CLatter, clatter, when does it go Bang?

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A friend of mine:
1) yes, I have a friend
2) it's not a euphamism, it really is his bike

has a 1200 GS that clatters like Carmen Miranda.
1) it's been doing it for 7k miles and no oil leaks
2) on the stand, in neutral, spin back wheel, silent and smooth. ergo not final drive. (?)
3) Engine running, first gear, big clatter from, low down and abaft the engine room.
4) engine off, first gear, rock back wheel, big clunking from front end of drive shaft area.

suggestions please.
I think there must be a CV/UJ at front end of drive shaft and I think this has given up. is there a write-up for checking/replacing? how long, how hard, how much?

The bike has done about 20k.
My friend has done much more, but, he's had a hard life.

 

[APB]

When the bike is on its center stand the angle the uj drives through is at greatest and struggles. add a few more revs and a little bit of back brake it should disappear.

 

[Pukmeister]

Your mates bike is fine, mine does the same.

Plenty of backlash in the drive train by design, wait until he goes off road in 1st gear and hears/feels the bike crunching back and forth on part throttle.

 

[Mr K]

Don't run it, in gear on the centrestand.

As detailed above you'll hear all the slack in the drive train and a dry clutch sounding like a Dalek having a **** in a dustbin.

 

[mechcanico lee]

How does the bike sound on the road as appose to on the center stand, when the bikes on the c stand the driveshaft goes through a very steep angle and loads the uj joints up.
I tried it on mine and it clanks and clangs like a clanky clangy thing, mines a 58 plate 5000 miles

 

[GSband]

... I think there must be a CV/UJ at front end. ...

CV ? UJ ?

 

[Engineer]

first gear on centre stand, bit clanky eh?,

sounds normal to me as there is no load on the drive train so all the slack in the gearbox and drive shaft will definitely cause a clonky rattle - might also sound worse when the engine is cold, low tickover, imperfect throttle balance etc.

Oh you might also notice some clutch rattle - try pulling the clutch lever in and out when in neutral, you should be able to hear a change.

They all do that

 

[[email protected]]

ssorry, poor description

should have said, the bike has been rattling away for several thousand miles. only put it on the stand to identify where the noise was coming from. It must be very unnerving to ride around sounding like you're shedding nuts and bolts at every yard.

 

[st247]

Mine clatters like **** on start up, but does go away after a few second running - i've put it down to the cam chain adjuster taking a bit of time to get pressure up.

If he thinks it's on the drive shaft you could cut the cable tie on the front boot to have a look at the front u/j. You could also drop the final drive to check the back one. Have a look at 'jim von badens final drive oil change with pics' to see how to drop the back.

I can only remember one drive shaft going on here but it was a very catastrophic failure - posted in the beakchat.

 

[D6]

CV ? UJ ?

universal joint, the bendy bit