Can watch battery die...

Many of you know I am working out the electrical kinks on my 76 KZ400 but yesterday stumped me.

I got a new battery wire set because my old one was "crunchy." I thought this would give me a good clean setup to work with. So I hooked the wires and battery up, and turned my ignition to ON. First, just turning the ignition drew almost 1V off the freshly charged battery. Then I hit the starter button and the motor tried to turn but didnt start, did that two more times, and the battery was died at 6V and the starter would just click and not turn over.

So I re-charged the battery back to 12V, hooked everything back up, and just put my voltmeter on it. I could watch it drop from 12V to about 8V within a minute. I disconnected some things, checked for shorts, and couldn't see anything off the bat.

Any thoughts on what would be dropping it like that?

Try simply disconnecting the rectifier and or regulator/rectifier and check for voltage drop.Rectifier/regulator is designed to put voltake back to ground when voltage gets too high.
When one is damaged, sometimes it tries to put your voltage back to ground even when its not too high.
Your doing fine, take each peice away from the system until the drop goes away.
Have to checked for voltage loss with key off as well?