What you should know about
used BMW K bikes
First of all: I´m not the one who knows everything about this bike and who has disassembled a couple of them. My only qualifications to write this article are things I´ve learned while looking for a K100 RS, things I´ve read in motorcycle magazines and the fact that I was asked to do so frequently. So, if you´re able to disassemble the K100 in the dark, using a pocket knife only: please be patient or, even better, share your additional hints with me. I would appreciate any tips concerning the K75 and K1100. I have omitted tips regarding test drives because there are various articles out there describing those.
Should I buy a K-Bike at all, or should I look for a different model BMW ?
Well, what do you want your bike to be like ? The K100 is a bike for long distances and, equipped with fairing and hard cases, will make your vacation a pleasure. It´s economical, fast, and comfortable for you and your passenger. It´s not a sports bike although acceleration and top speed are excellent. Suspension and tires don´t meet today´s standard as you may recognize when passing lane markings. On the other hand, the K100 RS is very stable at high speed due to its fairing which causes negative lift. Even if hard bags are mounted the K won´t get unstable.
By the way, I think this should be mentioned, too:
If you don´t meet the “standard” size of a bike rider, you should look for a “K” series bike all the more! Apart from the standard seat, there are a comfort, super comfort, sport and lowered seat still in stock at the BMW dealer, as well as four different handlebars. In case that your legs are somewhat shorter, the lowest seat reduces the seat height to only 760 mm ! If you had to ride a chopper until now, you may find an alternative here. The center of gravity is quite low, this makes for good handling. A lift handle helps you to put the bike onto the center stand. In this case the K75 (10/87 and later) and K100 Basic Mark II are your first choice.
In the case of the K100, vibrations are worth mentioning, especially concerning the four valve models. I´ve been told that the vibrations get smoother when the mileage gets higher, but you may experience that yourself. The K75 does not vibrate as the engine is equipped with balance weights.
A disadvantage of the K100 RS is its narrow handlebar (but it is possible to replace it by the “standard” part). In my case, the fingers of the right hand are getting numb after some kilometers. On the other hand, the RT bothers some riders because its windscreen nearly reaches the helmet. Naturally, it is getting quite warm behind any fairing at high temperatures and low speeds. The RS might be a compromise, the rider catches enough wind when he is in an upright position. The fairing-equipped bikes are of course less easy to maintenance (i.e. when you have to remove the front fork). The usual maintenance items such as spark plugs, air filter and fuel injection are well accesible. Anyone who owned a typical four-cylinder will know what I mean.
Repair works can be done easy due to the well thoughtout design - but not often in a do-it-yourself manner. On the other hand, even any Bosch service station may be able to help you (i.e. ignition and injection). Many parts last much longer than those of other bikes. In addition, almost any part is still available at the BMW dealer (although painted parts are in some cases only primer coated). Even keys and locks are available at a reasonable price. Plus, many parts that are available only as “pre-assembled” at the Japanese bike store are available as individual parts at BMW. Prices are mostly reasonable but not really cheap.
How expensive is a K100 or K75 ?
In Germany, prices are start at about 2000 Euro for a worn-out ´83 K100 with 60-150.000 km and going up to about 5000 Euro for a mint K100 RS16V or K100 LT from the last few years of production. A special case is the K1, some people are asking more than 5000 Euro as a collectors piece. Bikes with ABS and catalytic converter are desired, as well as the K100 basic Mk II. In general, a K100 in a good shape with accessories and an acceptable mileage is about 2500-4000 Euro. The K75 as a used bike in Germany is less expensive and has in most cases lower mileage. This applies not to the police bikes which have mileages of 60,000 km and above. In addition, you will have to work on it to make it a civilian street bike again.
What to watch out for ?
For a long time, BMW has tried to solve the generally known problems. Refer to the modifications chapter to get a list of difficulties and solutions. BMW recalled the bikes several times and fixed some problems during maintenance intervals as well. Therefore, a younger bike is generally preferable as most of the problems are related only to older bikes. On the other hand, real bargains may be found most likely within the first series. So, it´s not necessary to ignore a well-maintained ´84 model. The introduction of the K75 series was delayed two years, so most of the problems were fixed prior putting it on the market.
A well-known problem for a couple of years is the proneness of speedometer and tachometer. Some generations of BMW riders are annoyed by steam inside the instrumentation cluster, and the K bikes make no exception. Today, the reason has been identified as a temperature difference between the inside and the outside of the instrument cluster, caused by the instrument cluster light. Some speedometers were exchanged during the warranty time (or later). In addition, the soft rubber suspension of the instruments and some electrical problems caused speedometer failures. As a result, you should ask yourself if the mileage is true. The maintenance booklet might be a reliable source (a replacement of the instruments was often registered). Faulty electronics is often a sign of corrosion or loose connections. One summer afternoon should be time enough to apply contact spray to every connector and check the tightness of connections. It´s a quite normal job on a fifteen year old motorcycle.
Leakages may occur at the combined oil/water pump. A service kit is available, the complete repair can be done for the price of 200 Euro, according to information given by the forum guests. An oil leakage between engine and gearbox or at the shaft drive housing is more expensive, and the final drive may be destroyed due to lack of lubrication. Front fork tubes of the early K100 are prone to leak, the new fork seals aren´t expensive. More expensive are repairs to the driveshaft and clutch connection. This consists of two gears that are connected. Defective engines make a knocking noise. Banging noises that reduce with increased engine temperatures are caused by a defective hydraulic chain tensioner. This tensioner needs to be replaced with the guide rail. Even for this kind of work, all you need to do is remove the engine cover!
