Mechnical review of the bmw k-bike / K75RT / k75s motorcycle

Audiance: for those that are considering buying them or bought one recently.
Created: 09-13-05 @ 50,000 miles
Updated: 02-04-2009 @ 63,712 miles
In for a penny in for a pound or with the K75 / k100 in for a penny in for many pounds. The K75 is a wonderful bike but the cost of parts and the time required to perform maintenance as the bike ages and the rubber seals need replacing is HUGE. More than I could ever have imagined. I am always hoping and praying to reach "the promised land" where I ride for years without big repairs cycles.

Fall 2007 Repair & Rennovation Cycle: fuel filter, full spline lube with the awesome Honda Moly60 grease + final drive & transmission gear oil. Opened transmission to tighten grub screw on the gear shifter shaft (aka grub bolt) and seal the leaking transmission cover which had no gasket!

full drive line lube with Honda Moly60 grease - the clutch spline & final drive splines were rusted! The bike shifts like a luxury car now!

New steering bearings and races, new upper fork tubes from Forks by Frank for Forking by Frank, new fork gaiters, progressive springs, fork seals, bushings damper piston ring. Honda / Show 5w fork oil.

Full throttle body & injector service replace all rubber o-rings & boots to the plenum, new K&N air filter, cleaned and painted top of motor, Replace all rubber fuel injection lines and relocate fuel pressure regulator outside the fuel rail (thanks to Luke on the Flying Brick forum in Brisbane Australia!!)

New anti-freeze (never use Preston Dex-Cool Dexcool 150K like I did because it caused brown sludge.

Applied di-electric grease to 90% of electrical connection, wrapped wires with new friction tape (cloth electrical tape).

Resealed the timing cover from leaks, the hall effect seal, crank & timing cover - new rubber. Sanded & painted lower fork legs, timing cover, crank & valve covers.

Cleaned a ton of parts. Bike looks and runs awesome. A project like this must be treated as a hobby. Many K's are becomming parts bikes because of the cost of restoring them. I bought the bike for around $3,600 on 11/2002 and have spend around $4000 in parts including tires and some optional add-ons like touring windscreen & handlebars. I perform 99% of the labor myself.
In my opinion these links to the BMW community are unquestionably the best part about owning a BMW.
The Flying Brick Forum (english version of site) Best place to talk with live people and get
same day answeres to your questions from a great bunch of riders all over the world that really
know a ton about the K bike and still ride them actively: Flying Brick Forum (awesome free resource)
The premier BMW repair site & forum:
Internet BMW Riders (Highly respected standard tech resource)

However, is showing signs of age. The K75 was last made in 1996. That means new updated resources are needed to address the changing needs of "Older K bikes" in addition to the classic repairs mentioned on the site. Also, digital camera's were still a novelty pre 2003 when many of the articles were written. In a few cases like steering bearing race removal I found a vastly easier and better method to remove the races with a punch versus fiting with a dremel and risking damage to the steering tube. I have taken tons of digital pictures and am creating edit videos that can be downloaded for free letting the owner see the entire repair. Many of the write-ups can be complex to follow.

Also, there are many needed articles: Timing cover reseal, leaking throttle body boots, fuel injection o-rings, fuel injection rubber line replacement and Pressur Regulartor relocation, PCV vent tube which junks up the air box and plenum and even map sensor with oil mist. Full Radiator fan / thermostat, and hose replacement. Many of these repairs were not needed in the first 12+ years of the bike's life.

The K75 Myth of Invincibility (with proper maintence):
Won't any older japanese bike last forever if you throw between $2000 and $4000 worth of parts at it? Practically, any vehicle will run forever "with proper maintenance".

