Well,, here is a question  that i hopped i did not have to ask
this winter i did a renovation of the outputshaft in my 84 engine.
the reason is that it had a very loud knocking sound , especially when cold.
so i thougt that  was it.  
It turned out to be a missing fibre washer behind the clutch basket , and also the ball  bearing on the outputshaft was rotating in the housing.
had a spare engine so i could pick the best of the two ,lower enginecase from the spare and the outputshaft from the faulty one was surprisingly the best of the two ,no play in the rivets at all.
ordered new bearings for the outputshaft and alternator drive  also new o-rings all way round.
a couple of weeks ago i got it assembled an fired up ,at first i was thrilled because the k nocking sound  was completely gone .
well at least for a few moments.
now there is a higher pitched  knocking sound ,only between 1300-2100 rpm.
at first i thougt it was something in the alternator area, so took that apart and drove the bike without it ,the sound is still there and didnt change at all.
i did a stetoscope investigation  with a screwdriver and that , to my surprise points directly to the waterpump, it sounds like someone is using a litlle hammer on the inside of the cover.
having a spare i swapped it with that, still no change.
put in a thicker oil yesterday 15/50 instead of 5/40.
And that may have made a slight change , but the noise is still there  

now im all out off good ideas , can someone come up with anythinng.

hoping that im not having to take it all apart again.

best regards 

k-rider

You said that you changed the bearings on the output shaft, but did you also check that the spring sir clip behind the idler gear wasn't worn?

smithy wrote:You said that you changed the bearings on the output shaft, but did you also check that the spring sir clip behind the idler gear wasn't worn?

Ohh forgot to mention ,did change that one too.

k-rider

k-rider wrote:

smithy wrote:You said that you changed the bearings on the output shaft, but did you also check that the spring sir clip behind the idler gear wasn't worn?

Ohh forgot to mention ,did change that one too.

k-rider

And the rubber dampers of course

k-rider

wonder if the water pump shaft is meshed up correctly with the output shaft ...???  or loose impeller ?  just  a thought

You didn't forget the small end bearing retainer C clip

Remembered the circlip, the impeller is fine and not loose .

k-rider

just a question ...isn't the output shaft to water pump mating keyway offset .....

im sure others will remember, better than me


just a thought

Yeah it is and if the shafts don't align the pump wont go onto the engine. Its as close to fool proof as possible.

I am thinking it may be the small roller bearing on the front of the shaft was it replaced.

Yeah it is Charlie, but I don't think the water pump would bolt up if it was wrong. Just wondering if that's the symptoms of an unbalanced clutch ?

yes you are right charlie, it is not possible to put it together the wrong way, however i am thinking of that specifick area to be were the fault is, have anyone got any experiance with that ?    

k-rider

RicK G wrote:Yeah it is and if the shafts don't align the pump wont go onto the engine. Its as close to fool proof as possible.

I am thinking it may be the small roller bearing on the front of the shaft was it replaced.

are you refering to the needle bearing on the outputshaft? 

that was replaced with a new one  as was the big ball bearing in the clutch end

could be smithy

noise travels along the same piece of metal pretty well

that's a real good thought

how much free play is allowed between the oil-water pump shaft and the outputshaft ?

k-rider

When you reassembled the clutch did you grease the wire ring behind the diaphram spring?

smithy wrote:Yeah it is Charlie, but I don't think the water pump would bolt up if it was wrong. Just wondering if that's the symptoms of an unbalanced clutch ?

when i assembled the clutch i did take care to place the colormarks on the clutch assembly in oposite  directions. 
so i dont think that is the proplem


k-rider

RicK G wrote:When you reassembled the clutch did you grease the wire ring behind the diaphram spring?

i did give a very thin smear of grease 

k-rider

That is all it needs. I got caught once with that and it made some very strange noises till it got just a very thin smear and then it was happy and quiet.

one thing that is strange is the very limited  rpm range  of the noise 
dont you think

k-rider

I have a feeling you will be elbows up inside that engine again soon.

That was what made me think of the roller bearing they can be like that when they chatter but I certainly would not expect a new one to do that.

It is strange that the noise is only at that rpm range, I know this sounds silly, but have you tried engaging the clutch at those rpms to see if the noise disappears?

Yes i tried that , still no change

k-rider

Possible slight difference in air bypass screws?  They can get dirty and clogged too, causing a difference in mixture around those RPMs and a slight knocking sound.  I go through every once in awhile and tighten them all the way in (counting the turns in), and then turn them back out to where they were.  It pushes any dirt out of them and equalizes everything.

Rabidchiwawa007 wrote:Possible slight difference in air bypass screws?  They can get dirty and clogged too, causing a difference in mixture around those RPMs and a slight knocking sound.  I go through every once in awhile and tighten them all the way in (counting the turns in), and then turn them back out to where they were.  It pushes any dirt out of them and equalizes everything.

hi Rabidchiwawa007

thought about the tb's but havnt done a sync. because the noise seems to come from the waterpump area, but hey , its surely worth a try ,
thank for reminding me that sometimes it pays of simple (and cheapest ) tings first.


k-rider

Here is an update 
today i just spend 5hours trying to find the source of the knocking, started with dismantling the oilpan to check if the bolts securing the outputshaft bearings 
was still tight .they  was.
then i dismantled the gearbox ,and the clutch to retourqe the big nut on the flywheel, nothing wrong there ,well of it goes to unscrew the intermediate housin,
I then very carefully inspected everything ,and the only thing i could find something wrong with was the sprocket connecting the intermediate shaft and the sprag gear ,the had some strange marks that could make the type of noise when 
sliding against the litlle spring behind the intermediate shaft. 
I replaced them with a spare set and put it all together ,
sigh .... there is still a litlle noise left ,it might have helped ,but i will find out driving
to work on monday .

