Resurrecting my '79 KZ1300 from a 28-year nap

I also have a copy of the wiring harness on a wall. As kawboy pointed out; The convenience of this when diagnosing/sorting out wiring issues is much easier then trying to keep the manual open while perching it somewhere close, when your hands are full of meters, leads and that glass of Scotch !
When laminated, a felt pen can be used to highlight the circuit being tested. When done, wipe it clean and it's ready for the next time it's needed.

Poked around a bit at lunch....

Removed the tail cowl and found that ground connection where the L,R, and Tail light grounds join the main black/yellow ground wire.
Metered from there to battery negative, same results. Dead short with the key off, 500ish ohms with the key on.

Pulled the main ground cable and the black/yellow ring terminal off the battery and gave them a good brushing with sandpaper til the copper gleamed. That dropped key on resistance down to about 380 ohms, but still not good enough.

I did notice that when I remove either the Headlight or Taillight fuses, the resistance drops to about 110 ohms.

With BOTH of those fuses removed, I get a dead short to battery minus from any ground point of the harness I check.

My suspicion is my fault is somewhere in one (or both) of those circuits.

If nothing else, this bike fell into the right hands. Electrical gremlins are like trying to find a ghost but in this case Me thinks Propav8r is a Ghost Buster !!

I work for a company that manufactures nurse call systems for hospitals and assisted living facilities. Main thrust of my job is documentation and training, but I handle our beta test programs and I'm also kinda of a one-man rapid response for really hairy field troubleshooting.

Before this I was actually a low voltage technician installing fire alarms and security systems, so I've got a pretty good handle on fault tracing and meter use. For some reason I just feel like this is going to take me awhile to track down. I kinda suspect the ignition coils. They appear to be the only non-stock electrical accessory on the bike, and they're sorta questionably wired with bullet connectors.

I'm just going to have to break circuits and isolate things until I track down the problem.

Okay I need to take a step back...

Can someone please step out to their bike and see what their resistance is between a black/yellow wire in the harness and the battery negative is, both with the ignition on and with it off?

I'm such a fucking moron.

You can't measure resistance with voltage on the system.

Classic propav8r overthinking