CJ750 toolbox
Installing a Niehoff WA 709 regulator in a 12 volt Chang by Richard Cook

Other folks had really done all the research on this and I referred to the articles in the toolbox. The regulator is for a '73 BMW 2002 but keep in mind there were two offered that year. One Bosch unit had an internal regulator and one an external. You want an electronic replacement for the external regulator which originally had points. I used a Niehoff since they are made in USA and are actually tested after manufacture. They are about $29 and available at Kragen as well as many other places. They should be so tough in this use that you would need to have a short and fry one to break it. The reason I’m changing my regulator is to try to pick up a bit more changing voltage. I run short trips with the headlight on all the time and after a month or so my battery needs a change. The stock regulator gave me a max of 13 volts and I’d like to get at least 13.5 or 14 out of it.
Your regulator may be located in a black box or under the fuel tank, even perhaps in the sidecar depending on the sense of humor of your builder. Color codes often mean nothing on a Chang so don’t count on that. Read all the regulator articles in the Toolbox before starting. (Click here for one of them.)
Disconnect your battery for safety. I pull the ground as sparks are less likely and you can see I put a copy of Chairman Mao’s Red Book in there to keep the ground from touching the post. The chairman serves the people once again.
On my bike the electronics are under the tank so first read the remove the tank article.
  • Remove the tank.
  • Make a diagram of current wiring. The ground should be easy to spot and mine has two wires to it as it also grounds the diode board.
  • Red is to the diode board. Green is to the stator.
As you can see my regulator is a small black unit nicely mounted with two screws to the frame. On my bike the red and green were indicated by a small tab on each input. You can see the tabs in the picture. Since the diode board is next to my regulator you can also see where it goes to double check. Your bike may have an old style points regulator but the wiring is basically the same.
In order to get clearance I had to mount the new regulator on an angle. Once I had a basic mounting spot I determined how long to cut my wires.
Cut off the regulator connector wires and add your choice of terminals. I wanted to be able to reinstall the stock regulator easily so I used ring terminals. I did not have shrink wrap in green so I used blue for that wire. The other two are soldered and shrink wrapped in the correct color.
Next I mounted the regulator on one screw and Locktited it.
  • Thanks to an old Ikea bracket left over form one of my wife’s projects I made a little “L” bracket to adapt another screw for support on the other side of the regulator. This is so the stock units may easily be returned to service for a road repair. They are small and easy to carry as a spare. I used a bolt with a 10mm head so that only one wrench would be needed to change it. The others use 10 mm nuts.
  • As you can see I cut a wiring connector in half as I only needed three connections. I mounted it to the regulator back with Velcro. If it holds electronics in the Space Shuttle it may work in a Chang.
  • Check all connections and reinstall the tank. Check for gas leaks.
  • Reconnect the battery.

The end result for me was to gain a half volt output. This should not hurt the windings and may make a difference in how long my battery lasts between charges.