79 KZ400ltd rectifier/regulator mystery wire

Hey guys,

I have the aforementioned bike which ran fine until I tried to commute to work today and the bike may have caught on fire (as per the person in traffic behind me).

It was smoking when I stopped so I pulled off the Left side cover and found the pictures below.




I wrapped the offending wire in electrical tape, tried my best to tape the parts of the other wire together, and luckily made it home without a recurrence of the fire.

So I know I need a new rectifier for the bike which I plan on buying tomorrow, but my question is where/what is this mystery wire?
I saw in another post it has to do with the starter solenoid, but where is it supposed to go? Is it something I melted off the bike on my ride today? (sorry for how dirty the bike is underneath)

Thanks!

The KZ400.com site has a manual & 400-H1 Ltd supplement w wiring diagram.
When the reg/rec fried, the red/white wire probably separated from it.

In the wiring diagram there is a red/white power wire that originates at the reg/rec. The diagram shows it going to a double-bullet connector. From there one r/w goes to the battery pos (+) terminal and another r/w goes to the main fuse box & is for the 20A main fuse.

In the 1st photo the double-bullet is visible, as is the broken r/w wire at the bottom. The r/w to the right of the double-bullet goes to either the main fuse box or the battery. The single r/w on the far end of the double-buttet is either for the battery or fuse box. It's possible the single bullet wire goes to the starter solenoid, instead of to the battery ---- trace it & report back. The starter solenoid is to the left of the double bullet.

So looking at the wiring diagram and my bike, I was able to trace the R/W wires from the double bullet to the fuse box/battery and the single to the starter solenoid.

I was looking at different rectifiers online, do you think this one would work?
www.regulatorrectifier.com/catalog/1978-...-Regulator-Rectifier

I looked at the Oregon site and couldn't figure out if any of theirs would work.
Also is there any danger in continuing to ride the bike to work and back (~10m, 8mi ride) if I tape the r/w wire so it doesn't contact the rectifier and cause a fire?

Thanks for the help!

I would contact the folks at Oregon (sales@OregonMotorcycleParts.com). When I bought my rectifier from them I found them extremely knowledgeable and helpful. Ed

Also is there any danger in continuing to ride the bike to work and back (~10m, 8mi ride) if I tape the r/w wire so it doesn't contact the rectifier and cause a fire?

20 mile work communte, I guess somewhere between 30 mins and an hour's riding. It seems you have a YB12 battery, same as the 550/650/750...thats 12 amp hours capacity. Thinking a 4 amp current drain gives you 3 hours -assuming you don't have the lights on. In reality call it half that allowing for battery aging, and the ignitions like a full 12.5 Volts plus . or they can misfire.

So yes I say you'll be ok, if in doubt bring a charger and recharge in your lunch break.

Update: rode the bike to and from work with no problem. I approximated the wires and the bike ran just fine, no fires, no shorts.
I just got the rectifier I linked above and it works great. I just need to get some longer bolts to bolt it onto the bike and I'm back in business. Thanks for the help guys!

Now that's one of the better Cafe mods I've seen. It doesn't hurt the eyes.
Steve