Fixing the clutch switch

Bottom line up front: This fix doesn't work for the 1200/1250LC - the functionality is the same but the microswitches are not only conjoined, but also partially encapsulated in a plastic casing that includes a three pin socket rather than trailing lead.

Nevertheless, I succeeded in effecting a fix, although as I didn't have the opportunity to delve inside the offending microswitch, I don't know its condition and it may well continue its failure mode some time in the future.

The configuration is similar to the 1600 - two stacked switches with the starter safety switch uppermost. The tab of the cruise control switch is depressed in the neutral position and releases when the clutch lever is depressed even slightly, facilitating immediate disengagement of the cruise control before any clutch slippage could possibly occur with the engine still under load. The starter safety switch engages much later, ensuring the clutch is fully released before the starter motor engages.

My starter safety switch was not triggering at all, even with the clutch lever fully depressed. With the micro-switch assembly removed and the switch tab depressed by hand, it would operate correctly. I had the GS911 hooked up so that I could monitor operation via real-time values, 'Clutch switch' being the starter safety and 'Clutch switch 2' being cruise control disengagement microswitch.

The safety switch tab showed signs of wear, so I super-glued a shim plate (cut from a safety razor blade with scissors) on the under side, overlapping a glob of 5 minute epoxy glue on the trailing end to ensure it remained in place should the superglue gave way with use and flexing of the tab. One needs to be accurate in placing the shim as the superglue locks it in place once any pressure is applied. The shim made the switch trigger earlier, but not enough, so I added two more on the upper side, this time without removing the tab from the switch.

I noted in my testing that the switch only triggers some distance past the 'click' so I don't know if this fix will be enduring.

After assembling and testing to confirm satisfactory operation, I removed the switch to place some dry lube on the tabs and lever triggers.

The separate clicks of the microswitches are now clearly audible at the beginning and towards the end of clutch lever travel when pulling the lever in. The starter safety switch now triggers when the lever is about a centimetre from the grip. I'd be interested to know whether this is a typical distance.

The fix I described earlier worked for a while but the switch action became sporadic again so it was time for another hack at it.

I thought I may be able to drill holes into the side of the problematic switch and spray contact cleaner into it to clean and flush out any impurities.

To understand the innards of the switch, I bought a generic one for a couple of dollars at the local electronics shop and lifted its lid to expose the action (not being able to access the inside of the clutch switch).

Marked in red on the first photo are the locations I aimed for on the clutch switch, drilling carefully with minimal pressure so as to not go past the plastic housing and damage inner components. While drilling the top hole, I depressed the switch to attain greater clearance to the spring should the drill go through. The other hole was a bit trickier as my first two attempts struck the inner conductors. Midway between these attempts, I managed to break through the housing sufficiently to provide an entry point for the spray can tube.

The third photo shows the spray jet exiting the top hole, presumably blasting out any impurities that were affecting operation. The spray I used is a contact cleaner/lube which should enhance longevity.

Finally I used some brake cleaner to wipe the surfaces around the holes to remove any lubricant from my contact cleaner/lube spray before covering them lightly with heat gun glue to restore waterproof status..

All is now operating correctly – hopefully it will remain that way indefinitely.

Sorry, I think my post was a little vague. I was referring to the image in the first post of this thread, not the first image from your repair. You can see that the switch is marked with a part number that matches the Farnell catalog. Looking at my clutch lever switch the dimensions seem to line up.

You're obviously correct that the BMW part is more complex than just a couple of off-the-shelf switches, but I feel pretty confident that it is ultimately just a housing for a pair of standard switches, along with terminals and a plug connector. My tentative idea is to create a small housing that holds the switches together and can be screwed into place like the original part. Replicating the plug part of the housing would be difficult, but BMW generally uses Tyco/TE AMP connectors and I think I could make a short harness to a connector that accepts the wiring from the bike side. Mouser, element14, and others sell the plug housings and terminals and I've made some previously for other projects on my BMW cars and F650GS.

All of that said, my switches started working again when I reinstalled them on the bike. I didn't really do anything so I don't consider this "fixed", but it does buy me some time to plan.