Engine knock.

R1100GS, 1994, 80K kms, properly serviced.
Symptoms: when the engine has reached normal temperature after a run, let it tick-over,(bike standing upright,not on sidestand), an unpleasantly loud knocking noise can be heard coming from the clutch area.
Slowly pull in the clutch lever,(still in neutral), and the noise diminishes as the lever is pulled,reducing to nothing when the clutch lever is almost fully in.
Bike rides 100%, nothing untoward can be heard or felt when moving.
The noise has slowly increased over the last 500kms.
My suspicion is wear has developed in the main bearings, but I am renowned for fearing the worst!
Has anyone else experienced the same?
I've done a search but not found anything exactly the same.
It serves me right for starting a positive thread about trouble-free ownership!

when you pull in the lever you are disengaging the gearbox and applying pressure to the clutch pressure plate,
firstly check the basics, like gearbox oil, if its okay then you it could be clutch chatter.
worse case is gearbox bearings,

I've just changed the gearbox oil as a precaution,it came out looking like new and the magnetic drain plug was clean enough to rule out bearing damage, (but not wear).
Can't feel any gearbox harshness when riding.

Might be worth removing the front pulley cover and seeing what happens to the front crank pulley when you operate the clutch lever. Any sign of in/out movement means worn crank thrust bearings.
If no movement it could possibly be worn clutch pressure plate springs causing the cover to knock/rattle.

Been right through everything possible this afternoon, the noise is definately coming from the front of the gearbox,clutch area.
All the transmission turns smoothly,all oils are correct and at the right levels.
Went for a 50km run without a problem,I'm beginning to think I've identified or singled out a noise I've not noticed before!
Normally when I arrive home,I turn off the engine,then remove my helmet,yesterday I removed my helmet before stopping the engine,perhaps this wasn't a shrewd move!
I'm convinced I've become more paranoid about the bike after reading the 1200 threads,I'm going to keep away from them :white

I think it is either:

A) Clutch friction plate rattle from damping springs: When you operate the clutch and remove drive, the noise stops.

B) Gearbox internal gear/shaft endfloat, increased a little over the 80K.

If it was engine related, I suspect it would continue to knock regardless of clutch position, hence I suspect either a clutch or gearbox problem.

I agree, however, I'm shying away from changing or inspecting the clutch at the moment.
This winter I'm planning on converting the bike to carbs,while everything's apart for removal of the to-be-surplus electrical and electronic gubbins would be the best time to remove the gearbox for inspection.
I bought and stripped an R1100RS for spares earlier this year and couldn't believe the amount of electrical harnessing,etc.
BMW must have had the harness designed in the car department,then spent a week or two finding a way to get it all onto a bike!