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Leaky Bing Carburetors

It is very important to turn off the petcock(s) when you park your bike. This is so even if you have a late model Airhead that has the fuel-shutoff solenoid valve located on the inside of the cover over the starter motor (many have been removed, but the same caution applies). It is exceptionally important if you park your bike in a garage where there is a source of gasoline fumes ignition …such as a water heater, ETC. We do NOT need to hear about BOOOOOM! We don’t want fires, either!

Bing carburetors are commonly known to leak in several ways. The most common is fuel dumping on your boot from a grossly overflowing carburetor, typically from a side vent. Sometimes there is just a slow weeping or a slow leak from the very small hole in the bottom of the float bowl.

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Deer Whistles

Hearing Sensitivity in White-tailed Deer

Ken Risenhoover, Jon Hunter, Roy Jacobson, and Glenn Stout

Although white-tailed deer (Odocoileus virginianus) vocalizations have been recorded and described, virtually nothing is known about “audition” or the range of hearing by deer and other ungulates. To address this need, I conducted some controlled experiments in collaboration with Dr. Jon Hunter at the College of Veterinary Medicine at Texas A&M University. Audiograms were determined for 5 bottle-raised adult white-tailed deer (3 males, 2 females). While anesthesticized, deer brainstem evoked potentials were recorded from the frontal sinus, vertex, and dorsal border of the zygomatic arch. 


Stimuli consisted of 45-ms pure-tone pips (2 ms rise and fall time) from a McNaural SM-400 amplifier connected to a Nicolet Biomedical Instruments “Pathfinder II” and were delivered using Amplivox audiocup earphones held against the deers ears. Evoked potentials were recorded at intensity levels of up to 95 dB for frequencies of 0.5, 1, 2, 4, 6, 8, 12 and 16 Khz. Estimates of thresholds of hearing sensitivity for each frequency were based on averages for 1000 recorded responses.

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This article was originally intended to be a series of articles on sidecars and sidecaring.  I decided not to do multiple articles.  I update this article now and then, date of which is at the end area.

When reading this article, you will see that I have included a considerable amount of my own travails in building my first street-going sidecar rig. I was exceptionally anal about building it to be very strong and reliable with very good handling.  YOU can take advantage of all my work, GREATLY simplifying YOUR work, by reading carefully, and referring to the Author’s website articles on sidecaring, which have many photos and technical details & descriptions not in what you are now reading.  You can save a LOT of time and cost.  There are also articles on how to drive a sidecar rig, and many hints and things to know.


In my earliest Airhead days, I wrenched-on & raced sidecars: BMW /2 and some on the /5 bikes. I won’t go much further here into my track or dirt racing (2 and 3 wheels, BMW, Norton, Vincent). For sidecar racing, during and after my initial position as Wrench, I was often the ‘monkey’ on the platform.   Eventually I became the driver. Back then, I NEVER did any sidecar driving on the street. Over the many years since, I became more interested in street type sidecar rigs, but did nothing, besides attending many sidecar rallies; in particular, the one held in Griffith Park, Los Angeles area.  I was always there on 2-wheels….at least until the turn of the century.
In 2000 I drove a few miles in the countryside on Hal Thompson’s factory Ural rig and found it lots of fun, although I felt awkward (my lack of recent experience no doubt), and it felt very tall, no doubt due to the fact that a racing sidecar rig is VERY low to the ground. I began thinking more seriously about building a rig to compliment whatever solo bikes I had.  There were other reasons too… I’d been suffering for years with back deterioration; and thought then, that the handwriting was on the wall for my dirt riding, let alone solo road riding.  I also wanted something ‘different.’ After 850K or so on motorcycles I was occasionally bored. I had some adventure touring in mind and thought that now might well be the time to have a sidecar outfit for myself.  Serious attention to back exercises has since kept the deterioration of my back to a minimum, although still troublesome. I can’t see myself giving up two wheel riding, not hardly, not until maybe in my eighties. But the idea of a sidecar rig WAS…and REMAINED… very appealing.  

In 2001 I built a sidecar rig for the street, an R100RT-Ural rig. It was very stoutly built.   I had it for quite some time. Some years later I purchased a rig and modified it extensively to my particular tasts, and I still have that one, a K1100LT-EML rig, with EZS tug equipment. I used both rigs on the street, occasionally hard-pack dirt roads, and sometimes drove them on ice and snow, and I have put a lot of long distance touring miles on the K bike rig, with my wife sometimes in the chair.  Over the years I have worked on a lot of street-going sidecar rigs that belonged to other folks.  I have seen some good rigs, and some awful rigs.  Sidecars need to be built Hell-For-Stout; and with real thought put into the over-all design.  They also absolutely must be aligned correctly, which is easier said than done.

Sidecar rigs are also known as ‘Outfits,’ ‘Combinations,’ Gespanne, and ‘Hack-Rigs’. The sidecar itself has had many names, including Hack and Chair.  Rigs are a lot of fun, & often attract a lot of attention from folks who would never think nice thoughts about motorcycles and motorcyclists. They can also be a PITA to learn to drive. They do NOT handle like cars, nor trikes, nor motorcycles. They change their handling characteristics in accelerating, and in braking, and handle totally differently on right turns than left turns. They are affected seriously by the changing crown of the road. They are more difficult, in some ways, to ‘drive’ really well, than riding a motorcycle; and can be more physically demanding….or, at least tiring. But, they are a lot of fun!   They are also one of the better answers for those who want to be ‘in the wind’ but have physical limitations.   Sidecars are NOT, however, just for ‘old guys’.  Sidecars allow you to ‘motorcycle’ even in the Winter.  They can carry a LOT, and even a single wheel drive sidecar rig can be usable on ice and snow.

