Page 5 – 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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Recognition & Safety

Conspicuity …Recognition …Safety ….

This article deals primarily with improving recognition and speed of recognition…hopefully leading to action by drivers of ONCOMING vehicles (whether from your front, rear, or sides), but also covers how YOU see other vehicles.

Many safety agencies …and studies, …have proven that safety is enhanced for motorcyclists having modulated headlights …as the pulsing light attracts attention, particularly important to a motorcyclist, who wants, or should want, an oncoming driver to notice & recognize that a motorcycle is there. This has been shown to reduce left-turn accidents, & in general, reduce most biking accidents.

Studies have also proven that bright clothing and certain colors of helmets help reduce accidents considerably.

State and Federal Governments testing and reports is NOT extensive for motorcycles, nor is private/commercial testing/reports. While many effects do cross-over between carts and trucks and motorcycles, the information is spotty about specifics for motorcyclists. Further, there is a considerable amount of wrong ‘information’ in common use or understanding. Especially notable is the paucity of knowledgeable effects of movement and head positioning of drivers/riders of vehicles on recognition times; although there are other things, including lighting, colors, etc….and these are vast subjects. Many of the technical details are in this article: http://bmwmotorcycletech.info/hdlite.htm
The information in that article is extensive. I HIGHLY suggest you stop here, and read that ENTIRE article, before proceeding!

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Tachometer, Speedometer, and Odometer Calibration

BMW odometers tend to be quite accurate, and all the speedometers EXCEPT the 85 mph ones (which are usually accurate), tend to read high by 6 to 12%. This is ON PURPOSE by BMW. See the article hyperlinked just below, which is more detailed and has the information on why the inaccuracy, and MUCH more.

Recalibrating a speedometer is a touchy job, of messing with such as hairsprings, and is best left to an expert.

Speedometers/odometers have W ratios printed on the face, and they must correspond to the rear drive ratio, see the charts on the author’s website, which is more expanded than on this airheads.org website. The following hyperlink to the author’s website has all the information you would want:

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Speedometer Repair

Thanks to all esp. Paul Glaves, Jeff Saline, and Randy Mallon

After some probing I found the upper RT silver gear that transfers drive from the total mileage to the trip odometer to be loose on the shaft and causing the trip odo to run intermittently. Using minimalist approach and a tooth pick I first carefully dipped the toothpick in alcohol and cleaned the shaft without disassembly. Steady hands and a watchmakers magnifying loupe helped. When that dried I put a drop of liquid crazy glue an a piece of plastic and using a toothpick I dipped it in glue and than transferred small amount to the shaft above the gear keeping it upright so capillary action will draw it downwards. I am now considering a good spot to drill a 1/4 inch hole and put a Gortex patch over it to try to get rid of fogging.

Jeff Saline cautions: One thing I don’t remembering anyone commenting on is allowing super glue the opportunity to out gas outside of the instrument housing. I haven’t ruined a lens yet but understand that if you use super glue and immediately reassemble the instrument housing the super glue will out gas and fog the instrument housing lens(es). I was repairing a high beam indicator blue lens the other day and have had the instrument out gassing for 6 days now. I recall hearing 24 hours is enough time

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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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Headlight Switches & Headlight Relays

This article was originally written (and since then, expanded/edited numerous times) because someone asked about the left-hand switch of BMW Airhead motorcycles if using higher powered headlight bulbs. He did not understand why the existing stock headlight relay would not automatically eliminate wear on the switchgear. The simplified reason is that the stock headlight relay does not do what many think it does, at least on most, especially later, Airhead models. Variances of his question have come up many times, often on the Airheads LIST, but also on various other forums, and even for other BMW models.

It is important to know that the main purpose of the stock headlight relay FROM 1978 is to turn off the headlight, leaving the dash lights and rear running lamp on, during the time the starter motor is cranking the engine. The relay turns off the headlight during cranking, and that’s all.The stock headlight relay from 1978 also does not do theswitching between high & low beams. NOTE that the high beam flasher (‘passing lamp’) function remains, due to a green wire from the ignition switch, as a separate circuit. The headlight relay may or may not turn off the headlight, during engine cranking, depending on year, model, & country shipped-to. On some Airheads, the high beam flasher button (‘passing lamp’ function) MAY be available with the ignition off. It is a matter of where the green-colored wire goes to. It is easy to move a green wire at the ignition switch, and thereby have the ignition be ON, but the headlight OFF, in the PARK function, but there is more to this, and this is not the point of this article.

Using additional relays to control higher-powered headlamps (stock is 55/60 watt) is a must; although some have gotten away with not doing so for some time. Note that the left bars switch assembly is fairly expensive. It is not designed to handle high-powered headlamps, and it would have been, …perhaps, …better if a relay had been used by BMW to handle all the current flow to the low and high beams. This is not difficult to accomplish, and such as the Eastern Beaver kit does it. With that kit installed (or, your own two relays), the bars light switch(s) would only pass current to the extra relay’s COILS. This means that using accessory relays will reduce wear on the left switchgear even with the stock headlight; and usually will increase light output slightly due to a more direct current path from the battery to the relay. This increases the headlight voltage to closer to battery voltage….another way of saying this is that a more direct power path reduces wire and some switching losses.