if there is still no change ,i will just run it till it breaks ,(it probably wont:-D)


K-rider

well i found a good reason for a ride , the bike sounds better , still a litlle noise , but way less than before ,
so time for a litlle celebration  



k-rider

Put some earplugs in and ride till next winter, then sort it out. Oh, and if it breaks, don't call me.

you did replace the spring in the counter backlash gear on the output shaft ?

there is a bmw notice about this process , refitting the retention pin ...drilling a new hole for the spring mount etc

just a heads up

Allready use earplugs,  yes i did replace the spring ,only thing i didnt replace is 
the washer between the bearing and the idle gear , i found out by reading the manual that it should ALWAYS be replaced, now i know what RTFM. Means   
anyways , i dont think this is the culpritt.  

k-rider

The washer between the bearing and the idler gear is a shim which has the
purpose to eliminate the axial play at the idler gear.
This shim you got in four different thickness, in 0,15 mm steps.

If you got the idler gear and absorber housing from different bikes or new parts,
the play should have been measured and the correct shim mounted.

I would guess if you now have a shim that is to thin, it could be the source to
the noise that you now hear.

The washer im talking about dont look like the one in the exploded view in the manual , inge i think you are talking about no.19 .
what i put in is more like a cup washer that gives a spring tension to the idle gear .
i just put it in as it was before i disassemled it .
but i can see that you  ay be right ,as usual. 
Now the question is : should i be worried about this? ??

K-rider

This dished washer was used on the early models, change late -85.
After that shims was used instead...

If you should be worried....if it still was tension in the washer....I don't think so.

On the other hand, BMW did change this design as the dished washer did loose its tension over time.




Here is the dished washer (from CF's rebuild thread).

thats the washer i have used , well i will keep an ear on it  ,if it gets worse i know what to look for ;-)

thanks for all the answers guys.  


k-rider

Good Luck   .

Here is a little update, i might havefound the error , last Thursday on my way to work ,when slowing down after half an hour riding 130km/h ,the engine sounded allitlle funny ,and the the backwheel blocked  
well i pulled over and after a few minuttes i was able to start it and drive it to work and back home .still sounded ugly at low rpm but seemed to run fine above 3000rpm.
back home i pulled the thing apart and found out it was the starter sprag assembly 
grinding its way forward through the engine housing .
the bolt holding the drive dog for the alternator had somehow unscrewed it self  
and YES im a100% sure it was tourqed correctly.
well , today at 9am, soon,  a good friend of mine will arrive with a 1990 engine   that he sourced from somewhere  there is no availleble information on it , so im hoping for the best.

but hey , it should mean 12rivet outputshaft new type spraque cluth and no more blue smoke on start up  .
also im in a bit of a hurry since we have five day trip for the harz mountains in germany , planned from saturday to thursday, so im keeping my fingers crossed .
will update when done :cyclops: 


k-rider

Don't put too much faith into the no smoke on start up My 8/90 K100 was a smoker and the 7/93 K75 is also a smoker along with the K1100. The K75 is the worst by far but they all do it.

RicK G wrote:Don't put too much faith into the no smoke on start up My 8/90 K100 was a smoker and the 7/93 K75 is also a smoker along with the K1100. The K75 is the worst by far but they all do it.

Oh, thougt the piston ring arrangement iliminated that error, well its a small thing that i can live with

k-rider

My theory is that with the valves closed and a cooling engine it will draw some oil down. The pinned rings did help a lot but it certainly didn't solve the problem. Any bike that has horizontal cylinders will do it. The old oil head boxers did it and so do the Honda Goldwings from the left cylinder bank. When I was working for Honda we used to get a lot of complaints about the Goldwings.

Okay ,learned something today   

k-rider

RicK G wrote:My theory is that with the valves closed and a cooling engine it will draw some oil down. The pinned rings did help a lot but it certainly didn't solve the problem. Any bike that has horizontal cylinders will do it. The old oil head boxers did it and so do the Honda Goldwings from the left cylinder bank. When I was working for Honda we used to get a lot of complaints about the Goldwings.

I recently saw a fix to this problem.  The rider had a side stand on the right hand side... and one leg..he is from Toowoomba. Reggie is his name.

I have seen that one and had a yack (Talk) at Goombungee a few years ago.

Hej

Held og lykke med operationen, håber at du når turen til Harzen.

(just good luck an hope you are in time for your trip, in Danish)

It seem to be a bad season for the few Danish members inhere.

Cheers

Peter

Its alive!!!!! It startet after a few trys but with a sound almost similar to before 
took of the alternator and now it purs like a kitten ,im now waiting for the wife to bring back another  one . From Copenhagen .
pfew , cant wait for a test run on the freway 

k-rider

k-rider wrote:.still sounded ugly at low rpm but seemed to run fine above 3000rpm.
back home i pulled the thing apart and found out it was the starter sprag assembly 
grinding its way forward through the engine housing .
the bolt holding the drive dog for the alternator had somehow unscrewed it self  
and YES im a100% sure it was tourqed correctly.

Norwegian member Erman did have the same problem earlier this year.

https://www.k100-forum.com/t4208p200-the-slow-road-back-to-roadworthiness-a-blog#82718