Flushing clutch fluid and can't remove all air,looking for advice...

mznyc

mznyc

Joined
Aug 10, 2008
Messages
11
Location
New York
Bike
1993 ST1100
Done many flushes over numerous bikes including the ST but was getting fade once warmed up(after a few hrs of riding) so since fluid was overdue decided to give her a flush and clean out he MC of crap so did let air in at that point but have never had a problem,cleaning out,refilling and pumping out .Had good pressure at bar before procedure but can't get it back.Tried manual method,pump lever,open, in to bottle with enough fluid not to suck back air and vacuum attached to slave,open then close.Still can't get all air out and pressure.Never let fluid get too low to suck in air....
What am I missing....?
 
Since air bubbles rise, you can pressurize the system (bungee cord or large rubber band around the handlebar pulling the clutch lever in) while you loosen the banjo bolt at the master cylinder. This also works well with a helper. Whacking on the clutch hose - well, tapping judiciously with a wooden dowel or stick can also dislodge bubbles. I asked if anyone had used one of those massage vibrators for this and got a couple of 'yes' responses. The vibrator did not work.

Back to the beginning. What did the fluid you pulled out look like? If it was really dark with bits of stringy glop you might have to rebuild the slave cylinder. For some reason a lot of owners neglect the clutch and the result is jellied goo in the slave cylinder.
 
SMSW said:
Since air bubbles rise, you can pressurize the system (bungee cord or large rubber band around the handlebar pulling the clutch lever in) while you loosen the banjo bolt at the master cylinder. This also works well with a helper. Whacking on the clutch hose - well, tapping judiciously with a wooden dowel or stick can also dislodge bubbles. I asked if anyone had used one of those massage vibrators for this and got a couple of 'yes' responses. The vibrator did not work.

Back to the beginning. What did the fluid you pulled out look like? If it was really dark with bits of stringy glop you might have to rebuild the slave cylinder. For some reason a lot of owners neglect the clutch and the result is jellied goo in the slave cylinder.
Click to expand...
Essentially that's what I'm doing,pumping a 100x ,hold lever and open banjo, but may be worth securing it overnight and letting any air travel down the hose.Fluid didn't look that bad,ordered a MC rebuild kit,but in theory,if I had good pressure at lever before I should be able to replicate as nothing but fresh fluid has changed...Shoulda just syringed out the little bit of muck that was in there and kept the fluid up but have never had an issue before restoring pressure...
 
I bought the Motion Pro brake bleeder. Its' basically 2 bits of hose and a one way check valve.

Put hose on nipple, into check valve, into hose, into a container. Crack open the bleeder valve, and pump away, making sure there's always fluid in the reservoir. When you see no more bubbles in the lower hose, close the bleeder and give it a try. Repeat as required.

If it's just stubborn air, pumping is your friend (and your nemesis....)
 
mznyc said:
They don't list them for the ST anymore on the site but put in a email over the weekend to them,so should know by tomorrow.I have one on my Guzzi because the slave is hard to get to and works great!
Click to expand...
Look at the chart.... the SB125LL is listed for the clutch...---oops, ST1300..
I see the ST1100 isnt listed. I think what I would do is order one each of the SB125L and the SB125LL. If you look at all the Hondas, one of those should work.
(Mbe grab some for the brakes too.)
.... btw, I like the SB125L far better than the SB125...they are the same except the "L" has a slightly longer bleed nipple, easier to hold a hose on it when working on it.
....... Also, I like to use a mini spring clamp on the bleed hose to keep it in place.
1759710423342.png


--Edit- part 2.... did some digging and looks like the Clutch Slave is common with the VFR750... so going by the chart the listing shows the the SB125, but I would get the SB125L.
*(my bucks are on that..:))
 
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mznyc said:
Essentially that's what I'm doing,pumping a 100x ,hold lever and open banjo, but may be worth securing it overnight and letting any air travel down the hose.Fluid didn't look that bad,ordered a MC rebuild kit,but in theory,if I had good pressure at lever before I should be able to replicate as nothing but fresh fluid has changed...Shoulda just syringed out the little bit of muck that was in there and kept the fluid up but have never had an issue before restoring pressure...
Click to expand...
What? There's muck in your clutch MC? Drain it! Clean it!
 