The Hard Part: For new newer owners was shelling out big bucks. My K75 S for Sport cost around 11,300 w/ ABS (~$2000 option) (USD in 1992!! or close to 18,000 today! (2007 dollars). That is big money for the the bottom of the line starter bike. Then there were all the defects and issues with the smoke from being parked on the side stand, fogging speedometers, warping speedometers, and tons of other stuff. Subtract 50% of the purchase price for depreciation after 5 years. Suppose the next owner pays $9000 in today's dollars and gets hit with a few minor issues and then dumps the bike after after 5 years for 4500 (my friend paid $4600 for a K75RT with a badly leaking RT fork seal and pleanty of other oil leaks that burned on the exhaust when starting. I paid $3600 when my bike was 10 years old. So both the first and second owners get hammered with depreciation. Now as an "older K owner" I have spent $4000 in parts spread over 5 years to restore and improve the bike. So even I have taken a beating. Once you hit 10 years bmw are not easy to get rid of. Especially, the K-bikes because of the labor to do repairs. With any older bmw it is easy to get slammed with repairs totaling thousands of dollars. In for a penny in for a pound. Once your spennd over $1000 on a repair do you really want to put the bike up for sale and loose that thousand you just spent?
The bike is often hailed for being able to last 300K + miles. But this if often soft commuting miles and long trips. When the bike is used like a car for normal trips it needs vastly more frequent repair. The bikes are often sold for parts because the time to do the repairs vastly exceedes the used value. I warn potential or new K owners of this so they can determine if they really want to spend the time and effort to renovate the bike.

I warn them not to believe sellers that say it was always serviced at the dealer. Who has their dealer perform the following maintence required in the book or that is needed even if it is not in the book:

replace rubber brake lines every 5 years (or any time even afer 14 years?)
clean, adjust steering bearings
reseal that leaking timing cover for $389 (bmw dealer 2006 quote)
replace all radiator lines, lube the fan motor (the fan is now $159)
full driveline lube $450 at my dealer using the cheater method
Grease the swing arm bearings before they wear out
fix the chronic leak from the clutch push rod bolt & nut in the middle of the boot in front of the rear tire.
Grease the side and center stand.
Clean & grease the speedometer contacts & install the Sigma BC906 cycle computer as a backup for when the trip meter fails (as the almost all do) Mine failed in summer 2006 @ 53K, my friends K75RT failed 40K in 2000.
reseal that leaking final drive unit ($800 to replace + $289 for a new drive shaft)
Replace those rotors that get thin after 50K ($200 each! + labor)
replace those rusted upper fork tubes ($600 for the tubes alone, my dealer quoted me $1250 (USD 2006)!
What about all the fuel lines, injector orings.
Deal with the PCV oil mess or all the other chronic oil leaks.
clutch, throttle, choke cables - that's can take 2 to 3 hours on a K.
replacing the front and rear master cylinder piston.
Clean the starter armature & install two orings
replace the alternator rubber rotator cup blocks AND the oil seal in front of it.
Valve adjustment & throttle body sync
Fork oil?
Gas Cap: leaks and needs six seal replaced - who does that?
Tires: once they are worn out most older K owners don't even want to pay for that because they know they won't get the money back when they sell the bike.
          A Previous Owner (PO) of my bike scraped the top case and used a paint brush to cover up the scratches. Talk about lazy and cheap.
          The next owner fixed it by removing the top case.
Spark plugs: & oil and filter change and having the dealer install a fuel filter and check / top off all fluids is their idea of a "recent full service at the dealer".
Fuel Injection Cleaner: It should be done every few years especially if the bike sits as many older K's do.
Headlight switch - clean or replace, they all fail from dirt even if you almost never use it.

Cosmetics: replace leaking pannier seals (now $55 each), lube hinges, locks, fix broken straps,
            fix rust, coat nuts and bolts, paint rusted lower grill, water pump. Many owners just remove
            the lower cowling on the K75s & RT because they are too lazy to take it off during oil changes.

Paint: so many 2nd hand K owners (aka flippers) love to take all the plastic off and paint the bike during the winter and then try to sell it in the spring for a profit.
        to make the bike look like it is in good condition even though mechanically it is a nightmare.

