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Hydraulic Issue - Clutch Slip

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  • Hydraulic Issue - Clutch Slip

    Hi All,

    Recently bought a 2001 ZZR1100, and really pleased with the bike, particularly having had the ZZR600 and GPz900R in the past. Have got a weird clutch slip / hydraulic issue though.

    Start riding the bike when it's first started, and clutch works fine, no slip at all. ride it for 20mins so it's fully warm through, and it starts to slip as it hits the power at 6000rpm+. The more you ride it, the slip gets worse and worse. Lever gets more and more solid while this happens. Stop, crack open slave cylinder bleed nipple and fluid shoots out. Clutch lever back to normal (10mm of free play before it starts to move the plates), So the system appears to be pressurising and acting against the clutch springs, making it slip.

    Next day, it starts out fine when cold and repeats

    If I don't let off the pressure at the slave cylinder it's still solid at the lever a week later, so it's holding the pressure somehow, plus jacking up progressively, and the fluid doesn't seem to be able to return.

    Had Master cylinder apart, cleaned all the passages, new seals, removed some crud (thought this was the issue), new fluid, bled. No change though.

    Any suggestions? Has me baffled currently. Bike has 82,000kms on the clock

    Cheers
    Last edited by Thylacine; 08-13-2021, 10:08 PM.

  • #2
    Could be a few things. Make sure you have the correct fluid, DOT4 and it's a good brand name, not the cheap stuff.
    Make sure the lever is free and not binding. One thing else that comes to mind is, put a new kit in instead of cleaning
    the old stuff, sometimes what you clean it with can damage o-rings and make them swell when getting warm. I've seen a
    weak return spring do this when warm as well. Be picky as hell bleeding it too, I had to do mine several times when converting
    over to stainless line just to get it back to correct feel.Fluid is inexpensive too. Hope this helps.
    "If it ain't broke, don't fix it...
    but sometimes it just needs a mod"

    Comment


    • #3
      You might be due for a new set of clutch plates.
      I had my patience tested. I'm negative.

      Comment


      • #4
        Originally posted by BillDownUnder View Post
        You might be due for a new set of clutch plates.
        I agree with that assessment too
        "If it ain't broke, don't fix it...
        but sometimes it just needs a mod"

        Comment


        • #5
          Hi All,

          Think I might have found the issue. Had master cylinder apart again, and realised the small transfer hole was completely blocked with crystallized crud. Borrowed a 0.5mm dill from a mate and gently unblocked it. Much more movement at the lever now before it disengages, so pretty confident this was the issue. Shall find out next weekend with a long run…
          You do not have permission to view this gallery.
          This gallery has 1 photos.

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          • #6
            The line should be cleaned and flushed with new fluid added to remove any crystalized or hydrolyzed fluid. There are probably more crystals built up in other parts of the system. IMHO

            Comment


            • #7
              The clutch fluid in my ZZR1200 was not in good shape when I bought the bike at about 25,000 miles. A fluid flush and change improved the clutch feel, and I changed the fluid regularly after that.

              Sent from my SM-G980F using Tapatalk


              Last edited by Moise; 08-18-2021, 07:06 PM.
              "You don't get slower with age, you just get more cautious." Michael Rutter

              06 Ocean Blue ZZR1200, the coolest colour.
              99 Yamaha R1

              Comment


              • #8
                Originally posted by Thylacine View Post
                Hi All,

                Think I might have found the issue. Had master cylinder apart again, and realised the small transfer hole was completely blocked with crystallized crud. Borrowed a 0.5mm dill from a mate and gently unblocked it. Much more movement at the lever now before it disengages, so pretty confident this was the issue. Shall find out next weekend with a long run…
                Also, what kind of shape is the line itself? If it's still the original, change it. If it's a good quality aftermarket one
                remove it, clean the hell out of it, after putting it back on, flush system, ride for a while, flush it again.
                If this doesn't work, the clutch itself is bad.
                "If it ain't broke, don't fix it...
                but sometimes it just needs a mod"

                Comment


                • #9
                  The lines themselves sometimes can close up on the inside not allowing fluid to pass properly. You might want to replace the line too.

                  Comment


                  • #10
                    I had just the opposite happen on my 2011 Concours. The clutch lever would go soft and fail to disengage the clutch. A thorough bleeding and all was well.

                    Glad you figured it out.

                    Comment


                    • #11
                      Hope that was it
                      I have neither the time,or the inclination, to explain myself to a man, who rises and sleep under the blanket of the very freedom that I provide, and then questions the manner, in which I provide it. I'd rather you just say 'thank you' and go on your way.

                      Comment


                      • #12
                        Hi All,

                        Thanks for all the comments. I’ve never seen anything like this before myself. Airline wouldn't touch it - ended up trialling various diameters of wire between 0.5 - 0.6mm dia. before I could break through it. I suspect the fluid was very very old, possibly even original! Will be having the rest of the system apart to check there’s none of that crud elsewhere, Will also be giving the brakes a once-over. Still, we’re in lockdown again, so plenty of spare time to tinker on the bike…

                        Cheers
                        Last edited by Thylacine; 08-21-2021, 04:18 PM.

                        Comment


                        • #13
                          Originally posted by Thylacine View Post

                          Still, we’re in lockdown again, so …
                          So where are you located?

                          I had my patience tested. I'm negative.

                          Comment


                          • #14
                            You should disassemble the slave cylinder and give it a thorough cleaning. I don't think I'd use any rubber component, i.e. hose, again, replace what you can, clean everything. You're on the right track, you're fixing the system and that will be something you won't have to touch again. Hydraulic fluid absorbs moisture and produces that sludge. This is why I say replace any rubber lines as they are probably porous. I am suspect of the rubber portion of the line coming off of the reservoir. They have complete used systems on EBAY for around $69 bucks, only the lever isn't included. In a worse case scenario. IMHO.

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