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:

You must be a member to view complete articles on this website. If you are already a member, you can log in here. If you aren’t a member yet, you can purchase a membership here.

Continue readingMore Tag

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

You must be a member to view complete articles on this website. If you are already a member, you can log in here. If you aren’t a member yet, you can purchase a membership here.

Continue readingMore Tag

12 Volt Clock Light

Ever tried to see what time it is while you’re moving down the road after dark? No, I’m not talking about taking a peek at your Timex, but at your ‘bar mounted time piece, whether it be a bicycle computer or one of the purpose built jobbies that BMW used to make for the airhead GS. If you did, chances are all you saw was a black blob instead of illuminated numerals. Or, if you’re savvy to the little LED jobbie that Sigma makes for their bicycle computers, you fumbled around in the dark looking for the tiny button, hoping you could find it with your gloved hand. That was my situation after I stumbled across the little gem in Aerostich’s catalog, but I wasn’t willing to put up with the switch and battery replacement routine that went along with it. I know just enough about electronics to be dangerous, which was just enough to rig up a 12 volt LED and wire it into the bike’s harness. All that was needed was the LED and a resistor wired in series with it to limit the current through the LED.

You must be a member to view complete articles on this website. If you are already a member, you can log in here. If you aren’t a member yet, you can purchase a membership here.

Continue readingMore Tag

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.

You must be a member to view complete articles on this website. If you are already a member, you can log in here. If you aren’t a member yet, you can purchase a membership here.

Continue readingMore Tag

Panasonic Battery Upgrade

Maybe I worry too much, but I always imagine the worst when the GS tips over onto a cylinder head and the electrolyte in the battery starts sloshing around. The vent tube is routed low enough so that any acid that does manage to escape should make it to the ground without splashing on anything metal, but there’s always the chance that won’t go according to plan. And regular maintenance of the electrolyte level is also necessary to keep the battery in good shape. That’s not a big deal, since removing the battery is pretty easy on the GS. But it’s just one more thing to screw around with, and there are ways of keeping things simple when it comes to batteries. Frankly I was surprised when I checked the log for the R100GS and found that the BMW battery was almost six years old, as it had given no signs of ageing like slow cranking or unexpectedly going flat. But six years is plenty for any battery, and I’d just as soon replace it in the comfort of my own garage than have to bump start the bike somewhere out on the road until I can find something that would fit. I’d had pretty good luck with a Panasonic sealed battery in the K1200RS, and with Digi-Key’s $58 and change price (including shipping), swapping out the wet cell BMW battery for the maintenance free Panasonic was a no brainer. A week after the check went in the mail to Digi-Key, the Panasonic was sitting on the door step.

As shown by the part number on the side of the box, the correct battery for the R100GS is an LC-X1228P, the P referring to the terminal type. We want flat lugs with bolt holes, ideally with positive and negative positioned just like the OEM battery, and that’s what we get with this Panasonic. They call it a VRLA battery, short for valve-regulated lead-acid, and it uses AGM (Absorbed Glass Mat) technology to eliminate the liquid electrolyte. The LC-X1228P is rated at 28 Amp Hours, just like the original. This battery came with a few California specific stickers adhering to the top surface, each of which left a nasty bit of paper and glue behind when I removed them. A little 3M feathering disk adhesive remover took care of the problem, but it also removed some of the printing from the top of the battery and left a hazy surface in place of the shine every where else. Size wise, the Panasonic is about 5/8″ short in the long dimension, and about a half inch taller when measured over the terminals.

You must be a member to view complete articles on this website. If you are already a member, you can log in here. If you aren’t a member yet, you can purchase a membership here.

Continue readingMore Tag

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.

You must be a member to view complete articles on this website. If you are already a member, you can log in here. If you aren’t a member yet, you can purchase a membership here.

Continue readingMore Tag

R100GS 4 Way Flasher Upgrade

Lately it seems I’ve been spending a fair amount of time at the side of the road, either at crash sites or just stopping to look at a map. In these situations visibility is a good thing, and the K bikes I’ve owned all had 4 way flashers as standard equipment. The GS is wired for them, but the bits to make ’em work aren’t always all there. That’s easily remedied with a call to Sam at Re-Psycle BMW Parts, a purveyor of new & used parts located back in my old stomping grounds of Lithopolis, Ohio. Your friendly neighborhood dealer should also be able to get them, but if you’re going to have to wait for him to order them anyway, why pay full boat when you can get ’em used for half the price?

Here’s what you’ll need:

61 31 1 459 224 – 4 Way Flasher Relay, $55.00
61 31 1 244 708 – Hazard Switch, $13.50
61 31 1 244 709 – Symbol, Hazard Switch – Included

Keep in mind that the prices quoted above are for used parts, and might vary depending on the condition of what Sam has on hand and how polite you are when you talk to him. In my experience, Sam’s not real good at answering email, so it’s best to call on the phone. His service is great, though, as I had the parts in hand in less than a week, not bad seeing as I’m now sited in California.

You should also check the part number on the flasher relay that comes on your bike. I understand that the later GSs come with a 4 way capable relay (below, left) already installed, and it should have a number on it that encompasses the last seven digits listed above. The relay on my 1993 (below, right) had the digits 2 306 014, and would not engage the 4 way flasher function. Also note that the 4 way flasher relay is also standard equipment on all K75, K100, and K1100 bikes, and that info might help Sam get you the correct part.

You must be a member to view complete articles on this website. If you are already a member, you can log in here. If you aren’t a member yet, you can purchase a membership here.

Continue readingMore Tag

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.

You must be a member to view complete articles on this website. If you are already a member, you can log in here. If you aren’t a member yet, you can purchase a membership here.

Continue readingMore Tag

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.

You must be a member to view complete articles on this website. If you are already a member, you can log in here. If you aren’t a member yet, you can purchase a membership here.

Continue readingMore Tag

Odyssey Battery Upgrade

It’s a long story, but a while back I ended up with an extra Odyssey PC680 battery, and I thought it would make a nice upgrade for the R100RT. The bike came to me with a Wesco AGM battery of indeterminate age, and it was a monster. It also used the steel hoop type hold down that has a pair of spokes on either side. The Odyssey is much narrower than the Wesco, and the spokes were too long to hold the Odyssey firmly in place.

You must be a member to view complete articles on this website. If you are already a member, you can log in here. If you aren’t a member yet, you can purchase a membership here.

Continue readingMore Tag

Posts navigation

1 2 3 4 5 6 7 16 17 18
Scroll to top