Late last year while driving home at night I passed a Harley going the other way that had yellow marker lights on either side of the headlight. This looked real good, and I thought this would be easy to set-up on the old RT.

There is a web site (http://www.epmperf.com/) that advertises Run-N-Light kits for the K100 for about $35, but the web page wasn't working properly when I tried it last.

So, being an electrician in my former career I figured I could do it on my own (for about $40).  :|

The 1157 bulb has been around for some time now. Not sure if it has a small transistor or diode inside, but the parking light element completely cuts-out while the blinker is flashing. 

The first step is to obtain a pair of duo-element fixtures designed for the 1157 bulb. Easier said than done as SAE size is all that's available around  here. The faring cut-outs are metric, but the fit was close enough. A strip of duct tape to the back of the fixture elimanates any minor rattles.

INSTALLATION: Figure 1:  (left) The wiring is fairly simple; OEM ground wire goes to the fuxture base (a, b) and OEM blinker wire to the fixture. Both wires on the fixture are black, so it's possible to connect to the wrong one (we'll work that out in testing).

(right) Next step is to make-up a short "Y" bundle (d) that connects to the hot parking lamp connector. The other ends of the Y connect to the remaining black wire on the duo-element fixture, and here I've used quick-release bullet connectors. Note the original wiring remains unmodified, so this entire process is easily reverseable should the follow-on owner (FOO) desire it.

TESTING: First turn the ignition switch to PARK. The new marker lights should come on with the tail lamp. Now switch the ignition to ON and see that the marker lights come on with the headlamp. Now with the ignition still on, push the left turn signal, and then the right, to see that the blinker lights come on. If this doesn't happen, then the wires in the fixture are backwards. Turn the ignition switch to OFF.

To reverse the fixture wiring, first remove the light bulb. Then, gently push the contacts up through the fixture base, swivel them 180 degrees, and re-seat them. Put the bulb back in and test again.

In case you've wondering what happens to the original parking lamp . . . I became concerned by the smallish wire gage used by BMW since this mod essentially doubled the number of bulbs on the circuit. To put the parking lamp back in would triple the number of bulbs, and that seemed a bit risky.
 
Another alternative would be to  put some low current LED's in place of the parking lamp. Again, that would require additional modding and I wanted a simple solution that the FOO could easily un-do. So, LED's were not an option.

The original parking light fixture, with original bulb, went back into the parking light to act as a vapor block.

Now, what to do with a non-functional parking light? An idea came from the recent 2014 picture contest where an owner of a white RS blacked-out portions of the lenz to make it look a bit different (at least when parked). So, I began photoshopping pictures of my RT to see what various headlight treatments might look like. Tried pearl, mirrored, and black, but none looked any good. Then tried faring color (baja red), and that looked pretty decent. The headlight itself appeared some 20% smaller, a little less the "big 80s" look, while the  parking lamp portion simply faded into the background of the faring.

Figure 2 (left) With a can of matching paint made up by the local auto parts store (NAPA), applied about four (4) coats topped off by two (2) coats of clear.

(right) Had to keep it under a heat lamp for a couple days, but came out looking pretty good.

Figure 3: Still a lot of snow on the ground here, so can't get a good outside picture. But, here you can see what it looks like head-on. To the uninitiated it seems nothing more than a seamless piece of molding to hold the lens in place. It's a completely different look for the old RT, and again, if the FOO doesn't like it he can simply razor blade the paint off.

You can still buy them from the company that makes them for $29.95. http://www.run-n-lites.com/pricelist.asp

Or asked me because I have used ones available.

Not sure if it's an issue with the front RT/LT lens but on a few bikes I've parted with rear ones, over time the heat generated by the low filament always being on will eventually warp the turn signal lens.

looks good aj