage to kick out and a black wire or black/yellow ground. Make sure the wires are secure and connected properly. Test the regulator or reg/rec by measuring voltage at idle... should be 12.5 VDC and then at 4K rpm where it should be nominally 14.5 VDC. Use a multimeter in VDC scale with leads on the battery terminals.

Same thing happened to me and my 650 the day after I got it to start, it fried wires pretty badly. What happened to mine was that when I hooked up the new battery the rectifier gave out and smoked up a bit, and when I ran the bike for about five minutes it caused heat to melt the wires pretty far up into the wiring harness. The connections were pretty corroded at the rectifier also and I think that may have contributed to the problem.

What I did was re-wire the entire bike and replace the rectifier, now it's good as new.

Hope this helps. Re-wiring wasn't too fun, but now it's all brand spankin new

If your reg/rec is still good, replace the burnt wires and clean all the connections and you should be good, but make sure that the melted wire didn't fuse with other wires within the harness, that's no fun.

77Davo650 wrote:

What I did was re-wire the entire bike and replace the rectifier, now it's good as new.

Hope this helps. Re-wiring wasn't too fun, but now it's all brand spankin new

If your reg/rec is still good, replace the burnt wires and clean all the connections and you should be good, but make sure that the melted wire didn't fuse with other wires within the harness, that's no fun.

I have a ?? What kind of wire did you use? I mean did you use the generic autoparts wire or did you find the stuff that was striped kind of like the OEM? I want to rewire my 650 and upgrade the whole harness

thanks for all the advice. i have both a rectifier and a voltage regulator. as all the wires that were getting hot came from the rectifier i decided to replace it. i got one from a bike scrap yard for $10.00 it was a little diffrent but all the wires were the same. i swapped it out and the bike seems to run fine. i get 14 volts from the rectifier the white wire + and the black wire - but i'm still only getting 12.5 to 13 volts at the battery terminals. the wiring does not get hot but the rectifier does am i ok with this or do i need to check other items
thanks