K100 Notes and Stuff (known problems, tips, etc) I've owned two '85 K100RS bikes and loved them both. One was high-mileage and the other was low. The high-mileage one obviously had a lot of things that needed replacing, but what surprised me was how often the low-mileage one broke down as well. The problem was that although there were few miles, the bike was 15 years old and a lot of the plastic and rubber components, especially pressurized lines, were starting to age, crack, and fail. I had to replace several fuel lines, two brake lines, and a wiring harness. Also, the fusebox had some bad contacts in it I had to resolder. All of this was time-consuming but not really costly. The high-mileage bike OTOH, was costly. I needed to replace the fuel pump ($550), all three brake rotors ($200 each!), a coil, fork seals, and a myriad of other things that I can't remember that had just plain worn out. After three years of costly repair, I added up the reciepts and realized I could have just bought a newer K1100RS for about the same money. The guy who bought that bike from me, however, now has a reliable bike with a lot of new parts! --Mike ==== also ==== 1. Don't count on the 60k miles - most, if not every, '85 K has had it's speedo/instrument pod fixed or replaced at least once. Look for service records so you can track the actual mileage.. or look at the wear on the brake pedal and let me know what you see. 2. Splines - the driveshaft splines are the problem point. Very few K100's have experienced clutch spline problems, although it is a good idea to lube them every other year or so.. in the K tech-FAQ there is a writeup on how to easily lube the driveshaft splines - also good for inspecting them. They have to be clean to be inspected (unless they are absolute trash) - look for irregular wear of the sides (ramps) of the splines.. steps in the ramp are wear. 3. Exhaust really isn't a problem.. some of the heat shields rattle, wear ear plugs or take it off or get aftermarket exhaust. 4. Look at the centerstand - if the triangular reinforcement on it is welded all the way around (to the cross-bar) - it is due to be replaced. BMW will still replace these for free if you have a friendly dealer and ask real nice. They eventually break, dumping the bike on it's side. 5. Look at the throttle cable - if the adjuster for it is about 10-12" down from the throttle - it also qualifies for a free BMW replacement. The new ones have the adjuster on the throttle body fitting. The old ones tended to stick, which can be a bit unnerving at times. 6. Check the rear mount on the tank. I've heard of ones cracking where the tang is welded to the rear edge of the tank. Not 'common' but not unknown. BMW came out with a different mount in 1986.. 7. Ignore the idiot fuel lights. You'll disconnect them and put a Fuel+ in when you're redoing the instrument pod (and "when" was intentional - it's not an "if" thing..) Other than that - it should pull like a 1000cc bike, and just check for warped rotors (pulsing when braking) and that there isn't a lot of wobble in the steering at 35MPH with hands off the bars.. (most of them do this - and it is mostly correctable with some careful adjustment of the steering head bearings). Look for service records. They're a good thing. It should idle smoothly at 800-1,100 RPM. A slight rattle from the right side of the engine is 'normal'.. Unless the suspension has been updated, figure the stock shock is trash (allocate $300-$1,100 for a replacement - price reflects the quality of the results.. even the $300 one is lots better than a sacked stocker), and the front end probably could use a fresh set of springs and some new oil.. Other than that - they're a K bike - the Maytag of BMW's.. HTH Don Eilenberger, Spring Lk Hts, NJ JMP#1 === also === I have an 85 KRS. The biggest thing you have with these bikes are age. previous owners maintance records are key. I've had mine for two years. I've only done a few "repairs" - rear main seal - oil/water pump replacement - rear brake pads - rear brake master cylinder The rest of it has been prevantive - spline lube - upgraded electrical grounds - replaced all coolant hoses - replaced all fuel lines - about to do brake lines - rebuilding the works performance shock - replaced oil sight glass - replaced a bunch of the little rubber bits/pieces I have about 67K on mine. Basically remember you're looking at a 16 old bike and what you save on initial buy in will cost you on the other side with some upkeep. Luckily I've met some people on the list who live in the Chicago area that have been willing to help me with these procedures. take care, Shaun Sartin Aurora, IL ==== also ==== The 85's were not subject to the spline problems of later models. The 85's had a few kinks in the first year but BMW took care of them as warranty/upgrades so I would imagine this bike has had them. The most expensive was the speedometer which would start failing after a year or so. Another problem on some 85's was the rear fuel tank was mounted with a single tab. The stress and vibration on this tab would cause a fracture into the tank causing it to leak. This is usually found on the unfaired K100's as the faired ones were recalled to have an insulation blanket installed under the tank and this insulation between the tank and frame backbone relieved the stress on the rear tank mounting