I was fortunate enough to be able to spend some time in the GMR vendor area and observe Sanjoh install one of these LED headlights in his newly acquired R100GS. I took a few pictures of the install process; then purchased a couple of these bulbs for my airheads. 20 Watt draw vs 55 Watts.
Below is the airhead GS with the stock H4 installed. First, lower the handlebars to make some room to work. Shown is the back of the stock H4 bulb installed, but the end plug has been removed. The rubber cap is still attached - this rubber cap will require a minor modification.
The rubber cap has been removed and the back of the stock bulb is shown. Also shown is the wire clip that must be gently spread apart to allow the stock bulb to be removed. (This works much better is there is a bit of room - did I mention that it really helps to loosen the clamping bolts and rotate the handle bar back a bit?)
As shown in Sanjoh's earlier pictures, the new LED H4 bulb has a sub-socket that is secured with a bayonet-type locking mechanism to the bulb. The sub-socket should be removed from the LED bulb and installed where the old bulb was located. Then replace the wire spring clips to hold this sub-socket in place.
The rubber cap needs a minor modification. That modification is to cut a hole in the center where the old plug was connected to the socket. If you want to have an extra, unmodified rubber cap, for the GS it is part number 63 12 1 459 377 and cost about $14. Shown is the rubber cap re-installed over the sub-socket that is clipped in place. (Yes, this hole was cut a bit too large, but this was the first installation of one of these bulbs).
Below is the LED bulb with the sub-socket removed. The bayonette-type of connection for the bulb the the sub-socket is shown. That is, the bulb is inserted and given about a 1/8 clock-wise turn.
Here are the hands of Sanjoh installing the LED bulb. This was actually an early test at the install. Did I mention that it really helps to have some room (rotating the handlebars back a bit is the key).
Shown below is the newly installed LED bulb in the R100GS. There is a pigtail (about 6 inches long) that is connected to the plug.
Here is the GS with the stock light on - can hardly tell that it is on - hence Sanjoh's motivation to get the new LED bulb installed - GMR GS ride coming up!
While not as an impressive a demonstration as the underwater pix for the aux LED lights (in the other thread), here is the illumination with the new LED bulbs. This is quite a big difference from the earlier photo.