'85 K100RT, Opinions Requested...

Hello All,

I have a friend who is considering the purchase of a 1985 K100RT with approximately 20K miles. He's owned airheads in the past, and even recently had a K1200RS, 2002 model I think.

He's not a member of BMWMOA. I'm helping him out a bit here, plus learning for my own experience during the process.

Question: Any major issues with 85 K100's? Anything to look out for? Any upgrades that would be considered a "must"?

Let me know, thanks!

Paging Don...paging Don...

If he's around six feet tall or more, his knees will hit the fairing which gets real uncomfortable after just a little bit of riding. BMW eventually fixed this problem but I know it existed on the 85 model because I had one many years ago. Drove me nuts.

This would be a useful page for him to read: http://www.ibmwr.org/ktech.shtml

1985 K100rt

I purchased a 1985 K100RT this past summer. This was my first experience with a K bike having ridden mostly boxer twins. Here are a few observations:

- the bike puts out a lot of heat. My intention was to ride it mainly in the colder months. I find it unrideable in the summer.

- my legs were pushed up against the fairing (34" inseam). I found a used corbin sport seat which moved me back a little an gave a little more leg room

- I love the engine compared to the 1150R/GS but it won't compare to a K1200RS if he has experience on that bike. It is very "buzzy".

- it will seem a bit top-heavy compared to the K12RS

- make sure the tires are less than two years old. I didn't and ended up low-siding on a rainy day, lesson learned.

- the following site provides some good background on the bike:
http://www.flyingbrick.de/GB/home__gb_.html

The 85s are somewhat unique and have some unique parts. Bodywork, cams and some other stuff I haven't paid attention to are different.

I also got an 85 k100rs, but only a month of 2 ago. I have a 34 inseem, and my knees do not hit the fairing. I do have the corbin seat.

There is a buzz in the handlebars, which was annoying at first, as I was not expecting it. But it fades from you consciousness right away.

As for Mods, I have no idea what a stock seat is like, and honestly have not had the bike long enough to what something. It already had the extra lights, heated grips, and tank bag. At least the lights and grips i would recommend.

Things to consider

I have had my 85 for a little over a year and about 13K miles. Here are a few things that I have found out. Mileage on mine today is 55,315.

1) Don Eilenberger(spelling?) has whole page of things to look for listed in the tech pages referenced by scjack.

2) Yes the fairing will hit you knees if your inseam is 32" or greater.

3) Seat height: the same 32" inseam will be able to just barely flat foot on level ground. This is with stock suspension.

4) If he is going to be doing some serious long haul riding he will always be looking for a 6th gear.

5) To the best of my knowledge the seat, gas tank, & final drive are exclusive to this model year.

6) The engine generates some foot peg buzz around 4,000 RPM which is 55-60 MPH.

7) Passenger can not see over the driver. Anoying for the passenger.

8) Yes they generate heat up into the cockpit around town. I haven't had much trouble when riding in the country.

9) At this age of bike he may be looking at some dried out rubber components. I found two of the throttle body mounts were dried out and cracked.


Pluses:

1) Bike handles well for a 20 yr old machine.

2) Parts are still readily available.

3) Valve adjustments are very simple compared to the 4-valve K's.

4) Great all around ride if you don't get stuck in traffic on a real hot day.

5) Fairing does a good job of protecting the rider.

6) I like the dual fuel indicator lights. On trips the 7 liter warning gives me a heads up and the 4 liter says get your butt headed for a gas station.

7) Mileage over 10k miles is 43.3 MPG. 70-80% of this would be over the road miles.

If Beemer would make another bike with the low end torque of these old bikes and a seating position in the upright position I would buy one.

My $.02 worth

I would drain and check the transmission and final drive for chunks of metal. I strongly second the inspection of rubber parts. I have an '88 K100 and have replaced a lot of rubber components lately. This bike may not actually have the 20K as indicated. The well known speedo woes of the K's may have caused it to die for 10,000 miles and suddenly get jarred back into operation. Most of this depends on how well you know/trust the previous owner.

Thanks, Folks!

Great info and links, very much appreciated!

The guy is really looking at this K100 as a 1-up machine for when he wants to hit the road by himself. He's got a new HD Electraglide Ultra for his touring needs. This would be more of an "around town" bike.

Brad, about five years ago I bought a '85 K100RT with 40.000 miles on it. I ran the odo up to ~ 80,000 over the next 3 years. I second all the comments posted so far.

The heat issue can be solved with a few bucks and some ingenuity (Baker Air Wings, Mustang tank cover and automotive weather seal intended for a trunk wedged between the fairing and the tank. In the winter I pulled the seal out - instant heater!)

The early K100s are marvelous bikes, despite their idiosyncracies. HOWEVER, the RT is a touring bike, best suited for long haul, open road and open throttle travel. You can't really appreciate the virtues of the K-RT until after the first 500 miles of a 600 + mile day. If your friend only uses the bike for around town use, it will never be in its element and he will be likely to find it disappointing.

He's also looking at a 20 year old bike with far to few miles on it (my K engine didn't smooth out till I had over 50 thousand on it). That bike has spent a whole lot of time just sitting around. The previously stated concerns about deteriorating rubber are right on target. He may be acquiring a bit of a project bike - the sort of bike that requires dedication.

Steve

knary said:

Paging Don...paging Don...

Click to expand...

Hmm.. been busy with other things lately..

Everyone is right on target.. There is a page I wrote on things to look for on buying a used '85 K - on the IBMWR tech pages. I won't repeat what I wrote there.

I will stress I don't think of the K100RT as a summer bike. Some run hotter than others - and it's not clear why. Even with identical heat sealing. There were times riding it in the summer when I thought I would DIE from the heat.

It was a wonderful winter and bad weather bike. The fairing that keeps any vestige of fresh air from you (especially if you're my height) will also keep rain away from you quite effectively if you keep moving over 30mph. It blows right up and over you.

The mileage on it is very suspect. I doubt very much if any '85 K bike still has the original instrument pod. Look at the brake pedal. If all the nubbies on it are still sharp and look the same - it may have the 20k on it. The front/outside corner ones start to smooth off at about 40,000 miles. They are noticeably smooth at 60,000. The rest of the pedal starts smoothing off a bit at around 80,000, and the outside front corner ones will be flattened off at around 100,000. YMMV on this - but it's more accurate than the odometer on any used '85 K bike.

The other advantage to them - they are frequently found for VERY cheap.. less than $2,000 now, which is a bargain for a litre bike. They will last a very very long time so your cost per mile is low.

That said - I have a K75S now - and would not go back. All around for me - the K75S is a much more enjoyable bike to ride.

Best,