tab. I had an 85 K100 for 70k miles and I did have to replace the gas tank and eventually got an upgraded speedometer from BMW at no cost. Other fixes were a new centerstand (originals would break), redesigned gas cap, and ignition control unit. These fixes came out right after the bikes came out so I would imagine all of them would have been upgraded. Jay Wassal ==== also ==== The '85 K isn't known for clutch spline problems, I've only heard of one having the problem.. (and I know lots of people who own them). As with all K bikes - there is a good possibility that the driveshaft splines may have been neglected and need attention (and possible replacement) >Are there any other issues or problems not mentioned in the K-Bike Buying >guide? >(url: http://verrill.com/moto/kbikebuyingguide.htm ) Dunno.. would have to go study it - which isn't possible at the moment (work).. Common flaws: 1. Instrument cluster failures - probably 80% of the bikes. If it works now - it may have been repaired or replaced. 2. Fuel indicator lights - never worked. Take the bulbs out and spend $200 for a Fuel+ Common maintenance needs: 1. It's a 16-17 year old bike. At that age boys need rubbers - so does the K bike. Expect to replace most rubber components on the bike eventually - the clutch basket O ring IS shot, the rear-main seal may or may not be leaking, the mounts for the throttle bodies to the head are or will be leaking shortly, and all fuel lines should be replaced (and perhaps brake lines) as a matter of course. It is an OLD bike.. they age just like people and cars. Luckily a K bike is easier to work on than either of the others.. 2. Lubes - figure on doing clutch spline lube (while replacing the leaking seals) and driveshaft lube (ditto) 3. Brakes - check for leaks - the cylinders are also getting old and if the fluid wasn't maintained correctly (complete flush every 2 years or more frequently) - you'll need new ones. Luckily the calipers rarely seem to fail - even with lots of abuse. New master cylinders will set you back $300 or so for both. 4. Tires - obviously want new.. That's about it - if you read the FAQ's you'll find lots of great writeups on doing this stuff.. figure if someone wrote it up there was a need to do it.. Don Eilenberger, Spring Lk Hts ==== also ==== Only serious if these services haven't been done. Dry clutch splines can eat up both the clutch disk and the tranny input shaft. That's *really* expensive to fix. Usually (but not always) rough shifting and/or an abrupt clutch engagement are good indications of dry splines. You should inquire if/when these were done last. If never, then they should be. You should check on dealer prices to do the clutch splines - it could be several hundred dollars. Once done you won't have to worry about it for a long time, but it's another part of the total cost of the bike. I just got my first K-bike a couple of months ago, but really like it. Very solid, fast, smooth, and refined. Much nicer than I expected. I have a friend in Chicago who has had a *lot* of experience with K's, and he swears the engine is good for 200,000 to 300,000 miles with reasonable care. ... Greg Feeler ==== also ==== >I know many of the K-bikes have 'issues' with spline lubrication. Is this >one of those models? > >Are there any other issues or problems not mentioned in the K-Bike Buying >guide? >(url: http://verrill.com/moto/kbikebuyingguide.htm ) > >Thanks in advance! > >Will There's no "issue" - they just need the clutch and drive shaft splines lubed periodically. Some say the clutch every 40,000 and the drive shaft every 20,000. Some will say more often - you will get different opinions. The clutch is a big job and most would have the dealer do it. The drive shaft splines are easy for someone with average mechanical experience. I believe this schedual is good for all the K100 models, with the 1100's (or maybe the late 100's) supposedly have a hardened transmission input shaft that reduces the frequency of the spline lube (but does not eliminate it). There were updates in that period to add insulation under the tank to avoid vapor lock. If this bike doesn't have it installed, it's easy to do. I'd better stop before I tell you more than I know. But, I belive you'll really like the bike. ==== also ==== >Not a BMW rider yet, just been lurking for the past month. I found a >(hopefully) nice K100 for sale, 1985 model, 80-someodd thousand miles, >dealer serviced, etc. Will, what you have is known (on the BMW list) as a Finest Year K (FYK): this was the year everything seemed to be right. Aftre this, "improvements" took off the egde just a bit (until the 16-valve bikes). At 80k miles, you have an engine that is properly run in. There are examples of these bikes with 200k or more. It is a heavy bike, especially in town, but this all evaporates at highway speeds. As you are in the US (I guess) your highway speeds are lower than mine but the long-distance highway is its forte. Along with some of the heaviness, there are sometimes problems with vibration: some of us think this is part of the character but it does numb the extremities sometimes. > >I know many of the K-bikes have 'issues' with spline lubrication. Is this >one of those models? Issue? Not if you keep it regularly maintained. This is my third K and no problems in this area at all. If you do not know if (or cannot