2002 R1150R clutch issue

Bought this bike recently as a non runner and a bit of an unknown quantity. Replaced the throttle cables, switchgear and renewed all the filters, oils, brake and clutch fluids.
The bike now starts and runs beautifully and the clutch was smooth, light in operation and gear changes were seamless compared to my old Guzzi.
Just about to take it for an MOT test, and the clutch lever came straight back to the bar failing to disengage the clutch……
Now I know through riding her around the garden for half an hour that there’s nothing wrong with the friction plate and this must be either the master or a slave cylinder seal that’s gone soft and turning itself inside out.
My questions are how do you work out which cylinder is the one needing to be stripped out, and are repair kits available or even worth considering?

Of course the clutch is back to its normal operation now, but I can hardly rely on it remaining usable, or easily diagnose it until it goes bad again.

There is a repair kit available for the master cylinder, but not for the slave cylinder.

If your master cyclinder fluid is black with metal particles in it, then it’s most likely the slave cylinder, as the piston is spinning in the cylinder grinding away.

I’ve repaired the master cylinder with the repair kit, no problems.

Repair kit part No 32727665445.

The clutch fluid turns a silvery grey if the slave cylinder has failed. You can remove the slave cylinder from the back of the gearbox with the clutch line still attached fairly easily - helps if you undo top nut of L/H fork leg and move the clutch line the other side of it to give you enough slack to pull the slave out- it might visibly obvious once removed. If not then insert/push a suitable socket into the slave forcing the piston into the body, clamp it in place and pull the clutch lever, if the lever is solid it’s the slave cylinder, is the comes back to the bars it’s the master cylinder

Steptoe said:

The clutch fluid turns a silvery grey if the slave cylinder has failed. You can remove the slave cylinder from the back of the gearbox with the clutch line still attached fairly easily - helps if you undo top nut of L/H fork leg and move the clutch line the other side of it to give you enough slack to pull the slave out- it might visibly obvious once removed. If not then insert/push a suitable socket into the slave forcing the piston into the body, clamp it in place and pull the clutch lever, if the lever is solid it’s the slave cylinder, is the comes back to the bars it’s the master cylinder

Click to expand...

That’s a really handy tip! Thank you.

Ian J Hartley said:

There is a repair kit available for the master cylinder, but not for the slave cylinder.

If your master cyclinder fluid is black with metal particles in it, then it’s most likely the slave cylinder, as the piston is spinning in the cylinder grinding away.
I’ve repaired the master cylinder with the repair kit, no problems.

Repair kit part No 32727665445.

Click to expand...

Thanks for the input too. I’ll go and see if I can get it detatched without disconnecting the lines.

I’ve just had another look at the job. Looks a bit of a pain to remove the slave cylinder to test it by jamming the piston with a socket. Unfortunately, a previous owner had (sensibly) upgraded the rubber lines (feed and bleed) with Aeroquip type steel hoses, so I can’t just put a clamp on the line to test the master cylinder.
The previous owner paid quite a bit of money for someone to unsuccessfully sort this out, and the slave cylinder actually looks new, so I’m just wondering whether the master piston seals are being bypassed, and the fluid is being pushed back into the fluid reservoir rather than giving pressure down the line.
There’s no visible leakage of fluid either at the lever or at the slave, although I appreciate any leak at the slave is likely to be unseen within the bellhousing/clutch plate area.
When the bike was cold the clutch worked faultlessly, but once it got hot and after I balanced the fuel injection and took it for a run the lever suddenly came back to the bar which makes me suspect the slave which is more likely to be affected by the heat, but I think the best/easiest first effort will be to dismantle the master cylinder in the hope that the seals are noticeably soft, as the new Aeroquip type lines makes me suspect the slave was likely changed at the same time. It’s also an easier cure as the master is more easily accessed.
Bike has done 75,000 miles, and I was told (and believe) that the friction plate has been renewed recently.
Does my guesswork and plan sound reasonable? ��

Hi Godfrey, I'm based not too far away from you and I'm definitely no expert but I have had the gearbox out of my 1150GSA a couple of times to do clutch work and have replaced a couple of slave cylinders due to leaks so I could maybe have a look for you at some point if you need a little help.
I know that Steptoe removes the slave without removing the swingarm and you can do this with the right tools but it's easy enough to remove the swingarm ( and properly re-grease all the needle bearings etc ) and then the slave is easy access.

Something to try first, use some ball end Allen keys and slacken off the slave in situ, fiddly but doable..if brake fluid runs out then it's time to take things apart as the next contact point is your clutch plate