I have a 85 K100RS that I picked up as a basket case(literally). I have finally gotten it running. The eng seems fine mechanically but I have a loud knocking noise from the upper rh part of the clutch housing,around the alt, worse when cold,somewaht less noisey whem warmed up, it goes away completely if you raise the idle slightly. The bike has approx 38k. Any ideas as what I should start to look for?

It's certainly the alternator itself.
Remove it and try to run the engine. (It's only 3 screws)

I will give that a try this evening.
Thanks

I'm not that lucky,alt removed,noise still there. Any other suggestions?

Yes a bad one....

The output shaft rivets.

That what I was just thinking, I really did not want to have to pull the engine. I will have to digest this for awhile.
Thanks

Is a output shaft from a 83 K100 the same??

you mean this on ebay

output shaft get changed in 89

Yes it will fit.
Grab it as this is the cheapest that I ever saw.

I bought (unfortunately 6 rivets) ouput shaft in very good condition last week. It costed 123 PLN (41 USD)

I hunt for 12 rivets now... I prefer to set up a more secure part

Well, I have the part from the 83 coming.Since the wife is out of town and I'm retired I'll start taking the old girl apart tomorrow and wait for the replacement part to arrive.
Thanks for all the input

Well I bit the bullet and pulled the engine(6 hours). I'll have to have a neighbor help me lift it on my work bench when he gets home. Good news so far no spline wear, bad news I'll need a new clutch disc(almost on the rivets) but better to find out now than on a trip somewhere.
I'll advise you guys when I get the lower crankcase cover off.

Hi, I bought a new clutch disk, for 86 k100 and it there wasn't much more meat over the rivets than the old one, but I wanted new splines .

Brian

Where did you buy the disc and how much was it?

I bought the disk from Bobs BMW I like dealing with them, they ship right away. you should measure yours to see what it is compared to the specs. I think it cost 140.00 alot but I wanted new splines. see my post for clutch spline problems on the bmw moa site.

Brian

10-4

Well output shaft out,slight wiggle from rivets,just enough to make oil move, needle bearing ok on frt end,large bearing on rear of shaft toast,very rough running,absorber spring has elongated hole. Orderd o-rings and bearing and new clutch and absorber spring, parts to be here Fri. It looks like one of the rivets was catching on the edge of the asorber gear, it had shiny marks on the side toward the shaft.

good work!

Thanks guys, I would have been lost without this forum!!

Interesting, rear bearing shagged, wonder why/how that happened ? What do you intend to do about the loose rivets ? I once read where a guy (Rob Lentini I think, MOA forum) said he placed the output shaft on an anvil and smacked the rivets to compress and tighten them. Wouldn't work if they were too far gone and the holes were elongated though. Or are you purchasing another output shaft ? I have an '88 engine with the same problem (now removed from my bike and replaced with an 89 engine). I'd like to fix the 88 output shaft but have been told that the rivets are removed by using spark erosion. Any inside info would be appreciated as I'd like to fix this sucker, I've also contemplated converting it to a 12 rivet assembly myself, by installing the extra 6 after precision boring the holes in a milling machine (slot drill). Take a bit of work but I reckon it could be done.

The bearing surprised me also,it's the orginal FAG German brand but it's toast. I have a used 6 rivet coming but if it's in the same shape as the one I have I will rebrad the rivets myself. They are just slightly loose. I think most of my noise was from the worn out rear absorber spring. I checked the price on a 12 brad unit at my local dealer and he said 459.00 list but he would sell it for 375.00, still too rich for me.