ascertain that) the lube has been done recently, it may be prudent to have it done. >Are there any other issues or problems not mentioned in the K-Bike Buying >guide? A man who reads the FAQs. Like any older machine bits wear out: rubber always deteriorates, and not just that in the tyres. Wiring (under the tank) especially has a life limit, and this may depend on the climate/usage. The great pleasure for me is to be able to go out in the morning, look at the oil-sight glass, kick the tyres and ride 1,000 kms (with stops for fuel of course). -- Graham K. Rogers Bangkok, THAILAND ==== also ==== the 1985 k100rs is called the finest year as joke surely! - annoying twin light reserve not as accurate as later float arm type - heavy steel seat base, prone to rusting, later nylon - grab handles can't be grabbed, later can - engine output shaft bearing can fail due to too strong circlip - rubber mounted footpegs vibrate more - exhaust heat shield vibrates off - weak design in twistgrip gearing, more expensive to replace - accelerator cable slack adjustment not at bar end - engine bars may be hard mounted to sump, ripping it out in a crash - weakest centre-stand design of k range - questionable combatability with unleaded fuels - lots of extra weight over later models, compare fairing trim to k1100rs - unneccesary 2 stage advance curve, generally disconnected by now - and lots of other minor details fixed in later models against this some say the 85 got a slightly hotter cam, well maybe in america, and i've never met anyone who could tell me they could feel the difference most people would agree that the last of any model is the most sorted, so for a 2 valve k100rs that would be a 1989 model, preferably with abs eric ==== also ==== This will give you a grounding in K bike tech.. Specifics to an '85 (and not RT specific): 1. Heat-shield on exhaust will probably rattle 2. Mileage on odometer is bogus unless supporting documents are available (like service records). The speedo *has* been repaired or replaced under warranty. Plan on doing the additional work on it outlined in the K-tech-pages. 3. Throttle-cable - if the adjuster is about 8" down the cable from where it enters the twist-grip - it should be replaced (for free by BMW) 4. Centerstand - if the triangular reinforcing piece on the foot pedal is welded all the way around - eventually the stand WILL break - tossing the bike on it's side. If it is open at each end - it has been replaced with the newer design already. 5. Mid-year '85 update to the K100 (and retrofitted to most of them) involved new footpeg mounting plates which are SOLID mounted to the transmission. If the ones on it are rubber mounted this update wasn't done. It helped lessen buzz in the left footpeg. 6. Fuel lights probably don't work correctly. Common on '85 model. Cure is to remove them and replace the clock with a Fuel+ (see links page for fuel+ info) 7. There are probably leaks in the clutch area. Bend down, look at the bottom of the clutch housing (bell-housing in my terms, secondary-housing in BMW talk) - there is a hole in the bottom of it - you'll probably see oil around the hole. This means you will want to do a replacement of the rear-main-seal and the clutch-basket-nut O ring. One of our members just completed this and is writing it up. This is a good time to do the spline lubes outlined in the Tech-pages. 8. Consider the possibility that the rear-drive-input shaft and the driveshaft are worn.. not uncommon if they weren't lubed regularly. This can be checked fairly quickly (you DID find this in the tech pages right? Anton's way?) - but it requires disassembly of the swingarm/rear-drive to do so - most owners won't allow this. Factor in about $450 to repair this. 9. Figure the rear shock is garbage - allot $300-900 for a replacement (allotment based on how good a shock you want) 10. Figure you WILL be replacing most of the rubber bits on the engine at one time or another. Figure your own labor if you intend to do it and $100 or so for parts. 11. Check the cooling fan turns. Using your right hand, reach in the gills on the right side of the fairing. Your fingertip should JUST about be able to reach a blade - if it turns fairly freely - the fan is OK. If it is very stiff or frozen - figure $100 for a new fan and about 4-6 hours labor to install it. 12. Look at the brake reservoirs - if you can see the rear one without removing anything - it's the original and will be due for replacement. Is the fluid light-straw colored? If so - good. If darker - then figure the brakes have been neglected. Best case - just need a flushing. Worst case - may need new master cylinders both front and rear (figure $300 or so in parts) since these seem most effected by neglect (failure to do a bi-annual flushing) 13. Look under the front of the engine. *Any* signs of oil or coolant dripping from the lump on the very front means the oil pump or coolant pump seals are kaput. On an '85 I'd recommend replacing the pump as a unit with the newer design. Figure $350 in parts - several hours in labor. That's about it - the list above - and reading the Tech-Pages should give you a good idea of what to look for and ammo in bargaining the price down depending on what you see.. The bike should start easily when cold or hot, and run like a cat with it's tail on fire.. :-) Don Eilenberger, Spring Lk Hts, NJ