Stuck on the side of the road.

Well, Saturday didn't go so well in taking my bobber (79 KZ750 twin) to a local bike show. On my way there while riding down the highway, the bike just shut down. Upon inspection of what could have caused the problem, I found that the power wire running from my battery to the starter solenoid broke the ring terminal off which, I'm assuming caused the wire to touch the outside basket of the solenoid. What I have found so far:

1. Blown headlight. Fuse was not blown.
2. No taillight but do have a brake light
3. No spark at the points
4. Engine will turn over while trying to start it but, will not start.

Is it possible that the stator, regulator, coil, or condenser could be fried? Sorry, I'm not the greatest electronics guru but, I can read a multimeter and have general knowledge of what each component does. I have looked at the wires and can't seem to find anything shorting themselves out. Any help/starting point would be greatly appreciated. Hopefully I'll have it running again before snow hits the ground.

Thanks,
Oldschoolbobber

The EXACT same thing just happened to me. I was logging on to post about it but here it is.

I have a 77 KZ750. While cruising down the highway it just stopped running. I had a short yesterday but rewired some stuff and drove it about 50 miles before this happened.

No tail or brake light. Turns over but won't start. No electrical lights but the battery is still good.

So I'm hoping that someone here has some guidance. Electrical is not my strong point either.

The old style glass fuses can look ok when actually blown. Take out of the fuse holder, clean the fuse holder terminals and test the fuses with a multimeter.

If a battery becomes unconnected while riding down the highway, the bike usually will keep running for awhile. But the regulator pulses don't get filtered by the battery anymore so the regulator loses regulation. (See below for more on why.) The result is, at highway speeds, the bike will get too much voltage. The headlight will get very hot, sometimes the glass actually melts, (not break). Most bulbs will overheat and burn out. The coil may overheat and short out. The regulator may actually get damaged. Points may get pitted heavily, and condenser may go bad.

The reason the voltage goes so high is because a voltage regulator regulates based on average voltage. Without a battery or capacitor to smooth out the alternator pulses, the RMS voltage goes very high, without necessarily having the average voltage getting very high.

Here is an overly technical explanation of the difference between average voltage and RMS voltage:
home.comcast.net/~loudgpz/GPZweb/ACvoltmeter.pdf
It is written to explain what AC voltmeters are actually telling you, but will also demonstrate why pulsed voltage has more energy than smooth DC voltage, even though the average voltage may be the same.

loudhvx,

You hit the nail on the head. So far the damage that I have found is as follows:
1. Fried Coil
2. Blown headlight (exactly as you described it with an actual hole in the glass)
3. 5 fried resistors on my led taillight board
4. Condenser meters as good
5. Haven't checked the regulator yet. Was going to buy a coil and go from there.

I'm going to order a new coil. Should I just buy a stock coil for the replacement? I'm going to do your HEI mod so I was wondering if the stock coil would be the best option? I do have mounting restrictions since the frame is custom made for the stock coil.

Thanks for the help!! You da man!

Yes, stock should be fine if you can find one. Z1enterprises sells the Emgo 4 ohm coil which basically looks like the stock one, and it's cheap. Some Kz owners are using the Emgo coils and report it works fine. I'm not 100% sure it fits exactly the same, though. If the bolt spacing is off, it won't be by much.