Clutch Bleed

[Dukedesmo]

Clutches are harder to get the air out than brakes, presumably because the clutch moves all the way to end of the lever so you can't squeeze a 'solid' circuit to get the last air out.

Maybe you could somehow block the slave cylinder so that it's up against a stop to get the pressure on it?

[Saint aka ML]

I use a vaccum pump. Hand held.

You attach it at bleed nipple end by clutch/brake. Make sure master is full and lever fully pressed (or you pump it for quicker bleed).

Then I pump the vaccum pump few times to get negative pressure, pump brake or press clutch lever and at same time open the bleed nipple. Fluid goes out. Close quickly, refill master and repeat.

Tied it back overnight, bled at master, then slave. Started it up and it seemed better, but as it warmed up it seemed to deteriorate. Big clunk engaging gear, but not creeping forward or anything when in gear with clutch in. I'm tying it back again tonight, if that doesn't work I might just take into a dealer.

[Joshua Brew]

Hi, when using the vacum pump do you keep the leaver pulled in?

I haven't got a vacuum pump, so doing it the old fashioned way.

Thought I'd have a last go today, lever tied back all night, bled fro master, then slave, then master, as usual not a single bubble and good feel at the lever. Rocked it back and forth in gear to try and loosen the plates up. Started the bike up and went into 1st gear like butter. However, as before it started to get worse, not sure if it is as the bike warms up or as I sit there repeatedly putting it in 1st gear then neutral. After getting it up to 3 bars temp, and putting it in and out of gear several dozen times there is a very noticeable clunk, but not as bad as before. I think it would be perfectly rideable, no creeping forward with clutch in, easy to get into neutral. I think I'll leave it at that until the roads clear up and can try riding it.

Thanks for all the advice.

[Darren69]

Is it a dry clutch on your 1100s? If it is then you should be able to turn the pressure plate by hand with the clutch pulled in, with the engine not running obviously. Its an easy way to check if you've got enough lift to release all the spring pressure off the clutch. This can be a problem if you fit an oversize slave and the standard master as I did,its marginal but I don't get any clunks on mine but have to have the lever span adjusted out all the way.

[Dukedesmo]

Originally Posted by Darren69

Is it a dry clutch on your 1100s? If it is then you should be able to turn the pressure plate by hand with the clutch pulled in, with the engine not running obviously. Its an easy way to check if you've got enough lift to release all the spring pressure off the clutch.

My test is that not only can you turn it by hand but if you 'spin' it, it should rotate a little after you let it go. If not then it will likely drag, making neutral hard to select whilst stationary.

I find that a pack thickness of less than 38mm with no convex plates makes for the best clutch action.

[Darren69]

I'm not sure mine is that free but you can feel it moving freely if you rock it back and forth, there's still a bit of friction but it rattles when moved back and forth by hand. It might help with bleeding if you have the lever span set to max to get the most piston movement which will help get all the air out. I don't have the luxury of a master bleed on my old 916 style masters but find the banjo bleed (barley and grape rag) method works well as the air gets trapped at that high point in the system and piston movement alone isn't enough to shift it.

[Dukedesmo]

Originally Posted by Darren69

I don't have the luxury of a master bleed on my old 916 style masters

My Monster has an RCS clutch master with built in bleeder but my 916 still has the original clutch master cylinder but I fitted a new banjo bolt with built in bleed valve that does the job nicely, only cost a few quid.

I had another look with the clutch cover off and the engine running. I noticed that before it warmed up if I pulled in the clutch lever the clutch itself almost stopped spinning, as it warmed up it didn't slow down nearly as much when I pulled the clutch in. Clutch components are all standard, and this problem is all the result of a straight forward flush.

I wonder if it is worth pulling the slave cylinder and cleaning out the clutch rod, etc., presume I can do that without draining down the system?

Cheers

Also, out of curiosity, what is the point of the 2 screws without washers that fit through the enlarged holes on the clutch cover so aren't actually contributing to holding it on at all?

[Dukedesmo]

Originally Posted by TonyG

Also, out of curiosity, what is the point of the 2 screws without washers that fit through the enlarged holes on the clutch cover so aren't actually contributing to holding it on at all?

The long screws that pass through are actually holding the crankcase side cover on, along with the long clutch cover screws.

[Mr Gazza]

Originally Posted by Dukedesmo

Maybe you could somehow block the slave cylinder so that it's up against a stop to get the pressure on it?

Maybe a wedge under the cover to stop the pressure plate coming out?
Easy on a cutaway cover.

Originally Posted by TonyG

I noticed that before it warmed up if I pulled in the clutch lever the clutch itself almost stopped spinning, as it warmed up it didn't slow down nearly as much
I wonder if it is worth pulling the slave cylinder and cleaning out the clutch rod, etc., presume I can do that without draining down the system?

I doubt engine heat will effect the slave much, especially with new fluid. Old fluid might?

Engine heat is more likely to effect the clutch side, I would have thought.
Normally you would be riding through the air and getting rid of heat from the clutch, so your experiment is not exactly "real world" and I think a ride out will bear this out?
An open clutch cover will help the clutch run even cooler, it will tend to blow dust out too.

Your static warming test is more like a heavy traffic situation, where a bit of clutch drag can often manifest itself anyway.

I would have all the plates out and give them a good wash with clutch & brake cleaner.
Check the grooves in both drums for notching and wash those too, also check the friction plate tangs for burrs. They should be in pretty good order at that mileage.
Some people shuffle the plates when re-assembling, presumably to distribute wear, but obviously retain the order of the plate types if you do that, noting the position of the dished steel plate, if you have one.
Also note the position of the pressure plate, with the arrowed spring hole going over the post with the "screwdriver" like slot in it.

Most importantly though, don't lose too much sleep over this... A good ol' Italian tune up will probably sort it.

[jerry]

cheap vacuum pump is a large plastic surgical syringe 100-200 ml and some tube ...

I like the idea of maybe wedging the clutch, that should make bleeding more effective. I've only warmed it up to 2 to 3 bars which is normal operating temperature. I could strip the plates but it seems like I'm going over the top for something I seem to have cocked up by doing a simple flush.
You are right, I shouldn't get too irate as it seems to be rideable, but I'm a natural worrier.

Tried using a syringe as well, but no luck.

Cheers