ST1100 intermittent clutch problem

Hi there,
The problem I'm having with my 1999 ex-police ST1100 on 49000 miles is this:
With heavy use of the clutch in town traffic or slow maneuvering riding the clutch the clutch lever goes soft and no longer disengages the clutch.
Open road riding the clutch and gear changes are sweet.
Initially there was no loss of fluid visible anywhere.
The clutch came back to life after leaving the bike to sit and cool for half an hour.
The clutch fluid was changed and master cylinder internals replaced with a new kit.
The next time it happened fluid leaked from slave cylinder.
A new slave cylinder was fitted and Goodridge braided hose fitted.
This still hasn't fixed the problem.
Any ideas?
On one forum this is said:
"It sounds like clutch swell. That's when the clutch is abused and warping has expanded the clutch pack. As it heats up it expands even more. the net result is the travel of the clutch engadgement/disengadgement is greatly increased as the clutch pack is thicker when engadged. Therefore you have to move a lot more fluid before it reaches the point of disengadgement. This means a new clutch. Both metal and fiber discs. I would highly recomend rebuilding both cylinders and replacing the hoses with braided line. Do it right once and you'll never have to touch it again."
And on another this:
"So if you have serviced the master cylinder and the slave cylinder and replaced the fluid and the hydraulic hose to no avail, and you are happy with your work, then the problem must be at the clutch. I think it would need a new set of clutch plates, and would need the hole clutch (basket inner and outer and all parts connected) checking and measuring for wear. The clutch springs may now be very weak and effected by heat build up in the engine when in town or traffic. Also the clutch push rod and its bearing could be worn."
And finally this:
"Have you tried viagra in the clutch fluid?"
Ok seriously that last one I made up but any thoughts on this before I strip the clutch would be greatly appreciated as having a floppy clutch is never great when you've got a cute girl on the back of your bike.
Cheers

I have had the clutch fade in traffic. This was a problem when I used some synthetic oil.....I can't remember which it was of the top of my head. It shifted and ran great on open roads it was great......but it just did not hold up to the heat.

I would not rule out swell as stated but would start simple first. The clutch is not particularly hard to access or rebuild but it's down time.

There have been issues with clutches in the UK particularly on some ex-Policxe bikes where the slave cylinder needs overhauled and new fluid.... whilst your in there you might as well do the master cylinder seal kit too.....

Usually manifests itself when running stop go in town and getting very hot down there.....

Thanks for your replies.
I'm now in the process of replacing all the clutch parts including basket, springs, friction plates and steel plates.
The plates were very blue showing signs of severe overheating.
As some other posts have said if the clutch overheats and expands it causes the push rod to have to travel much further to try and disengage the clutch in the end resulting in a floppy clutch lever.
I hope this work will resolve this issue and will let you know.
Cheers

I'm having the exact same problem, drove 600miles no problems and in Plymouth the clutch faded and then stopped working altogether. After 10mins it was fine again. I changed the fluid thinking it was an old fluid problem and my clutch lever is almost completely out before it bites. It hasn't happened since but I will replace the clutch before I go on another long trip.

Mine is doing exactly the same although mine gas been stood for some time. So my first move will be to change both the master and slave cylinder seals.

Realised I hadn't posted any sort of update.
Well I got all new clutch system fitted by J. Tremlett in Ashburton and so far so good.
Haven't done any serious slow clutch work yet though as have only been out on weekly blasts during the winter months.

My clutch started acting up the same way today,began when i had the bike in the local St.Patricks day parade,had a run afterwards and I could be riding along at say 70-80 mph and the revs would shoot up to 7-8000 rpm,no increase in speed just the revs shooting up as if I had pulled the clutch,happened I suppose around 10 times in a 30 mile round trip.
I am no mechanic so I haven't a clue whats going on really but i suspect its clutch related.
The bike has been running rough for a while too,I ran two tanks with seafoam,changed the fuel filter to oem,bypassed the vacum valve also.power seems good but not just right,and then sometimes she just chokes from say 80 mph down to say 50 mph,very poor throttle response,then if she cools a bit or even if I just ride along at the 50 mph for a half mile or so she seems to clear herself and run fairly good again.
Any ideas anyone? thanks

Out of interest: how often do you guys replace the brake fluid in the clutch hydraulic?

broc that dont sound to good id say you have a fair problem with the clutch have you done an oil change recently?

Aye changed the oil a few hundred miles ago, motul 4T 10w40 semi synthetic,same as I used before,getting fed up with this bike,never had much luck with red vehicles looking back.
seems to be one thing after another.

Hi Guys. Just registered to chime in and say that I was having the same problems. My clutch worked perfectly until the engine temperature started getting hot. Then the clutch would just go soft and I could be left stranded without a clutch until the bike cooled down. Ex police bike with 96k miles on it.

Anyway I didn't have the bike long and knew the bike was due a timing belt so I had a go at the clutch slave cylinder while I was in there. Stripped the slave cylinder which was quite easy once you get the radiator off. I replaced the seals and all back together now it seems perfect hot or cold. I was in traffic today that would have been problematic before.

There is a small seal on the front, I replaced this, but it looks like it's the outer seal going that causes the problem. There was a few slight score marks on the rod which probably won't affect anything, anyway I put the rod in backwards so where it rubs the seal is now fresh. I took a few pictures on the phone while I did it.

I fitted a new clutch kit after that, it wasn't that dear and easy enough to do being that it's at the front of the engine as you know, where in Ireland are you located?

Hi Broc. In Dublin. Good to see some fellow paddies in here.

Youse guys in UK 'n the Emerald Isle do know ya gotta use brake fluid instead'a Guiness in the clutch system, right. int

LOL, yep I don't think she'd run too well on the black stuff George,I don't run too good on it myself either,at least not the day after!!

Had the same problem with a fading clutch when engine is hot and filtering in traffic,bled the clutch and it did improve the clutch feel,a little stiffer,though the fade did return, I stripped down the slave cylinder to look at seals, when I pulled the piston out there was water in the slave cylinder. Only a couple of xxx but enough to change the action off the clutch when it gets hot. Bleeding the clutch doesn't force any water out. Fluid comes in from the side and the nipple is on the top. It maybe worth just pulling the slave off and checking for any trapped water collecting in the bottom of the slave cylinder. Can only assume that it collects there over time due to the hydroscpic properties of the brake fluid

That is a good suggestion Gopher. I occasionally notice my clutch action "sticking" when the bike is hot, almost like the lever is jamming when I release it (but it is not). I have previously bled and re-bled the clutch and fully disassembled and cleaned the master and lever; it is better but not fixed, so I might pull the slave out for some love next.