I recently purchased an 1988 K100RS. The bike seemed to be in pretty good shape considering it’s age and miles. It has 142k on it now. 1000 of those miles I put on it myself in the first four weeks of ownership. Love the bike like crazy even thought I haven’t owned it for very long.
A couple of weeks ago I was on a trip to see a friend and had the back tire chatter hard on a few downshifts during my ride. I got to my destination and had it chatter really hard while grabbing gears and dogging the brakes to avoid an elderly driver that pulled out in front of me. When I got pulled into the driveway I noticed my rear shock was no longer seaping... but blown out.
We cleaned up the excess oil and rode less aggressively to the next town at which point I noticed I was getting an intermittent clunk with a hard miss. We stopped and got fuel and eased our way back home and it slowly got worse/more frequent. I let it idle for a bit and noticed it seemed to make at least one of the throttle bodies hiss on the miss and made no difference with the clutch engaged or not, in gear or out. First thought was that maybe I took out the u-joint in the mono-lever pivot. But thought I could hear chain noise when it happened too. I have inspected the chain by removing the valve cover. No foreign materials were found. The chain was nice and tight with minimal slack. Oil level is up. The bike cranks over nice and smooth and fires easy. If I don’t have the choke on it will make a lot of chain noise at idle if the rpm’s are too low. Get it to 1000 plus rpm’s it has no noise until it gets slightly warmed up. Then the noise reappears. I have checked the spark plus and plug wires. All seem good. Water tested the plug wires no arcing. Idled it in gear all the way up to fifth. Not gear dependent. I work on cars for a living so diggin into the bike won't bother me. I just don't want to tear apart areas that don't need to be if possible.
I'm really hoping it isn't in the transmission. Actually was hoping for a timinig chain issue.
Anybody have any ideas? All ideas and suggestions will be greatly accepted and will help a lot.
Did you start off this new purchase with a complete change of all the oils and fluids? Plus, idle speed is around 1100 rpm.
Do you have a Clymer manual for it?? If not, most BMW dealers have them in stock.
The guy I bought it from is a SAAB mechnic and pretty uptight over maintenance with his bikes. The fluids were all changed before I picked up the bike. I'm in the process of clening some containers to collect fluids in to see if I have any broken parts come out of the crank case or gear box. My analog tachometer reads a nice even 1100, the cluster tach reads 1200. I have the Clymer manual... I felt it was a must have before I picked up the bike and started riding it.
I planned on pulling the gear box to lube the clutch splines soon due to an occassional hard to downshift situation. Double clutching has worked great but I hope to own the bike for a while so no sense in abusing the clutch or trans. (If I haven't already.)
Sounds like your starting off on the right foot with it.
Check for broken vacuum lines and a lot of basic housekeeping and maintenance.
For instance an oil leak that is thought to be from the clutch can many times be traced to a cracked crankcase vent hose. So, go slowly and methodically on the old girl. Lubing the driveshaft and clutch splines are a great place to start bringing all the maintenance current.
Do not jump at throwing parts at these things. Parts are very expensive and a lot of the time there not needed.
I had a '85 K-bike I just bought cheap and the trans. howled on decel. After flushing the trans. several times with straight 90 weight all the noise went away. So a lot can be said for trying the simple fixes first. A very good trans. and rear drive lube is Mobil I 75-90 gear oil.
Some of the best old K-bike information on the planet can be found here:http://www.ibmwr.org/ktech.shtml
chaos... could it be that simple? I was on that path earlier in the noise diag but second guessed myself due to the noise at the trans and the timing chain. But now after looking at some cut-a-way pictures of the the drivetrain I was coming back to that possibility. I was wondering if a bad u-joint was binding and unloading just like in the front axles of the diesel pick-ups I work on on a daily basis.
I want to lube the clutch points like the Clymer manual says I need to so I will have the perfect oportunity to look into the drive shaft components.
For spline lubricant, you want to use Honda Moly 60 Paste and nothing else. Available at your friendly Honda MC dealer(they use it on Goldwings).
If the bike was from coastal Oregon, keep an eye out for rusty u-joints and such. That dampness will get in everything and even make the engine oil look milky in the sight glass if you just take a few very short runs of just a couple blocks.
I'm sure we will talk about Oregon weather and it's effect on BMW electrical connections and instruments at a later date.
Well it looks like I will have the bike pretty well disassembled this week. I have a battery draw that sucked the life out of the battery, and this miss/clunk/? Maybe they are all related to each other. I will be sure to replace hoses that are questionable when I go through the bike for the draw.
Just talked to the guy I bough the bike from and he said it had been to a local BMW shop to have an ABS concern looked at. He said they had the tank off and some other things off as well.
"Make her fresh and treat her well." is my current motto. the BMW bikes i have ridden have done nothing but drive me to enjoy motorcycle riding more than I have ever before, and I have put between 25k - 30k miles on two wheels by the age of 40. A Jap bike doing this would have prompted a sell at loss. Not this bike... I just look forward to spending more quality time with the bike. (Even if some of that is fixing her.)
Idle rpm is 950 +/- 50 rpm (see owners manual or sticker under the seat.)
