I just added a positive battery jumper post to my 1999 R1100S. I wrote up a brief "how to" for the R1100S board, but those of you with pre-2004 GS's or other R bikes might find this useful as I suspect the process is nearly identical on all oilheads. It's an easy mod and looks factory when you're done (see last picture in this post).
The BMW parts you need (at least for the R1100S - other threads have listed parts for the GS - they may be the same) are as follows:
(7) 61137671355 Bracket
(8) 61137671354 Screw
(9) 61137672395 Protective Cap
(10) 07119931050 Washer
I don't recall how much these cost as I got them a while back, maybe $25 or so. Here's what the new parts look like:
Here's the process:
1. IMPORTANT: Disconnect the ground wire on the battery. I know, I know, this probably means removing bodywork to get access to the battery, but this is really not something to fool around with. You're going to be disconnecting a big wire that is ALWAYS hot and unfused, even with the ignition off. (Perhaps do like I did and make this mod when you need to get under the tank for other things.)
2. Remove the allen bolt holding the starter cover on and remove the starter cover. The bolt is a bit hard to fish out - it's at the rearward end of the cover pointing forward. A small allen wrench and little hands work best. After removing the bolt, iIt helps to push the gear shift lever down to fish the cover out.
3. The stater relay is at the top with the starter motor below. The new jumper post is going to attach to the top terminal of the relay which is wired directly to the battery with heavy gauge wiring. Unscrew the hex nut on the top terminal and push wire aside. Again, if you previously disconnected the battery ground, this wire can touch things without consequence, but if you didn't it's "hot" and will spark like crazy if it touches any ground.
There is a small clip that is inside the wire terminal on the top terminal post - you're going to be replacing this clip with the new bracket piece onto which the post will mount. The bracket has a shape that mimics the shape of the clip. (Gotta love German over-engineering.)
4. Put the wire terminal back on the post and tighten down the hex nut. At this point, you've got a nice bracket ready to receive the jumper post through the starter motor cover.
5. All that's left is to drill a hole for the post in the starter motor cover. I measured, crossed my fingers, drilled a small pilot hole, saw how close I was, and then made a minor correction as I enlarged the hole. Or you might put something in the bracket that would mark the back of the cover when you test fit it. If you want to use my measurements, the hole is 12mm in diameter, and the center is 123mm and 26mm from the left/top edges of the cover. A step drill is ideal for drilling a nice hole.
6. Put the starter cover back on, screw the post in the bracket, and put the protective cap over the post. You're done.
A nice upgrade to those of us still soldiering on with our obsolete old bikes (mine's a 1999 with 43K).