81 KZ750 Regulator/Rectifier Wiring

First time poster here… wiring a KZ750E2 motor on a 78 KZ650B frame/harness and have run into an issue with the R/R wiring. I have an aftermarket R/R with 6 wires total - 3 yellow, 1 black, 1 red/wht, and 1 brown. Based on the wiring diagram, I have the red/wht going to the hot side of the starter solenoid. For some reason, when I connect the battery, the brown is hot - basically full battery voltage. Hoping someone can advise on what might be causing this. Thks!

How about contacting the manufacturer of the aftermarket R/R, and asking them how to wire it?  Typically, the brown wire is a voltage sense wire, attached to a switched power source.  

Question, where are you testing the brown wire for voltage? Is it connected to the rest of the loom or not connected to anything but still showing battery voltage? As I understand it on the 650 loom the brown wire caries power to most of the system once the key switch is turned to on. The regulator uses this as a sense wire to determine what it needs to do, how much to pass on to the electrical system/battery and how much to shunt as it is not currently needed. So as I said above, if the brown wire on your need RR is not hooked up to anything and you get full battery on it them something else is going on. If it is hooked up to a brown wire on the loom and the key switch is off then something else is wrong. If the key switch is on and the brown wire from the RR is connected to brown on the loom it should be at battery voltage.

Good idea. Looking into that now…

AFAIK the 77/78 KZ650 R/R wiring loom has an one or three phase stator with a field coil magnet wiring (no permanent magnet rotor).
Please check your stock main electric wiring enviroment first.


 

To the best of my knowledge the field coil system was only offered on the 77 model year 650. In 78 it changed to a single phase permanent mag system. The 750 motor came stock with a 3 phase permanent mag system. Now something I did not mention is the bike in question may have a build date of 78 but still be a 77 model year He is using a 3 phase RR system which unless it was intended to be used on a 3 phase field coil system should work correctly with the 750 motor setup..