Several options for lubing splines:
1 - Honda Moly 60
2 - 50/50 mix of Honda Moly 60 and Wurth 3000. The Wurth SIG 3000 is STICKY stuff that helps the moly stick around longer. (Recommended by Paul Glaves, probably one of the most knowledgeable K bike guys around.)
3 - Guard Dog 525 (also recommended by Paul Glaves.)
Does your Clymer manual say that you can slide back the swingarm and trans. as a unit?
By using long guide bolts in the trans./bellhousing its possible to slide the trans. and swingarm back about 3" or so. Just enough to reach in with a moly-lube coated brush.
Also, after you remove the final drive unit, put a couple of worm-type hose clamps around the driveshaft and pop the circlip-held shaft loose with a couple flat bars against the clamp's screw drives. Don't mar the swingarm flat surfaces. Its soft aluminum.
I doubt the Clymer manual recommends that because, at least as far as I'm concerned, it's a really sloppy way to do things. Most importantly because it does not allow you to clean off the old grease from the transmission input shaft and clutch plate splines. Next, if you don't know what was used before, it's possible that the old grease and new grease may not "play well together."
It's really not that much more work to do it properly.
Following up on Duck's post, you only want to use the "shortened" spline lube technique if you are absolutely sure that all the parts/splines/driveshaft are in good shape. On a new to you bike, preventive is the word....!
And yes those bikes sometimes had the famous BMW leaky clutch O-ring, happened to me, and would have happened soon on my K1200RS if I hadn't done some preventive maintenance :yeow:
To get back to the chain noise, could you have a worn lining on the cam chain tensioner? That also happened to me, the bike was certainly making all sorts of funny noises at idle. Is this an Oil Pressure activated tensioner like the newer bikes? I don't remember, could be interesting to see if the noise coincides with a drop in oil pressure as the engine warms up.dunno:
Here is what Paul Glaves has to say on them pesky splines and their lubrication, page 36 on: :thumb:
Sounds like it started out as your u joints locking up from to much angle ...then your miss fire and "hiss"....you may have a damaged timing chain,tensioner or gear from the lock ups at speed....
As far as the trans and final drive removal.... Clymer sets out the steps in removing the sming arm as a unit then the trans as a unit. They have the bike pretty well disassembled by the time you get to the clutch assembly. Since I work on cars for a living I have been spending this evening eyeballing the bike to get ideas on how to shortcut the total disassembly. I think that with patience and holding my tongue just right I can pull the final drive and trans in one fell swoop. As I see it.... FORD and CHRYSLER both tell us to remove the drive shaft from the rear axle and the t-case. Then remove the t-case from the transmission. Then remove the transmission. I have equiped my transmission jack with an extension that supports the driveshaft and the t-case while still attached to the transmission. If we can do that with a 1 ton pick-up I don't see why I can't rig up a balance plate for my floor jack to pull the trans and final as an assembly with most of the bike still intact. Then I can deal with the final at any point in between.
As far as pulling the assembly back about three inches I might be able to get a set of metric allen head bolts long enough that would act as a guide and a stop all in one. I will check with my local FASTENAL dealer here in town to see. If he can't get anything I can buy steel rod and tap it on one end. I have made guide rods that way before for lining up various components on diesels that are sealed with RTV and no gasket as well as heads and transmissions. It will be a challenge that will be enjoyable to boot.
As you can tell I work on a lot of big components so dealing with clutches that make odd noises and such I have access to some really good high-pressure/high-heat lubricants that meet or exceed what most bike repair shops use. Both FORD and CHRYSLER highly recommend using Molykote on clutch splines and pressure plate diaphragm fingers. We also use a high pressure moly based FTP lube on driveshaft splines in the slip joints. I will do some comparing of the shear pressures and functional temperatures on these as compared to the ones you guys have recommended. Nothing but the best for my girl.
I need to get a hold of my local independent BMW tech. He is straight out of Germany and is a cracker jack when it comes to BMW's. He might have some other ideas to explore, but might only agree totally with what you guys have told me.
All I can say is long live BMW motorcycles and I really love support of the Bimmer communities. Even the nearby BMW Auto and Motorrad dealership's techs have been of great assistance with information and avenues to check out. Never got that with any of my Jap bikes unfortunately.
Will try to have either good news this Saturday, or more questions (hopefully not).
Thanks for all the info. Ride hard, ride safe, and "Grind them into dust!" :teeth
ANYBODY headed to Redmond, Oregon for the BMWMOA gathering this July?
While typing the last entry I was on the phone with my buddy from work that is a gas engine driveability specialist. He had a few quetions for me on a diesel that a friend of his owns, so in turn I squeezed him for some ideas. He is wondering if BAK04GT isn't on to something with a chain of events theory. Guess I will be pulling the front cover and tensioner to get a good look at it for damage. So far I have a lot of leads that are least cost based and then go from there.
I also agree that for the sake of sanity and quality care I will go the route of full removal of the trans. Like I have said before I want to keep this bike for some time and add other bikes to the "BMW collection." (Just the one for right now but have leads on a couple of boxed up but complete R series bikes from the sixties and early seventies.)
This is a common symptom when a vacuum cap has popped off. I suggest you check them as well as syncing the throttle bodies.
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