Sources for appropriate relays are any auto-parts store. However, www.EasternBeaver.com sells complete plug and play kits for your motorcycle, and they may even still have a version with a modulator if you wanted that.

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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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Rekeying a Seatlock

Recently I had occasion to replace the seatlock in my R100, which was old, and rotated in its housing, making it hard to actually lock the seat. I checked in with my local dealer, and they said I could get a generic lock, with a matching key, for $23, or I could get a matched lock (set up to work with my existing key) for $50 and 3 months wait.

I decided I’d rather spend $23 and practice my locksmithing skills. This is an article describing how to do the same thing, while hopefully avoiding a few of
the mistakes I made in the process.

Take a look at this page in general (lock picking) and particularly page 5 from that series for some good visualizations of how a pin-and-tumbler lock works. This is the type of lock used in the seat of the R100 (and probably many other similar vintage Airheads).

Overview

This procedure is broken down into 4 basic parts: getting the lock out of the bike, getting the pins out of the old lock, putting them in the new lock, and putting the lock back in the bike. While the specifics of installation, removal and pin-access may not apply to other locks on the bike (or in general), the rekeying steps can easily be applied to other locks.

Without any instruction, it took me about 30 minutes to do the actual rekeying, having spent 15 minutes beforehand, removing the lock. Reinstalling the lock took about 10 minutes, but would have taken less if I’d kept the seat on (I wanted to take pictures). I think it’d take most people 30-45 minutes to do the whole thing if you read through and understand these instructions.

The Procedure

I’ll describe this in a step-by-step method, referring to pictures as appropriate. Click on pictures to enlarge them. Comments about what I did are in italics.

Step One: Remove the lock from the bike

The seat latch mechanism is attached to the bike by
way of two long screws that thread into the same plate that holds the side handle and the latch button. The heads aim back towards the tire/center of the bike. It’s easiest to take off these screws with a very short #2 phillips head screwdriver, but a longer one will do. Just unscrew them, and the latch box and cover will come off in your hand.

The lock is secured to the bike with a metal ring, that’s then attached to the body lock with a single screw. The screw is a #1 Phillips screw, and is best taken out
with a fairly short screwdriver again. Once the ring is removed, the lock body should fall out pretty easily. I accidentally messed up the small screw on my lock by using too large a screwdriver. It eventually came out, but was pretty well unusable.

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New Keys for Your /5

I recently finished going through the process of reviving a 1973 R75/5. One of the challenges I faced was that of missing keys. Sure, the ignition nail key was there, but the keys for the seat lock and the steering head lock were missing. I needed to remove the lock for the fork in order to complete frame painting, and really wanted matching keys for both the seat and fork locks if at all possible. This precluded me from simply drilling it out. I was pretty sure that the locks were original to the frame, and that the keys should be the same for each.

So, here is what worked for me…

First, go to your local dealer and buy a few correct key blanks.
Remove the seat lock mechanism, and detach the lock housing. Don’t lose the small screw that holds the lock to the striker mechanism.
Take the blanks to a competent locksmith and ask them if they can make an impression cut key. Keep looking for someone who will give it a try. Now, just so you know, I was advised that they might damage the lock mechanism while making a key in this manner. If they (or you) are uncomfortable making an impression-cut key, the lock may be disassembled and the tumblers opened up for their key making efforts, but it is critical that they get the pins back together in the same order to have the fork lock work with this key.
OK, we’ll assume that you have a key that works with the seat lock cylinder. You will try it in the fork lock and, surprise, it won’t work!! Here’s what to do:
Look at the key that you have. You should see four valleys in the key blank, which were cut by the locksmith. You will also notice that they are evenly spaced along the key, and also that there is room on the end closest to the handle of the key for another cut to be made. Starting at the end of the key furthest from the handle, we’ll refer to these as cuts #1, #2, #3 and #4. The trick is that the seat lock uses four tumblers, and the fork lock uses five. You will need to cut the last one, #5, yourself.

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Bike Storage Preparation

It’s that time of year again, so I thought I would post the storage procedures that are contained in the 1978 BMW Owner’s Manual for those of you that don’t have access to such. The following is a reproduction of the storage procedures specified by BMW on page 35 of the 1978 BMW Owner’s Manual:

If you intend to lay up your motorcycle during the cold season of the year or for a long period, the following precautions will help to guard against corrosion and superficial damage:
Drain the oil when the engine is warmed up, clean the oil mesh strainer and oil sump.
Add corrosion inhibiting oil up to the lower mark on dipstick (app. 1 Liter = 1.05 US quarts). Run the engine for about 1 minute off-load. Remove the oil filter and close the empty filter chamber. When storing for more than 6 months, drain oil from gear-box, swing arm and final drive and add corrosion inhibiting oil. Contents: gearbox 0.4 liter (0.4 US quart), swing arm 0.05 liter (0.05 US quart). Place the machine on its center stand, engage 2nd gear and turn the engine at a fast idle for a few seconds.

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