The Turnover Cycle: I suspect the original owner bought my bike in 1993 and after 5 or 6 years sold it. Then it changed hands at least three times by 2002

Scared Straight: The guy I bought my bike from put the bike up for sale after about 1 year after getting a $1200 bill in 2002 at the dealer for changing the cluch and he was still having trouble selling the bike.

It is now almost 2008 and many of these parts are on borrowed time regardless of mileage. They can be replaced as they fail but that puts the owner on an endless merry-go-round of expensive and never ending repairs. I average $750/year. Many former owners tout the bikes as so great and trouble free (with proper maintenance) don't own them anymore. I was reluctant to replace fork oil, brake & drive train fluid because I had to face major repairs every year there was little time or energy left over for "luxury items" like replacing the rear shock which was worn even when I bought the bike in 2002.

R, F and K-bike repair tech / repair articles:

Key words: R1100, 1100, boxer, R1150R, R1150G, 1150.

BMWOG bmw owners group but you must pay $35 /yr membership dues to post.

One of the the smoothese motorcycle motors ever made. Almost no vibration in the handle bars. Adaqute power and fairly flat power curve thru the rpm range. Motor can last a long time. Great commuter: hard locking bags work for years with no problems. This bike emphasises comfortable safe riding.

MPG: K75S only gets around 40 (80mph highway) to 45 (70mph highway), K75RT 45-50 mpg.
Epensive parts: Gas tank unpainted/painted $700/$1400, alternator $750, clutch $160 or $850+ installed, drive shaft $300+ final drive $800 = $1100! Speedometer $1500, computer $1200), Transmission $1000 (just for the empty shell!), Main drive shaft and gears $1500!

Designed for the Dealer: The time it takes to perform repairs is excessive and I believe was made unecessarily difficult by the engineers to provide the dealer with enought money to survive. My dealer doesen't sell many bikes. They live on repairs aka service. Dry clutch spline lube anybody?

Initial price of bike: an incrediable $12,000 in 1992!

1. Speedometer by Motometer (Cost: new ~$1500, or ~$500 rebuilt): this was a real customer killer. People bought the bike new and had huge serious problems within the first year of ownership. BMW severed the relationship with Motometer forever - although people that repair the speedometers have told me it really wasn't Motometers fault because they were designed to be enclosed in airplane cockpits. Moisture or water gets in and in time, internal connections separate or get corroded. In the lower Southwest or the South with the sun is extremely intense the gauges w warp causing the needles actually hit the surface below them. The trip meter will not reset this is a real pain since you need it to determine when you need to fill up with gas. BMW only partially corrected these problems. My speedometer needle with sick because the warped faceplate would hit it. I had to Dremel and flatten the faceplate. If the rubber cushions wear out the vibration will destroy both your instrument gauges.

2.) Oil/waterpump unit seal fails - cost me $200 for parts and $40 to install the seal with special tools at the dealer, the rest I did myself!

3.) Alternator: $750 (32amp), luckly I got it reubilt for $105 plus my time to call around and find a place. Why did this fail at 40K? C'mon arent these bike supposed to be plug in heated vest, grips, lights, etc? Also is a very strange repair that you would never figure out on your own because he alternator is direct drive and uses these strange rubber blocks which have to be glued to be held in place during install. This is common we are German engineering. It makes the repair more difficult than it has to be.

4.) Radiator fan & hoses ($150): Almost 3 hrs to replace plus a trip to the dealer.

5.) Spline / Drive shaft: many failed, or fail every 40K - mine hasnsn't - i am super carful with the way I shift, this is not a bike to "beat on". Greasing? Shaft drive should = maintence free (just like cars + most other brands of motorcycles). Isn't bmw supposed to be all about the shaft drive, and the leader in shaft technology on motorcycles?

6.) Dry Clutch: the guy before me spent over $750 for a clutch replacement. That is because bmw uses a weird car like dry clutch that requires 1/2 the bike to be take apart.

7.) Head light switch: fails on most or all of the k-bikes because once again it was desinged wrong:first I cleaned it but it failed again a half-year later. $65 for the part.

