Charging system issues UPDATE (still need a cure)

OK I reported earlier that I had a 1977 KZ650B1 model that was cranking out the volts! I have a new rectifier, new regulator and a new battery. At 4,000 rpm I was putting out 16+ volts on my multimeter (I saw 17.0 on one test run!)

Now then... if I DON'T turn the headlight switch ON, the readings stay within the given range (14V - 15V at 1,600 rpms and at 4,000 rpms). If I DO run the headlight by turning the switch ON, the readings just keep going up past 15V when I give it revs.

Okay, something with the headlight? I pulled the headlight assembly (I have a Candlepower halogen headlamp with a 55W/60W H4 bulb), that all looked good. No blown bulbs anywhere, either. Or fried wiring. Or a battery boiling dry.

I've logged almost 2,000 miles on this bike since spring and honestly I don't know if this has been an ongoing issue ... only reason I've run across it is I was taking some readings to see if I could power an electric vest.

I'm stumped. I've tested my rec/reg units they are OK. Where to next, all?

sounds funny. Check all the connections once more. that all wires are connected right. If your system is not charging while in use, it may be your stator coil. The stator acts as a generator while the bike is running and it charges the bike. There are directions in yoru manual for testing.
I'd check your connections first though.

The simple answer is that if your voltage is going crazy your voltage regulator is not operating correctly.

Of course I'm no expert, I can't even get my bike to put out >11.5V. Anyhow, take another look at the regulator, make sure that the ground is good if you haven't already. In fact, even if it looks good, re-ground it.

I've had to reground the Voltage Regulator on all my Kz's, sometimes twice.

OK checking some connections:

The previous owner had a Windjammer on this bike and did some, uh, unique work. I was tracing all the wiring and found on the right side of the bike a black wire, a yellow wire and a brown wire that he has cut and crimped together under a big glob of electrical tape. I don't know where they go. I checked my rectifier and regulator hookups, they all are connected to matching color wires for the harness. Everything on this bike works like it should, what the heck are these wires for?

The symptoms you describe are what would be expected with a voltage loss as I described in the other thread you started.

If the problem was the regulator, it wouldn't be affected by the lights. When you run the lights, you draw more current through the "bad connection" I mentioned in the other thread. When the current goes up, the voltage drop gets worse. The regulator tries to correct for the voltage drop by increasing output. This puts a higher voltage on the battery. The battery has higher voltage, but the extra voltage is lost through the bad connection before it gets to the regulator.

Please follow my steps in the other thread.