I bought a new clutch from a German place a short while ago. It was 50Euro Approx $75 and quite good. Uwe Meyer is the guys name www.meyer-bikes.com
I have bought a few things and all were good and quick delivery but there were some things he couldn't supply.

chrish8846 wrote:Well output shaft out,slight wiggle from rivets,just enough to make oil move, needle bearing ok on frt end,large bearing on rear of shaft toast,very rough running,absorber spring has elongated hole. Orderd o-rings and bearing and new clutch and absorber spring, parts to be here Fri. It looks like one of the rivets was catching on the edge of the asorber gear, it had shiny marks on the side toward the shaft.

good work chris

Thanks fellas, I hope to have everything back together the 1st of next week,wife back home today from business trip so other things get higher priority.
I'll bookmark Meyers site

Just a note for all us DIY people, while i was cleaning the throttle bodies I noticed that they did not seem to sit completely flat. I checked them on a machinist block that i had purchased several yeras ago for my wife to wedge her clay on(she liked the hard surface and the height of the stand that someone had made for the block). There was a .010 or so difference in the bottoms of the carb bodies. I loosed all the screws on the bar and retighten them and everything is nice and flat now. I had not noticed any binding but I'm sure the work better level.

Well, used outshaft was much worse that what I have . I took my orginal output shaft and a large center punch and expanded the rivets in the orginal holes after supporting the underside and then took a round piece of steel I had sitting around to support the head of the brad and then whacked the other end of the rivet with a flat punch and a ballpeen hammer and got a nice mushroom shape on the end of the rivet.I was surprised how soft the rivets themselves were.
I will start putting everything back today and let you guys know it turns out.
FYI to yankeeone the old disc was 4.8mm and the new only measures 5.5mm

This is very interesting, it sounds as though you have done similar to what I read somewhere a couple of years back on another forum, very good. This now leads me to think it may be possible to actually machine tho original rivets out then oversize the holes and fit new oversized rivets. Interesting to see if anyone has tried it. I'll be removing my old output shaft from my spare engine in the coming months (winter in Tassie), for a reconditioning project, we'll see.

oh ! chris ...let me get this straight.... you are going to just repeen the rivetts so they mate up tight ?

gooly gosh this could be a problem .

the rivetts rely on their "sheer strength" of a close fit between the hole and the rivett width , which should be a close a fitt as possible .
having elongated holes from wear , you would only be compressing the rivett clamp action again and under load you would find the rivetts would soon be making noise and movement really quickly .

it would be verry adviseable that, now that you have the problem ..in hand so to speak that you re-drill the rivett holes to get rid of the elongated hole issue ...maybe a hole just slightly bigger than the elongation of the ones you have already .. this would be totally dependant of you finding some "stock"/metal to replace the rivetts with a width of the hole that you need to drill to remove the elongated hole ...worst case solution would be to buy/get some new rivetts so that the metal is new ...not anealed and worn at the critcal joint interface .
i know repeening the rivetts would compress/distort the metal sufficiently to hopefully take up the gap ...but not an ideal solution

in my mind, if you had one "thou" of gap difference between the rivett and hole thickness/width ....that would be way too much

You want to do the job right... Check this. This is in German, but scroll down and check what this guy did. This is professional work.
Apparently, Harley Davidson is using the same type of rivets. If the original ones are 6mm and the Harley are 1/4" (6.35mm) this may solve your problem.

CF

Ugh. I think have the same problem on my 85 RS. I have a clunk that seems to come from the alt/clutch area. It happens most noticeably at low rpms -maybe up until about 3000 then I don't notice it. When it clunks, the revs drop considerably as if something is binding. Looks like I'll be pulling the rear end off then tearing into the lower end to see what I can find.

Red

Before you go too far it pays to check out the cush drive of the alternator if the rubbers are worn out it makes a terrible terminal sounding noise and is cheap as chips to fix. How do I know I got caught and had the thing half apart when my brother started laughing and showed me.

K Freak wrote:Before you go too far it pays to check out the cush drive of the alternator if the rubbers are worn out it makes a terrible terminal sounding noise and is cheap as chips to fix. How do I know I got caught and had the thing half apart when my brother started laughing and showed me.

I wish this were the case. I have the alternator out & the noise persists.

Guys, I'm afraid Charlie is correct in his post above regarding the principle of the output shaft rivetted connection. When the rivets are inserted the operation of peining them in fact compresses the shank and totally fills the void space that surrounds the shank. So the joint ends up with a very high clamping force as well as an extremely strong fixation in shear. Any re-work needs to take these principles into account.
Obviously the design with 6 rivets, coupled with a good old on-off the throttle thrashing by the local constabulary (Coppers in Aus) is enough to work the joint loose, hence the 12 rivet design in late '89 (I think).
As mentioned earlier, I intend to have a crack at a loose assembly on my "spare" engine over the winter. I have access to a milling machine and lathe, so I'll be looking to make a solution one way or another. Will provide a post on the subject then.

