Sunday, 25 April 2021

Kawasaki Concours C14 Pneumatic Clutch Bleeding

Following that helpful advice on the site below, I gave the clutch bleeding another go yesterday.  I should have assumed there were multiple bleed nipples on this very complex and over engineered motorbike.

That poster suggests using a powered bleeding tool instead of the handpump kind.  My handpump one has been heavily used over the past five years.  The glass on the gauge fell off and the rubber hoses have gotten brittle and don't connect well.  On top of that the pump has started locking up on me so I just happened to get an air-line vacuum bleeding tool only a few weeks ago and it's a revaluation.  If you do bleeding in your own garage and have an air compressor, this thing isn't very expensive, seems well built and holy cow does it bleed!

For about thirty bucks (CAD) this thing makes bleeding a much less fraught experience.  The rubber tubing it comes with is flexible and grippy and makes a secure connection with the bleed nipples.  The vacuum control (the red lever) produces even, strong suction that makes bleeding much easier.

Terrible pic, but I'm pointing at the lower bleed
nipple for the clutch down by the gear change.
Bleeding the complex clutch pneumatic system on the C14 is described at "quite difficult" and the hand pump made that the truth.  The air compressor powered bleeder made producing even, consistent pressure much easier, but I was still unable to get the clutch to firm up until I read that piece below and realized there is a second bleed nipple up by the reservoir on the handlebars.  The GTR1400 is a complex beast, but once you start to get your head around how they engineered it, it all starts to make Connie-sense.

Make sure you're keeping the reservoir topped up with DOT4 brake fluid and bleed the top nipple.  When you're getting consistent fluid out of that one do it all up tight and then do the bottom nipple down by the gear shift.  You have to remove fairing to get to the bottom one.  Strangely, the top nipple is 8mm and the bottom 10mm, so you'll need two wrenches to do the job.

Once you've got the bottom one producing bubble free fluid you can lock it up and the clutch comes back immediately, or at least it did for me.

With the clutch flushed and filled with new DOT4 synthetic, I'm looking for wiring diagrams for the windshield.  The mechanism seems to be in good shape but there is a relay click from somewhere near the ignition module when I press the windshield rising button, so I suspect a bad connection or something electrical is at fault, but I need a wiring diagram to hunt that down.

I was worried that the C14 would be too much of a technical handful to DIY, but it's a beautifully crafted thing engineered to within an inch of its life.  As long as you can get your head around that it's not a particularly overwhelming thing to work on, but then I haven't had to put it all back together yet (keep your fasteners for the complex body-work in order!).

Thanks to for this helpful advice:

"There are two bleeders; the first one is on the clutch master cylinder, pointing straight up.  The second one is on the slave cylinder which is on the left side of the engine. I believe on Gen. 2 C-14's you are going to have to remove the left fairing to get at that slave cylinder.

Bleed the top bleeder first and continue until the fluid is perfectly clear (no air bubbles or foam in the fluid). Then move onto the second bleeder and continue the same way.

Note that these bikes can be quite difficult to bleed at all, and also to finish bleeding (soft clutch or brakes that are nearly impossible to get the last of the air out of). I ended up buying an air- powered vacuum bleeder in 'self defense' just for this bike but they are expensive. The traditional way of pumping the system and then holding pressure on the lever while cracking the bleeder often just does not work as the system will not pump up in the first place."

When I finally took the bike out the clutch isn't disengaging drive properly and event though there is some feel at the lever it isn't enough to engage the clutch.  I've run an entire bottle of DOT4 through it and still can't get it clear.  Time for some alternative tricks:

"Ended up holding the mityvac hose right on top of the fluid hole over the piston and pumped the lever while sucking. Seem to clear the problem and got lever pressure back. must have got a particle of dirt in the mechanism."

Another option might be to gravity feed fluid into the bottom bleeder and then draw the fluid (and bubbles) up from the bottom and out of the reservoir.

Speed Bleeders for the C14:

Speed bleeder how to:  

Positive pressure bleeding is an alternative.  Perth County Moto has a hand pump:  I wonder if they have any more German police leathers...

Followup Followup:

Finally got the clutch sorted today.  I got a fluid pump with a one way valve in it and pressurized the lower bleed valve and then drew fluid (and bubbles) backwards (bubbles like to go up) out of the reservoir using the vacuum pump.  Lotsa bubble, then less and less, then none.

The initial fluid had a lot of debris in it (little black dots).  Once I got them out there was a little black tornado of very fine debris which I also vacuumed out.  I suspect this system has never been changed (the bike is 11 years old but low miles and minimally maintained).  With all the debris finally out and the fluid clear, more bubble came out (moving the steering side to side seemed to really do the trick).  When no more bubbles came out the clutch feel immediately returned.

I took the bike around the block - great clutch feel and engagement.  That clutch is a f#*@er to bleed!  Next winter the Connie gets a set of Murph's speed bleeders and I'm doing the brakes (which have also probably not been done any time recently).