Clutch hyraulic question

[atye]

OK, I have a sticking clutch slave cylinder that will not fully release. If I bleed the line (which I have already flushed completely), it works fine for a couple of uses, but after each use it only returns about 90%, so, after a few uses, the clutch is engaged enough to start slipping. If I bleed it, the cycle starts all over again. Good clutch for a few pumps that slowly goes away.

My question is this: What would be the best way to determine the exact part that is failing? I have never liked to "shotgun" a repair and just replace parts blindly until it finally goes away. I like to understand the problem and how and why the part failed. I am a pretty good troubleshooter, but this one has me puzzled. How do I isolate the 3 major components (master...hose...slave) and test them individually? Is it even possible or maybe it's not in this situation? I'd hate to rebuild the M/C only to find out that the hose or slave is bad, you know?

Any ideas?
Thanks,
Alex

[Toxz Qwaste]

FWIW: I have had this type of symptom with car brakes in the past. Replaced the caliper-still the same. Replace the master-still the same. Replace what looks like a perfectly good flex line to the caliper-everything works good-on the road again.
 A profession wrench educated me long ago that the inside of the line could collapse and act like a check valve and give you these symptoms. I don't know the age of your machine or how many miles, but this is a possiblility. I haven't found a way to bench-test this failure. It's just replace and pray with this type of failure. Good luck
-Rich

[works4me]

I'll bet it's dirt clogging the return port in the master cylinder.
Take it apart , clean thoroughly, re-assemble, refill and
bleed.
If problem persists do the same to the slave cylinder.

[Leo]

I believe works4me called it right.  When that bleed hole clogs it does exactly the symptom you describe.  Since the clucth system is really low pressure it is easy to clog.  Clean the master cylinder.   Good Luck

[atye]

In my previous life, I worked for NAPA and saw a lot of brake caliper hose issues caused by exactly what you mentioned, Toxz Qwaste. That was the first thing that popped into my mind.

I do believe that I will do what works4me and others have suggested as the first step and carefully clean the master cylinder itself. It's easy enough and will either fix the issue or eliminate the master cylinder as the culprit.

Thanks for all of the replies, I will have more questions, I am sure!

[connie_rider]

I'll take a stab at it..... (Wild as__d calculated guess).   

From what your saying, you think some pressure is trapped in the master, hose, or slave which is preventing the clutch from moving.

To troubleshoot it, isolate the sections.

1. Operate the clutch until it reaches the point that it does not return. (90%)
2. Loosen the brake line at the slave cylinder.
    If the clutch extends, the blockage is in the master or hose.
    If the clutch reamains in the 90% position,. the slave has a problem.
3. (Repeat) Operate the clutch until it reaches the point that it does not return. (90%)
4. Loosen the brake line at the master cylinder.
    If the clutch extends, the blockage is in the master.
    If the clucth reamins in the 90% position, the hose has a problem.

In all cases, watch the fluid that comes out. At some point you will see increased flow due to the slight pressure being released.

Ride safe, Ted

[atye]

Now THAT is what I have been looking for, connie_rider!

A nice, easy to implement troubleshooting procedure. I was trying to wrap my brain around a way to do something similar to isolate the root cause of the problem.

I will try it tonight and post my results.
Thanks!

[connie_rider]

Hope it works.

Ride safe, Ted

[stevewfl]

This Concours forum rocks

[SteveJ.]

This Concours forum rocks

^

There are two holes in the bottom of the master cylinder bowl as you are looking down into it. The (very)small one is the one that tends to get plugged from not so good attention to maintenance. I'd be replacing every fluid on that bike, given the condition of the clutch system. I like my machines to be reliable.

Also strongly consider replacing all coolant hoses, if it's not been done in the last 4-5 years. Sitting on the side of the road waiting for a tow truck cuz a $4 hose breaks really would suck. Murphs' has a kit, reasonably priced compared to Ma Kaw. Plus, he's a decent dude.