So here is a little write up for replacing the handle bar controls on a 1987 BMW K100,
I initially removed the handlebars because the K100 was originally an LT model with very high rise bars and I wanted something sleeker. 7/8 bars were the most easily accessible but that would mean replacing the throttle tube, clutch and break levers and the buttons and controls on the bars. Secondly I did not like the big box of buttons on the stock controls. Finally I wanted to move the turn indicator switch to a toggle switch on the left hand, rather than one on each side with the turn off on the right.
Originally, I had planned on using some Chinese controls that I have used on some other cafι racer projects I have built, but the left control also has a cable that the choke works off of and none of the aftermarket controls had a lever to engage the choke. So I just began looking for left hand handlebar controls on eBay. Nothing after-market filled the bill of a high/low beam headlight switch, toggle switch for left and right turn signals, horn and a built in lever for the choke. I came across a used 2002 Kawasaki ZZR 1200 left hand control that has a choke lever built in, the high/low beam switch and the turn signal toggle switch. The same seller had a 2010 ZX10 right side control with kill and starter switch, so I combined shipping and ordered them both. They matched up well, were smaller than the stock ones, and look in great shape .(If you are wanting to do a similar switch I dont have the original Kawasaki Part #s but a simple OEM part search at a place like Bike Bandit will get you the information. Or look on eBay like me. I got the units for each under $15)
The Left controls (From the ZZR1200) were a little challenging to figure out until i figured out that the turn signal and the horn button shared a ground on the stock switch. Plus I had to bring the wire for the right side turn signal over from the right side stock controls and ground the signal stop switch on the right as well. The nice thing about buying two bikes to make one complete running bike is that you have spare parts, so I was willing to basically cut the wires, open up the stock controls and take it apart to see what wire connected to what switch along with my Hayes repair manual wire diagram. If I screwed it up too bad I could always grab the switches from the donor bike and put everything back by reconnecting the wires.
So here is the way I wired up the turn signal toggle, High/Low beam toggle and horn button on left hand control.
Turn switch toggle & Horn:
From ZZR control --------------- to ---------------Stock K100 wire harness
1. Orange + Blk/Grey (from Horn button).... Brown
2. Blk/Yellow
..
. Brown/Yellow
3. Green
Blue/Red
4. Grey
.
.
. Blue/Yellow (from the turn signal
button on right control)
Hi/Low Beam switch:
From ZZR control --------------- to ---------------Stock K100 wire harness
1. Red/Yellow
. Yellow
2. Blue/Yellow
Yellow/White
3. Red
White
Unused Blue/Green - Extra wire for parking light.
Here is how I wired the kill switch and starter button on the right side control. (The ZX10 control has an extra switch that is unused at this point so there will be two extra wires that are not connected when you are done. Also when I wired the ZX10 control up and turned the kill switch to run the break light turns on. I am still tracking that issue down. If I can not figure out the cause I will just runt the break light switch as a separate system from the rest of the wiring harness and snip the original break light wire. At this point I still have the original brake lever connected so it may be an issue with the stock brake switch and not my wiring of controls but we will see once its all buttoned up.)
ZX10 Control ---------------------- To ------------------ Stock BMW K100 Wire harness
1. From 1 side of Ignition button Blk/Red
Blk/Yellow
2. From 1 side of Ignition button Blk/Red
Blk/Green
3. From Kill Switch , Yellow/Red
. Green
4. From Kill Switch, Red
. Green/Yellow
5. Brown to Ground (-)
6. Brown White to Ground (-)