Often you will hear of early K100 owner complaining about blue oil clouds when starting the engine. This is not a defect. It is due to the way the engine is mounted. Later BMW installed pistons that eliminated this cosmetic problem.
Otherwise these engines do not burn any oil. Even if BMW allows for 1.5 l of oil per 600 miles. This is an absurd amount never seen in reality. The oil usage for a K100RS 16V and the K1100 is a little higher as the 2 valve versions. About 0.3 l over 600 miles is normal.
An often overlooked part is the fuel filter inside the tank. According to BMW you should change it every 10000 miles. Some have been in there for the life of the bike! This is hard to imagine since it only takes a few minutes and costs less than 10 Euros. Clogged filters can be detected by gasoline heavily spraying and splashing around in the gas tank. Be careful during the change. Make sure that you keep the crack to the top and do not let the dirt get back into the tank. The production date of the filter is on the housing.
The design behind the side covers is only understood once the K100 rider brakes off the latch for the first time. First you need to pull the cover to the outside and then slide it backwards. It is secured on the lower end by a pin. Replacement cost 42 Euro primed. This was changed for the 1986 model year. Early K100 bike have experienced center stand defects. This gets expensive when you have a full fairing. This was remedied in 1984.
When checking out a K bike it is important to look at the fairing, handles, foot pegs, engine covers and exhaust system for possible crashes. Pay attention to cracks and bondo patches around the mirrors. Some K100 RS/RT models were downgraded to standard models after crashes broke the fairing.
Does the VIN end in K100RS or RT? No? That is not allowed since the RS engine was only available with the downdraft fairing.
The stainless steel exhaust system for the two valve engines will last forever. Only the black heat shield may crack. It protects the exhaust system and is not expensive to replace. The mounting of this part was improved for the 1989 model year. A dull exhaust system can be polished easily with basic chrome polish. After market exhaust systems will decrease the output of these bike and not last as long as the factory systems. Used exhaust systems are dirt cheap since they are not needed often. The muffler for the 4 valve model sounds nicer, but it is a one piece design and can not be repaired. It is very difficult to repair vibration related cracks between the exhaust manifold and the muffler.
The K1200 Models:
The newly introduced 1997 RS and 1999 LT models had some initial quality defects. The first long term test for the German “Motorrad” magazine ended in engine failure. The second bike held up much better. The web site of Ruediger Spieler (www.k1200lt.de) reports a moisture issue with the electrical system on the LT and other problems. The Internet forum K1200RS-IG (www.k1200rs.de) reports oil losses at the drive shaft and the engine in the direction of the clutch. First year bikes (1997) had two recalls. The impellers were rubbing against the housing (danger of overheating), the Motronic was programmed incorrectly and resulted in the engine stalling when the throttle was reduced. Adjustment screws for the brake cylinder and the clutch lever were not secured properly. I suggest you look for later models.
One piece of advice for K-Model buyers: The previous owner promises that he did all the recommended maintenance work himself? Maybe he can lend you the CO-tester, specialty toolset and synchro tester too. He may have been able to change the oil and the spark plugs but that is about it. This is not a R25 that can be maintained with toolkit tools. It is not the worst thing to drop off your bike at the shop every now and then. Certain things are left to the pros with these bikes.
How long does a K last?
Just as with cars, you can assume that these bikes will last 60-250k miles. Clutch and chain tensioner may need to be replaced earlier but should last 50k miles. The transmission should last for ever just like with small cars. Most important is regular maintenance and proper warming up of the engine. Here you have to see how much you trust the previous owner. Most K bikes were taken care of properly due to the high purchase price and age of the buyer. The K100 buyer has a lower average age than other K bike buyers.
What options are desirable ?
If you want extras, buy a bike with the extras already on it. Aftermarket equipment is rare and used BMW extras are not available often and not for little money. Most K bikes were sold with cases. This does not increase the price of a used bike, but new ones are 600 Euros. The hazard lights was a BMW specialty and can be added afterwards for 21 Euros. Another popular option were heated handles. They can be added for 180 Euros. You can also add a luggage rack in the back but you will need to drill holes (40 Euros). Sporty options like wide rims, sports suspension and bugspoiler (RS) can be had for a lot of money. RT riders love to get their hands on the original LT radio. It is commanding large amounts of money. Two options are hard to add later: The longer gear ratio available on the K100 RS and the digital clock that needed to be ordered as an extra for the base model. Most of them do not work on used K bikes. Another rare extra was a 30 Ah battery (compared to 20 Ah). Later K75/100 models were built with 25 Ah batteries standard (K1100 from 1993 19Ah). For the two valve versions you can get an unregulated CAT for 680 Euro including exhaust/muffler.
The first inspection after the purchase
It doesn’t matter how much you like to clean. There is no better way to get to know your new bike than cleaning it with a rag. That is the only way to find hidden corners and possible defects you might have missed during the first inspection. Now follows the important question: Who should maintain the bike? I am not talking about oil, plugs and air filter changes. I mean the tuning of the fuel injection and such. If you plan on having a shop perform the maintenance, make an appointment and have the bike tuned. This will give you and adequate starting point for your future 6000 mile service intervals.
The do-it-yourselfers need to go shopping first! You need a repair booklet and the special oil filter wrench. You also need a special tool to adjust the valve clearance on the two valve models. The shop should do the adjustments for the 4 valve versions. Normal tools should do the trick for almost anything else. Pay attention to two things: the wiring and the rubber parts. After about a decade electrical connections corrode. You can help yourself with a can of contact spray and di-electric grease. Rubber and plastic parts will dry out over time. Check the intake parts, the rubber radiator hoses and the brake lines.
Where do I find my used K bike.
We have a free classifieds section here and dealers and the internet are great sources for used K bike.