CJ750 toolbox
CJ750 Ignition Switch by John Nash
It would appear that the Chang ignition switch, as fitted to the 12V bikes, isn't too good a quality. The fact that they are only 60p each should be a clue. When mine stopped operating my lights, I had the option of buying more of the same from China, or to look about for something that would be a little more rugged.
The switch on our (later) Royal Enfield has run for a fair while, would fit into the CJ750 headlamp shell and is dead cheap. Mine was 6 and branded MINDA (the Indian company that makes all the Enfield switch gear,  ammeters, etc.)

Make sure you obtain the Enfield switch that has multiple "poles" and is three position (turns clockwise, anti-clockwise, the key only being removable in the off or middle position). The terminals themselves are screwed and will only accept small ring connectors, so you will have to take off the spade connectors and solder small rings.

Mine didn't iterfere with the plastic "generator light" as I'd changed those (see below).

The Minda switch fastens the same as the original (with a 24mm nut) and fits under the cover and looks pretty much identical when in the headlamp shell.

The headlamp for Changs works the same as those for Urals; interference fitting at the top (usually a raised edge or sometimes a small lug) and single screw at the bottom of the headlamp shell. When replacing, locate the top over its edge first and then push closed at the bottom, before screwing home. The ignition switch removes easily by undoing the nut on top and easing it out from inside the headlamp shell.

My Chinese ignition switch has only three wires:

1. One (is red) and the input live (check it with your circuit tester).

2. One is an output and is live in BOTH the anti-clockwise and clockwise key positions. This goes to the top brass "live strips" and is the "ignition" live.

3. One is an output and is live only in the anti-clockwise position. This goes to the bottom brass "live strips" and is the "lighting live"

My Chang has the atypical two brass "live strips" in the headlamp shell, the top one runs the ignition components etc, the bottom one runs the lights. Things are not as simple though as the bottom brass "live strip" feeds the rear light and internal headlamp bulb directly and then the lighting handlebar switch.

I am always worried about switching the full current through the switch, as opposed to using relays, but it seems to work on my early Urals okay. If I was that concerned then I'd fit more than the standard single fuse...

You can test the Enfield switch by placing a battery live to one terminal and then turning the key clockwise and anti-clockwise and using a tester to see which other terminals become live. Using this method, I determined that terminals 2, 4 and 6 (they are all numbered) were the ones I needed:
1. Terminal 2 - input live.

2. Terminal 4 - output to top brass "live strip" for ignition (this terminal is live in both clockwise and anticlockwise key positions).

3. Terminal 6 - output to bottom brass "live strip" for lights (only live in anti-clockwise position).

One connected, tighten up and check everything and go in for a cup of tea!

           
CJ750 Charging and speedometer bulbs
The later Changs, while having the earlier style warning light glass in the headlamp, have a less than ideal internal bulb layout as the bulb that lights the speedometer is set quite a ways into the shell and also lights up the generator glass at night (really annoying). The generator bulb is also set back and can be hard to see during the day. The solution was to fit sealed warning light units into both holes AND also to leave the bulb that lit the speedometer in place.

I obtained two "large warning lights" from Vehicle Wiring Products. One red and one blue. I needed to knock out the old glass in the headlamps and widen the holes slightly to the 17mm hole required.

The red light was fitted where the generator bulb was (remove the white plastic stuff that holds the old bulb). Two new wires need to be made up to connect, so just make sure you remember where the old ones connected when you put in the new ones.

The blue light was fitted on the other side and I made this into my "high beam" warning light. You could fit an orange one and make it an indicator warning light if you wanted. (I have a flasher relay with buzzer for my indicators). For my high beam warning, I simply soldered one wire to the wire that runs to the headlamp bulb and one went to earth.

The result is less "classic" externally. but certainly alot more useful.