8.) SMOKE AT STARTUP: plus a broken center stand: bike must be on the center stand, else you will get blue smoke at start up. How did this happen? Does bmw not know how to design a motor that sits on it's side after decades of making boxer motors??? Most riders put the bike on the center stand which caused it crack and fall over!

9.) GAS TANK LEAK rubber mount replacement ($700 unpainted or $1400 and painted With a decal): the gas tank is aluminum and will never rust but, magnetic tank bags will not stick. Also, when the little rubber mounts wear out the tank contacts the frame and causes stress cracks. JB Weld failed for me because the tank, which is normally NOT pressurized because it is vented by a rubber hose on the bottom right side of the tank, became pressurized because I had kinked the hose after reinstalling the tank by not routing it properly. I removed the tank several times hoping to get it right but I failed. I later observed the following.

After restoring the tank and putting the hose on the metal tube closes to the (there are two connections right next to each other) seperate that hose in the middle where there is a plastic one way flow valve. Leave the valve connected to the lower hose. Now blow a mouth full of air gently into the hose, pinch it tightly and move your face away. When you unpinch the hose you will fill the tank exhale the same pressure you blew in. You can try this before reconnecting the tank as a test to feel flow when you can verify the hose is not kinked at all. When filling gas or taking a short ride stop and turn the bike off and open the tank - if you get an outward blast of gas fumes even an actual mist of gas this is a sign the hose is partly or totally kinked. As the rubber ages the hose hardens and holds (memorizes) its shape better. However, a little noise, from a slight imbalance in air pressure usually a vacuum on my bike is normal. But I digress...

In my opinion this odd hose routing which I have never experienced in any other motorcycle was part of a design philosophy at BMW where you are free to do anything you want to the bike but if you don't do it exactly right then you must be punished. The punishment might be small like breaking a cover or losing it or result in a huge expense. It might happen soon or many miles down the road. In this case the punishment came about a month later. I started to smell gas. I just got the bike and foolishly ignored the problem. Soon gas leaked everywhere - on the wires, melting rubber, staining paint you name it. It took three trips to the welder and $60 to resolve.

Most bikes are made with a steel tanks that can be dented and beat up without leaking. A little icing on the cake the fuel pump failed because if they are not immersed in gasoline they can rust and seize (cost: $300). I almost gave up but I would had to have sold the bike the bike at a huge loss.

11.) Routine maintence: Designed for dealer dependence. I was forced to "learn the hard way" and not ever rider wants to go throught this. Oil chg takes about 40minutes - the fairing is hard to take off and the filter is a mess that was made so you would spend $50-$70 on oil changes. The battery is really weird requiring special tequniques - which i have mastered - I could go on and on. In general, you must learn a lot of weird german stuff that has little or no application to normal non-BMW motorcycles.

12.) Valve adjustment: according to the book is that the 12,000 miles. I went 20,000 and only two exhaust valves were on the tight side. You could easily go 25,000 plus. Spline lubes are a more mysterious matter some people go 80,000 miles with no problem because these bikes are pretty old now I would advise against spending a lot of money unless you hear a noise or want to do it yourself. If it fails you will drop about $500 or more just in parts.

13.) SHIFTER PROBLEM: lesson one, never downshift. I come almost to a complete stop and then click from fifth down to neutral. The transmission design makes it easy to finding neutral spots between gears and requires a long movement of the shift lever. My shift lever had lots of play or "slop" due to a loose grub screw an uncommon problem that requires removing and opening the transmission (repaired 09-2007).

14.) Depreciation: BMW's reputation is that it is expensive to own. Today, September 2005 go to 1990's japanese crusiers selling for around $2,500. In 1992 my k75s w/abs cost $12,000! I would be luckly to get $3,000 even though it is in excellent condition. The older they get the harder they are to sell.

15.) There are many other problems but this is a good general list. This is a long-term investment and you have to be a good wrench and willing to turn it and spend big money on parts.

1992 K75s, 58K miles as of 11-2007