R100GS Euro Headlight Switch Upgrade

Is it just me, or is there something un-American about not being able to turn off the headlight on your motorcycle? Especially on a dual-sport bike that spends a significant amount of time donking along at low speeds off road where the factory alternator can’t keep pace with ignition system and headlight drain. Ironically, there is a solution to this problem in the form of a factory BMW part used on bikes destined for delivery every place but America.

As shown in the photo at left, the BMW part number is 61 31 2 305 232, and the cost is somewhere around $75. That’s a ridiculous price for such a simple device, but when you compare the cost to that charged for an equivalent K-bike switch it’s a screamin’ bargain. Your friendly dealer may have to scratch around a bit in the European versions of his parts catalog to locate it, but larger dealerships should be familiar with where to look as it’s a fairly popular upgrade. Even better, it’s also one of the easiest to install, so let’s get started.

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Broken front & rear brake light switches

This article is not concerned with the hydraulic pressure activated brake switches. Those switches, originally 34-31-1-233-959, were replaced with 61-31-1-244-334. You can probably substitute the switch used on old VW Beetles. Napa carries that switch as number SL143. There are other such switches: 3 terminal version is NAPA SL159, VW 113945515G; 2 terminal version is NAPA SL147, VW 0344004003.

This article IS concerned with the mechanically activated brake switches.   All R series bikes FROM 1985 model year through 1988, & SOME 1989 Airheads were affected. ALL models of Airheads for those years!

BMW Service Information Bulletins were issued regarding the front & rear brake light switches, brake lever, etc. The bulletins applied to both Classic K bikes & to Airheads, but not exactly the same way. There were bulletins issued in 1987, updated in 1988 & a formal recall in 1989. Later bulletins were longer, with more details.

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Headlamp Cutout Switch

This is simple and self-evident to most anybody with a soldering iron but here we go….

First a primer on headlamps. Rated at 55 watts, an H4 lowbeam headlamp consumes around 55 watts, I guess, which is something like 4-5 amps. With a 240 watt alternator and with barely any charge below 2500 rpm, goofing around in the city, prior to cranking on a cold morning, or when your electric system is failing, it would be good to be able to switch off the lamp. Moreover, the parking lamp is on all the time and can make-do for a substantial part of the safety and regulatory issues, especially in the daytime. Finally, if you need some lamp action, you can always flick on the highbeam the two habitual ways which are unaffected by this mod.

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