Clutch trouble which may not have been addressed on the forum earlier?

[Tom Nolan]

Hi all,

I have to describe my procedures in length since I don't have the vocabulary to tell it efficiently. Sorry about all the text.

My FJ1100 has been on the centre stand for almost a month due to some running problems. Two weeks ago or so I noticed the clutch lever had gone soft while the bike has been parked. I've not noticed any leakages, but I've spilled some other liquids from time to time and the fluid from the clutch may have mixed with other things and gone unnoticed when I've cleaned up. As I understand it, a leak from the bleeding valve area down on the left side is common, is that right? The black paint on the surfaces down there has flaked before I got the FJ, so I guess so. I think the former owner mentioned replacing some parts related to the clutch-fluid-system, but I'm not sure.

Anyway, I have experience bleeding brakes from other bikes and so I think I know the basics of bleeding a FJ clutch too, which I did this evening.

I was going to bleed the clutch upwards, i.e., use a syringe to push fluid into the valve down on the left side since air more easily travels upwards through the hose, and extract surplus fluid from the container by the clutch lever, where one usually fills the fluid. Anyway, I didn't have anything to extract the fluid efficiently with, and so I went with the downwards bleeding procedure:

I opened the container by the lever, saw what was definitely a fluid shortage, used paper to wipe out the rest of it and cleaned the container. Filled the container with new fluid. Connected a hose to the bleeding valve down on the left side of the bike, pull clutch lever, open bleeding valve, fluid flows out of the valve through the hose. Close valve, release the lever, pull and repeat, and refill container from time to time.

While bleeding there was a lot of air, not just bubbles, but continuous 'parts' of air, some centimetres/ many inches. I got rid of those enormous amounts of air after a while, I believe. Then I closed the bleeding valve and repeatedly pulled the clutch lever and filled the container to the max. of fluid. The clutch lever got harder and everything felt as it should.

But while pulling the lever, tiny air bubbles began floating to the surface in the container, and I heard a "suction" sound from the area where the lever pushes into the container. I haven't seen anything on this phenomenon on the forum. Is there a leak there sucking air into the container? Or is the problem leftover air in the system that I didn't bleed out, so I rather should have bled upwards instead of typically downwards?

Here's a video of the tiny air bubbles, and you can hear the suction sound. The suction sound is not the "friction" sound that's loud and clear when pulling the lever, but a more subtle, whistling sound when releasing the lever:

https://vimeo.com/840605550

All the best

[FJmonkey]

The small bubbles are likely the small amount of air still working up through the fluid. Small bubbles will rise till it reaches the master piston. When the piston moves, it allows the bubble to into the piston bore. When piston returns, the bubble escapes up into the reservoir.

[Tom Nolan]

The small bubbles are likely the small amount of air still working up through the fluid. Small bubbles will rise till it reaches the master piston. When the piston moves, it allows the bubble to into the piston bore. When piston returns, the bubble escapes up into the reservoir.

Aight, thanks!

Should I be worried about the suction/airy sound though?

And since the fluid has disappeared there must be a fluid leak somewhere. I've put some paper below the bleeding valve area, will look at it tomorrow, eventually the coming days, to see if that's where the leak is. If that's where it is, I've read that there's some o-rings/ seals etc. that must be changed, but that it's still a chronic problem. Hasn't anyone come up with a permanent fix as far as we know?

[FJmonkey]

Does the lever feel proper? Does it release the clutch plates and allow gear changes? Fluid disappeared?

[red]

Tom,

It's difficult to chase air bubbles down a vertical hose, because air bubbles rise while you work.  One trick is to tie the clutch lever fully back to the handlebar grip overnight, which allows that air to vent into the reservoir.  Refill the reservoir in the morning.  Repeat as necessary; it may take several days to let all the air escape this way.

You can also replace the banjo bolts at the clutch reservoir with bleeder banjo bolts, so you can bleed air from the hose as you would bleed the brake or clutch cylinders.  Always use new hydraulic washers, when you remove a banjo bolt.  RPMracing here sells banjo bleeder bolts for the FJ.
https://www.rpmracingca.com/proddetail.asp?prod=BanjoBoltBleeder

A vacuum bleeder pump is the cat's meow for bleeding hydraulic systems.  The cost is not excessive (~US$ 40 or so), but I have never used one.

If the fluid loss is constant, then you probably have a leak somewhere.  Usually the fluid "losses" are temporary, until all of the air is gone from the system.  Check for leaks at the clutch slave cylinder with paper towels for the next week.

[Sparky84]

Need to tickle the little bubbles out first

https://youtu.be/Vh9vpVejl1E