Page 14 – Airheads Beemer Club

Buying or Selling a Motorcycle

This is not an article on pre-purchase-inspecting a BMW air-cooled twin motorcycle (aka Airhead, manufactured 1970 to 1995). Nor does this article contain information about how to prepare the motorcycle for sale. This is an article for a seller and purchaser about safety in negotiations and making a deal, test rides, handling a title, etc. The author’s website contains well over 100 articles on maintenance, but I do not necessarily expect you to read them prior to, for example, purchasing a motorcycle. If you are new to BMW Airhead motorcycles, I suggest you post an inquiry to the free Airheads LIST, for comments on things you should know about Airheads, and if you have a specific model (and perhaps year), or specific questions, that LIST is THE place for inquiries. Different years and models have specific things to know and be aware of. You may join the LIST here: http://lists.micapeak.com/mailman/listinfo/airheads

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CAN-BUS and OBDII. What are they? CAUTIONS on using de-sulfating battery chargers? What’s the future?

Can-bus is being discussed here primarily to give you some knowledge about it, even though it is not used on Airheads.

Can-Bus is the same as CANBUSS, CAN-BUSS, Canbus, CanBus). OBD means On Board Diagnostics. OBDII or OBD2 is the second version, in very common use now. Can-Bus MAY be associated with OBD in a vehicle, and it may not be.

Can-Bus is a method, hardware & software; to enable communications between ‘electrical & electronics things’ on your vehicle; these ‘things’ can also be mechanical, with electrical sensors. Can-Bus stands for Controller Area Network, & the ‘Bus’ part is explained later herein.

As you will see in the section on the future, it can do a lot more than just in-vehicle communications between ‘things’. While Can-Bus will be mostly discussed here, as it is installed by BMW in your bike (was not in Airheads), etc., the information may be similar for any system such as all the varieties of OBDII….all modern cars have such a system; & a diagnostic plug to access it. Can-Bus systems have the ability to transmit information between components at high speed, & to actually make changes in the operation of items. OBD can do some of that, but most think OBD is just diagnostic, retaining information in memory, until downloaded for diagnostic work, or such work can include erasing memory, modifying how systems work, etc. But, that is not really true ….it can be a serious part of actually operating the vehicle systems.

Installing an accessory electrical outlet; also, Hella-DIN adaptors with USB output

Recommendations forDIN adaptors to USB connectors; also wired versions:

It is not easy to find these; especially for good reliable ones with plugs that do not release from vibration, etc….and at a reasonable price. I tested the following products for temperature, output, regulation, ETC. Price is reasonable. These connect to your motorcycles electrical system, either to the battery, or to the system after the ignition switch, or simply plug into an existing DIN jack (or, one you add) on your motorcycle. These adaptors I recommend are NOT cheap cigarette lighter socket plugs but quality Hella-DIN types, that grip well into your socket. All have 5 volt USB type outputs. Single and dual versions, either with 2.1 or 3.3 ampere ratings for output.

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Airhead Lift

For a number of routine and repeated maintenance jobs, you need to raise the bike. Here is a classic cheap Airhead approach to getting the bike high enough into the air to easily remove a rear tire, work on forks, etc. and to do it alone.

Basically, we are going to put some blocks under each foot of the centerstand, tilting side to side to get the blocks underneath. But centerstands and bike geometries vary some and so you might wish to experiment a bit before rushing ahead to cut all the lift-blocks.

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.

Ampmeters versus Voltmeters

I see little reason in having having an ammeter permanently installed on any BMW motorcycle, unless you have special circumstances. I foresee several drawbacks, not the least of which is a potential fire hazard, which includes burning up your bike’s wiring; besides the usual situation of LESS reliability with many modifications; especially with added electrical items. I will lay out the benefits, and the problems, for both ammeters and voltmeters. The GEN lamp provides quite a bit of information if you interpret it correctly….but it may not be enough FOR YOU.

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.

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.

Centerstand Repairs

Owners of early BMW twins are divided into two sorts; those whose centre stand bolts have failed and those whose bolts are going to fail soon. The root of the problem is that on the pre-square air filter models the stand pivots on bushes retained by a pair of bolts which screw directly into the frame. The continued heaving on and off the stand eventually loosens the bolts and the threads in the frame will start to fret. Retapping the frame to the standard thread (M10x1.25) and replacing the bolts delays the evil day, but when I found a bolt lying under the bike only days after doing this, I knew it was time to look for a better solution.

Wheel Bearings

These procedures may seem complicated at first, but in reality it takes only minutes, once you have done it previously. MUCH of the information will not, perhaps, apply to YOUR motorcycle, but it all does need to be read, and understood.

BMW Airhead motorcycles are relatively tolerant to abuse and poor maintenance. Our human bodies are not tolerant to being dumped on the road at speed from a motorcycle. Of all the items that are safety related, the mechanically most important are the condition of the wheels, tires (tubes if any), brakes, wheel bearings. For non-mechanical, well, of sorts, one could add the importance of the rider’s clothing, and, in particular, the rider’s condition and competence/skill.

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