wiring – Airheads Beemer Club

Accessing the Headlight Bucket

The fairing-equipped Airheads began with the 1977 R100RS. The headlight bucket is basically the same as in the unfaired models (except for later models not having fuses, etc., in the bucket). The bucket is not part of the fairing. On the RS and RT the bucket is located behind the front-most protective glass that is part of a ‘tunnel’ assembly with a large protective rubber molding with an outer glass, etc., whose design is such that it offers a relatively smooth front surface to oncoming wind, etc. The expensive outer glass has some orange lines on it. There is no purpose to those lines (stories abound, all wrong) except to draw the eye away from the quite large front glass. While the orange lines were purposely installed for that stylish effect, the headlight/bucket was quite far inwards from the front of the fairing, and thus the outer fairing tunnel glass needed to be of substantial size to prevent narrowing of the headlight beam. There is no aiming or other purpose to the orange lines.

Don’t do any disassembly of the fairing beyond what is noted below, unless you have a good reason to do so!

1. Fold back, barely (just a small amount), one corner at a time, each corner of the rubberized material surrounding the $$$ glass in the fairing. That will just barely expose a phillips screw at each corner.

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Wiring Color Codes

This covers most of the basic wire colors used on Airheads. As the electronics got more complex, more combinations came into play so it’s possible a few of the more obscure ones may see other uses. Always double check factory wiring diagrams, and yes, even they can have a mistake or two. PowerBoxer.de has a copy of the Haynes ones. And here’s a link for more about Airhead relays and terminal designations.

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Basic Electricity 101+

The below article was written to furnish THREE types of information:

(1) CONSIDERABLE amount of BASIC & SLIGHTLY ADVANCED INFORMATION on electricity & Airhead problems. The approach used here is probably different than in most manuals & troubleshooting guides. Although some hints are given in this article on some common faults, this article should be used in conjunction with my other articles, particularly: http://bmwmotorcycletech.info/electricalhints.htm

(2) Common problem areas, explanations of some of the circuitry. A discussion of such as batteries; starter motors, voltage regulators, etc. Other articles will get far deeper into these things.

(3) An addendum that may discuss particular points that has come up, or some topic of interest. Some is at the very end of this article.

Available to you are certain helpful booklets from such as Motorrad Elektrik, Chitech, Haynes and/or Clymers manuals (and, perhaps, a schematic in the rear of your owners booklet or on the Snowbum website). In my opinion the Chitech electrics manual and the owners book or factory schematic, or schematics on the Snowbum website (and some elsewhere’s, and I have links to these on the Snowbum website), are THE BEST sources for electrical information for the Airheads.

I recommend you at least purchase at the Chitech Electrics Manual. The Chitech (Chicago Region BMW Owners Assoc.) BMW Electric School Manual is THE BEST manual for BMW electrics, from basics to full-blown technical details, components, diagrams, etc., & includes the singles & all Airheads; even some on the /2 era. It is VERY complete. Only a few errors, for which i wrote an article/Critique: http://bmwmotorcycletech.info/chitechelmnl.htm

See http://bmwmotorcycletech.info/url.htm for more information on Chitech, and how to order their publication. Some of the total-bike schematics are not reproduced well, that is the only substantial problem with that manual. Get the manual anyway.

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Electrical Wire Upgrade

To help the voltage regulator and the entire charging system, an easy and inexpensive upgrade is to replace old, small, worn and sometimes corroded stock BMW wires with a set of upgraded heavier wires you make yourself. Here’s how:

The Best Wire to Use

For the best wire, go to a marine supply store and look at their selection of bulk wire. They will have wire as thin as 22 gage and as thick as 6 gage, with costs ranging from $.11 to $.49 per foot. The marine wire is rated for 600 volts, is oil-water-gasoline resistant, and is made with very fine multiple strand wire. The finer the wire used in the multi-strand wire, the more flexible the wire will be to handle and install, which is important when working within the tight confines of a motorcycle.

If you can’t find a marine supply store, auto parts and hardware stores also carry quality multi-strand wire at reasonable prices. I have used this material in the past and it works well but is not as flexible as the marine grade wire.

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