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Hydraulic Jacks

Above are two inexpensive ‘bottle jacks’.  A 12 inch tall ‘square’ is in the center of the photograph, and a 12 inch ruler below to give you an idea of size. These two jacks happen to be the versatile types that have tops that screw-down into the jack pistons and those jack pistons are shown with jack pressure released, that is, down.

Making an anvil if your jack does not have a particularly useful one, as in the photo, can be simply made from a piece of iron pipe, cut with a hacksaw to make a half round length. This can be much nicer than the bent metal type in the right side of the above photo that I made in a couple of minutes.  The hacksaw-cut type is also described in this article. The jack on the left has a top I made from aluminum stock.

Below is a photo of my small scissors jack. It is rated at 2 tons. I find this jack quite useful. I have made a curved cradle for the anvil top of this jack, as shown. As on my other jacks, the curved cradle is rotatable. This jack cost only a few dollars a bit more than the inexpensive bottle jack type I discuss in this article.  Note how small this floor jack is….and it is also not very tall.

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Headlight modulators

Headlight modulators are, or can be controversial, with differing viewpoints & arguments for & against. Some find modulators annoying. I believe that is, perhaps not always, folks seeing OTHER folks’ modulators, not their own. Some are concerned about oncoming drivers fixating on one’s modulating headlight & aiming for them, this seems to come from the idea that a motorcyclist tends to ride to wherever they fixate on. Studies have shown that adding lights at the rear (& in some instances the sides) of motorcycles makes them more visible and recognized earlier. For the rear, the lights should be red & as differentiated as possible between Run & Brake. Bright clothing, greenish-yellowish helmets, etc. …all have been shown to reduce accidents. I see no one arguing about ‘fixating’ on THEM.

Whether or not to install a headlight modulator on YOUR bike, is a personal choice; the USA government has not made them mandatory. My comments in this article apply to the USA, as headlight modulators may not be legal in some other Countries.

There ARE reasons that motorcycles are specified, since 1978 in California, & specified in many other States, to automatically, upon ignition turn-on, to power headlights ON, without having to manually turn the headlight(s) on. State law & Federal law are not necessarily the same thing, but, typically, Federal law supersedes. In this instance, always on headlights after a certain year model does apply. There is also an argument about certain cars, such as late models, having constant-on headlights …the argument usually is negative, as motorcyclists want only themselves to have such lights, to differentiate between them and cars. That’s a decent argument, but tends to favor modulators in use during the daytime.

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Adding Running Lamp To Turn Signals

This article deals specifically with converting the two Airhead rear turn signals into running lamps, while retaining the original turn signal function. Considerable information is applicable to a FRONT turn signal lamps conversion, if desired.

This article does not deal directly with conversions to the Classic K-bikes, such as the K1, K75, K100, K1100. MUCH of what is in this article on the physical modifications ARE applicable to K bikes, Oilheads, ETC. The K-bikes have a bulb-monitoring relay; which complicates matters, & information on modifying them is in item #2 in

Adding running lamp functions to the rear (and/or front) MAY add to safety. You get more lights, & you have two lights that are illuminated in case your one rear stock running lamp burns out; many bikes have only ONE rear running light & if it fails you might be INVISIBLE to cars coming up towards your rear; which is one of the arguments FOR this conversion. My primary argument against this conversion is that the turn function is, or can be, less noticeable to car drivers ….due to the running lamp function in the same lamp, same housing (could be separate lamps on fronts, some bikes). You must decide for yourself. Proper installation with proper color of lens & proper lamp bulb may negate such arguments.

The conversion may not be legal in some States,  ….if the lens is not re-colored to be RED (or the lamp colored red). Careful selection of bulb & possibly inclusion of reflective aluminum foil may improve brightness.

There are potential problems if not done well, the turn signals might then not be as distinctly different from the running lamp function. Properly done they certainly CAN be very distinctly different. Several ways to go about it, including a small unpainted or no red insert area, in the middle of the lens, or, a band across the center. One can find red bulbs plus use aluminum foil as a reflector, if desirable. The reflectors & lenses of the stock bike are OPTIMIZED for incandescent lamps, NOT LED types. I do NOT recommend LED lamps (of any type I have so far seen) for purposes of this article although wide angle LED lamp structures may now be available. RED LENSES have been available at times, almost a perfect direct replacement for your amber ones; you need only to provide a rubber gasket (easy and only if you wish to), and in a few instances about a minute of filing, depending on if plastic or metal case. The ones I have seen have an even better than stock amber lens light diffusion/reflection in the lens. Check such as Ebay. The ones I saw have number K22750 and K32724 on the plastic cover & were made by CoolBeam MTP; they are marked as SAE & DOT approved. These are hard to find in the USA. I have a set on my bike. If you find a source, PLEASE let me know so I can publish it here.

The conversions in this article are for incandescent lamps. You are free to experiment with plug-in LED lamps, but I have not done much experimentation so far.

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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:
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 website.   The following hyperlink to the author’s website has all the information you would want:

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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, 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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