weird charging problem?!

Hi, Got a 1978 B2 KZ650.

When I measure the V at the battery with the bike at 4000RPMs, I get less voltage (12.2) than when I run the bike at 2200RPM (12.4). Now as far as I understand it, at about 3500 to 4000RPM, the V is supposed to be about 14V for a properly functioning charging system. Granted I am well below that but why would the bike charge higher at lower RPMs?

I got a new RR, a new battery and have inspected the wiring for any obvious shorts.

Thanks for any comments.

I usually work in a source-first way to make sure everything is working right.

What is your voltage between any two of the stator output lines? You should measure VAC and it should be ~60VAC at 4000 rpm when you measure the voltage between any two of the three yellow lines. That will tell you if the generator is producing anything to charge the battery in the first place.

Actually, on a 78 there are only 2 wires coming off the stator. This system has and combination rectifier-regulator.
If you have a manual just follow the diagnostic path they give. It will find the problem for you. If you don't have a manual let us know, there is a copy of the diagnose on the site, it was just put up a month or so ago.
Ride safe.