I think you guys are thinking that the rivets and holes are in much worse shape than they are, there is barely any noticable play in the rivets,just enough to be able to see the oil that is still on the drum move, I can't really feel any movement in the gear, so that is why I was going to go with my aformentiond repair.
I have another question about mounting the absorber spring,the manual says that you need a special tool to mount the gear, it looks like to me that you can catch the pins and just snap the rear of the absorber gear down on the putput shaft drum, is it tougher that this??

I have just pulled my alternator/starter drive housing and have found that I have around 4-5 mm lateral movement of my countershaft. I can push and pull it to make quite a rattle!!

Could this be a cause of the rattle. I have gone all the way into my rivets as well and they appear to be fine.

One of the links on this forum sends you to someone who did a beautiful med green bike and the alt bearing was where his noise was coming from.
By the way when I installed the new absorber spring it had much more tension than the spring I replaced even though it was much thinner.
It's going back in the frame today, I'll let you guys know how it goes .

I was just reading that the very original absorber spring (83-84) was replaced with a newer model providing less tension.
This was the problem of the early K100 as the pin on the gear and the hole in the spring were prematurely wearing off.

CF

I would be very mindful not to dismiss the loose rivets as the problem. The first stages of failure (looseness) will not be immediately obvious or visible to the naked eye, as the failure starts off as radial movement only, even though there is still considerable clamping force across the joint. An experienced parts seller in Brisbane advised me that the first check is to secure the assembly in a vice then apply considerable torque across the joint and watch for movement. By the time the whole thing is flogged out there will be a knocking that is really evident on rapid acceleration from idle (quick blip of the throttle), and it cannot be silenced by increasing the idle speed (to 1050 rpm).
On the backlash eliminator assembly, there needs to be quite some gear tooth misalignment when the new spring is fitted and the thin gear will need to be forced into alignment with the mating gear and clamped there with vice grips or similar. If this assembly is slack then the result will be a gnashing sound on engine back-off, especially when cold and changing gears, and also this sound will be evident up to approx 2500 rpm under load.
To summarise - be very thorough when examining the assembly as you have gone to considerable effort to get in there and it will be annoying if the noise persists after all the work. 'Hope this helps, Dennis.

Well boys she's all back together and I have no noise, sorry it took so long to up date but doing everything by yourseft makes things go slowly. When I installed the new clutch I flipped the engine on it's nose after putting a towel on the floor and installed the trans straight down then went back and tightend the pressure plate bolts and it slipped right back in.
When inspecting things on disassembly I also found that some previous owner had monkeyed with the throttle plate set screws. I have seen several posts on here about how finicky they are to set so I thought what can I do to make this easier? I finally decieded to tie strap the throttle open and check the amount that the flats of the plates were open relative to the side of the throtttle body.As you can guess the the screw that someone had fooled with had 2 blades way off. It was very fiddly to reset them as when you move one it changed two more but I finally got them all open the same amount.
Bike seems to run and idle fine, I will test ride it today and let you guys know how she goes.

Bike runs and rides fine,no leaks or funny noises, I have only put about then 10 miles on the bike since I got it and it had been sitting for about 2 years in a very salty invironment. I replaced the plugs and wires(plugs are correct resistance), cleaned all the connectors and bike runs well, it does have a small problem and that is when it is warm and running it will misfire on 1 cyclinder about every 3-4 minutes, only once and then runs fine again, i'm thinking that with more riding that this will go away.

A good job well done just worth a check that the plug cap is properly clipped onto the little screw on barrel shaped spark plug top. The tip from TWB about using a bit of hose on the tab of the cap to just touch the cover plate is inspired and makes sure the caps cannot come loose.
Regards,
K-BIKE

Thanks, I'll check that.