Hi All

my clutch is driving me insane! Had the bike stripped, (06 rev3), with the engine out and the clutch hose disconnected at the slave cylinder. Since I've reassembled I can't get the clutch to generate any hydraulic pressure. Got new master cylinder seal kit installed, checked tightness on all connections, replaced banjo bolt washers and tried bleeding every way I can think of. Can't seem to get fluid to flow through freely on reverse bleeding. I think i'm getting air drawn in somewhere but have no sign of fluid leaking out. when I try to draw fluid through from the bottom with a syringe the bubbles go on forever. Thought the bleed screw was the problem but tried another spigot I had and still the same. Do the slave cylinders on these things fail and need replaced? Any suggestions as to where to go next much appreciated. 

 

Cheers.

Bleeding clutches is a lot more difficult than brakes, you can spend ages pushing air back and forward. If you un bolt the slave cylinder from the side of the engine it is much simpler, the piston goes full travel and bleeds just like a brake.  When bolting the cylinder back on It will just push the piston back as long as you haven’t taken too much slack out at the lever. If you can’t bleed it like that the you have another problem.

Hope it does the trick

Try taking mc lid off. Remove slave from motor and push piston in with your thumb. Then re try bleeding. 

If the slave has air in it the mc piston doesn’t create enough fluid movement to overcome the air space in the slave. Pushing the slave piston back in pushes any air into the narrower pipe and it can then be bled normally just by the mc piston doing the work. Doing this method has meant I have never had to try and back bleed clutches or brakes. It works every time. Worth a shot.  

Thanks for the suggestions. Gave it a go but still not managing to get any pressure. Is the slave cylinder serviceable? I'm assuming there's a piston seal and wondering if that could be goosed.

Have you confirmed that the master cylinder piston is clean and the fluid feed/return home isn't blocked? If it's clear then you should be able to back bleed with very little pressure. In fact, if you leave the master cylinder uncovered, the fluid will hit the garage ceiling... Ask me how I know. 

MC is clean and new seal kit installed. Going to try and replace the seals in the slave cylinder and then rebuild and try bleeding again.

20 hours ago, hoodie2 said:

MC is clean and new seal kit installed. Going to try and replace the seals in the slave cylinder and then rebuild and try bleeding again.

Do you know for sure that the oil oil is unblocked? I.e. have you blown air through it to check? Or can you see light through it? 

Clutch still won't bleed.

• stripped master cylinder ultrasonically cleaned it and then blew compressed air through. Checked fluid transfer with brake cleaner and confirmed all ports open.
• installed new MC seal kit.
• checked no blockage in hose.
• stripped slave cylinder and cleaned. seals looked okay so rebuilt with rubber grease. Pushed piston fully in and filled with fluid.
• rebuilt whole system with new banjo washers.

System will still not bleed from either direction and I have no hydraulic pressure. When reverse bleeding with a large syringe I just hit solid pressure and the fluid will not move through into the MC. Eventually I either get leakage through the bleed nipple or the pressure blows my connecting tube off the nipple.

Trying to bleed from the top I can only move fluid to about a cm from the nipple and no further.

Thinking to eliminate them I now need to replace the banjo bolt and bleed nipple and put a new seal kit in the slave cylinder.

Anything else I might be missing?

 

Leave the bleed nipple closed and loosen the hose at the m/c and pump to see if any fluid is moving.

PS, remove the lever and just use a phillips or round headed hex to pump.

Edited April 27, 20197 yr by lineaway

Just looked at a Grimeca clutch MC seal kit online. It had the usual boot for the plunger and the reservoir top seal plus another round seal. Where does that round seal go as I haven't come across one in my set up?

Cheers.

 Usually an o ring towards the other end. Look at other sets. Did you not have one on the old piston?

Had the hose off at the MC end. tried activating the plunger/piston with a screwdriver and initially got no fluid movement. After a few attempts I started to see fluid coming from the outlet. The only seals I have are the two on the MC piston. None on the hose to MC joint or inside the MC housing. Maybe I wasn't getting the full range of movement on the piston stroke.

 

 Exactly. That is why I suggested to remove the lever. It is easier to bleed using a long clear hose that will reach over the bars. Good luck.

The saga continues. The system has bled okay now but I still have not enough pressure to activate the clutch. The piston in the slave cylinder is moving when detached from the motor but doesn't seem to be activating when bolted on. I seem to have some fluid leaking past the new seals in the master cylinder so now wondering if the bore of the cast housing could be worn. Anyone come across this?

Clutch finally operational. The problem did turn out to be wear in the bore of the master cylinder. Replacing the seals wasn't enough. Replaced the MC and hydraulic pressure restored.