My k100rs does something that I think I should worry about...
When I realease the clutch a bit too quickly (which happens because the friction point on my other bike is at a different place), I get treated to a loud clunk as it engages.
It seems to be coming from the rear, but I can't be sure if it's in the transmission or the final drive.
It's always done it for as long as I had the bike (2 years), but I don't ride it that much so I never worried.
Now I'm starting to ride it more, and also starting to worry abotu what it could be.
Any ideas?
(also, the clutch engages very far out at the lever and my friction zone is paper thin; I adjusted the clutch as per the manual).

Sounds to me like maybe a spline or uni joint is on the way out, Not sure if you have done a spline lube recently but an inspection would be a good starting point.

SittingDuck wrote:(also, the clutch engages very far out at the lever and my friction zone is paper thin; I adjusted the clutch as per the manual).

And maybe time to check the clutch for wear, and take a spline lube on this end of the gearbox as well.

Inge K.

Can you get a mate to sit on the bike and replicate the sound/noise? That way, you can stand beside the bike to get a better idea where the sound is coming from. It's a start.

Use a screwdriver between your ear and gearbox/swingarm/final drive.

Inge K.

id go with the inspection of the drive shaft as well ....but there are a few possibilities else where .



would be good to narrow it down to exactly where the noise is comming from ...got my fingers crossed for ya .

I think I'll put it on the centrestand and listen for it with my stethoscope.
I'll post an update (probably on Sunday)

I put my mechanic's stethoscope to the bike while reproducing the noise on the centrestand (this gizmo is a very good tool to have in your box btw).

The noise is very easy to reproduce: just let off the clutch fast.

It is loudest exactly in the middle of the swingarm. Is that where the u-joint is?
You think mine's toast?
How will it fail? Will it lock up my rear wheel?

The universal joint is at the front end of the driveshaft near the back of the gear box and allows for, of course, movement at the swingarm pivot. Here's what yours looks like.

Of course it would be at the swingarm pivot; how silly of me...
Hmm; my noise is about halfway dow the length though; any chance that my u-joint is so loose (and whatever bearings that support the shaft (if any) are so worn that I hear it slap the side of the swingarm?

SittingDuck wrote:It is loudest exactly in the middle of the swingarm. Is that where the u-joint is?

Will it lock up my rear wheel?

The joint is close to the gearbox, but it strange how sound travel in hollow parts.

A friend of mine did have a broken joint some years ago, it did not lock the wheel.
Lucky for him it happened only 5 km from my place, and he did say that it was 5
slow km`s with a sound like draggin` the centerstand along the street.
(the inside of the swingarm did not look nice).

Inge K.

u joints invariably fail in the bearings ....they just dry out ....and as most are sealed in the assembly process there doesnt seem a way to re-pack them ...unless you have the foresight and tools to do it .



the needle bearings usually get to an overheat mode and the hardened casing outer of them peels from the metal, followed by soft steel becoming the bearing surface ...now i dont have to tell you that once that starts to happen the whole thing becomes a mush of crushed metal ,,,,fortunatly the whole thing is an interference fit so worst case you will hear realy loud clunking on each revolution and as the uj goes through an angle change .



but ....could you be hearing a sloppy spline to pinion fit happening or a worn out put bearing on the bevel box , the noise might just be more resonant at the cente of the swing arm . and you wouldnt neccesarrily hear it till you put a load on the whole deal .



the drive shaft proper has a rubber assembly that takes the rear half of the spline interface down its centre and an outer tube that suports it all the ujoint is then fitted to the outer jacket via a flange assembly .



one of the things i have noticed about the k drive shaft is that there is a circlip thingy that positions the drive shaft on the gearbox output shaft splines ....if the last service and lube didnt bash the drive shaft onto output shaft properly the clip may not have got to the retension releif and hold it in the correct position .angle for the whole thing to work secondly if it doesnt get punched up properly the drive shaft will bind , be hitting on the pinion nut as there is only a few millimeters of gap between the two

in fact when i replaced my shaft to a different bevel box ...i couldnt actually do the whole assembly up on the swingarm as the interferance was holding it out about 2 mm .......i ground about 5mm of shaft away ...and its been great for that last 4000ks

.

in any case its worth a pull apart and inspection ...

there are heaps of threads in here about spline lubing so use that as the dissassembly instructions .



but im thinking also might be worth a swingarm disassembly to see what the output shaft and bearings are doing if you dont find an imediate answer from the rear end .

Sometimes the doctor can simply perform a 'back passage exam' and easily find the problem with a bit of feeling around, but other times it's required to go a bit deeper and get a close up look at the pieces and parts to see if they're functioning as they should, and to correctly diagnose what is causing the noise. This is known as a Kolonoscopy.

yeah left myself wide open for that quick quip ....giggles

If the conclusion ends up with that it`s the joint that is the problem.
Did read somewhere the last few days about a guy that got the bearings
(and X) changed at a driveshaft shop.

Inge K.

shouldnt be too hard inge .....just a good press and lots of adaptors to fit the relativly small size caps .???

And some grinding tools (or similar) I`ll guess, since it ain`t got any circlips.
Another history is to get the correct part.

Inge K.

aye !!

Having investigated one not long ago getting it apart is very easy but putting it back together so that it aligns correctly is a very precice job and would need a high quality jig.



I believe that Munich Motorcycles in Perth Oz do a reco shaft so I would presume that others also do it. Would be a matter of finding them.