Heavy gearbox \"clunk\"

Hi,

My old 1981 Z1000 J has been making some heavy "clunking" sounds when it is declutched at low speeds so as to avoid a stall and when clutching again to resume progess. its quite a deep clunk,

I have managed to emulate this by running the bike in low gear on the mainstand. Firstly when declutched but in low gear there seems to be significant friction such that application of the rear brake or a very heavy grip with hands is required to stop rear wheel rotation. I assumed that this was just normal friction in the wet clutch. Rolling the throttle on and off slightly with it in low gear whilct clutching and declutching seems to provoke the same heavy "cluncking" noise.

Could it be as simple as just rear chain tension or something more sinister? I have eyeballed the rear chain and that looks fine and earlier I had a lot of problems with the declutching lever over rotating and jamming declutched until I discovered the the Clymer manual only dealt with the worm adjuster and that my ball and ramp system adjustment mechanism was done 100% the reverse!

Bike runs fine under load and clutch seems to operate correctly under normal road conditions. Anything to worry about?

Try to locate the clunk.When the rear drive
cushions wear out the sprocket will clunk.
A loose counter shaft sprocket will make noise.
A loose clutch hub will make noise.So will a
loose stator.With the engine off,on the center
stand,in low gear,rock the rear tire back and
forth to create and locate the noise.Good luck,
keep us updated.

Would assure chain is not kinked and is lubed and adjusted for proper slack. And also check alignment of rear wheel.

Thanks Guys!

Pretty sure this noise comes from the lower engine area rather than rear hub. Given the earlier clutch problems I experienced I think it might be worth whipping the cover off and having a look.

How much drama is there in having a look at the clutch. All pretty straight forward unless you need to remove clutch hub where special tool necessary?

Clutch removal on the 1981 is not too
bad.