Regarding bleeding clutch, I had the same issue, as mentioned, ensuring the reservoir is always topped up, crack open master cylinder banjo 1/4 turn and pump four or five times then tighten and see if that works, did the trick for me. If you haven’t already, I take the plastic handle bar covers off to ensure no hydraulic fluid leaks down.
 
mznyc said:
Tried manual method,pump lever,open, in to bottle with enough fluid not to suck back air and vacuum attached to slave,open then close.
What am I missing....?
Click to expand...
out of interest:
a) do you apply full strokes or just tiny strokes on the lever?
b) is the tiny vent/reflow bore in the MC clear?

I normally do this job with my air-powered vacuum bleeder attached to the SC, never an issue, especially as I do this annually, hence no chances of any crud to build up inside...
The one time I had to do it by hand (an SC failed in a sub-level garage and dumped the brake fluid on the ground there, so I had to rebuild it right there) I found that full strokes at the MC don't work, whilst repeated little strokes constantly drove tiny bubbles (like the CO² in Champaign) out that small bore mentioned.
So after working that MC for >20 minutes (sore hands after that ;) ) the system was finally clear of any (micro) bubbles, providing proper function...
And if that small bore (its like a pinhole in a piece of paper) inside the MC is clogged in any way, it'll never work successfully... -> time to clean & rebuild
 
I just encountered this same issue. I purchased a vacuum bleeder from Harbor Freight. Hooked up to the bleeder, created some vacuum and pulled all the dirty looking fluid out. Added more fluid to the MC and second bleed got all the air bubbles out. Then had great pressure. Topped off the MC and all is good.
 
I just changed my first ST1300 Slave cyl.

I first used a syringe to remove all the nasty fluid in the master and used paper towels to clean the residue out of it.

Then I got slave off the rear cover.(First I removed-Shifter-Hose holder-Oil Filter-Speed sensor.)
Then loosened the Banjo bolt and washers.

Cleaned the gasket off the cover.

After adding brake fluid to the new slave.

I reversed the procedure.(loosening the Bleeder tube eyelet bolt-Allowed some metal tube movement getting the banjo bolt through the Master hose & metal bleeder tube.) a dab of grease on the washers helped keep them in place while getting the banjo bolt through the sandwich,into the slave.


Make sure to start the threads into the slave (with just your fingers) "Without" using a ratchet wrench
To finish installing the bolt, Because it's not hard go strip the aluminum threads in the slave,if the bolt doesn't thread in easily (if you do strip the threds?-You'll buy another Slave and start over.)

Bleeding the fluid was straight forward.

Add fresh fluid in the master, and open the bleeder. Then let gravity take over. (with one of the clear hoses attached on the bleeder nipple.)

I made a catch container W/two hoses going in just like the little cup most vacuum pumps come with.(it holds more fluid.)
I can flush out most of the brake caliper & slave bleeder valves without needing the Pump attached to the other hose in my catch container.

Pump the lever a few times, While keeping lever pressure to the grip.
I open the bleeder valve, and watch the fluid going into the catch container. I close the valve, and repeat the process.
I usually pressure bleed four full master bowls of fluid (to make sure I cleaned out the Master And Bleeder tube lines with fresh fluid.

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ST1100Y said:
out of interest:
a) do you apply full strokes or just tiny strokes on the lever?
b) is the tiny vent/reflow bore in the MC clear?

I normally do this job with my air-powered vacuum bleeder attached to the SC, never an issue, especially as I do this annually, hence no chances of any crud to build up inside...
The one time I had to do it by hand (an SC failed in a sub-level garage and dumped the brake fluid on the ground there, so I had to rebuild it right there) I found that full strokes at the MC don't work, whilst repeated little strokes constantly drove tiny bubbles (like the CO² in Champaign) out that small bore mentioned.
So after working that MC for >20 minutes (sore hands after that ;) ) the system was finally clear of any (micro) bubbles, providing proper function...
And if that small bore (its like a pinhole in a piece of paper) inside the MC is clogged in any way, it'll never work successfully... -> time to clean & rebuild
Click to expand...
Ya,I usually use a full stroke.I'll try the small increments method...
 
GTW said:
Regarding bleeding clutch, I had the same issue, as mentioned, ensuring the reservoir is always topped up, crack open master cylinder banjo 1/4 turn and pump four or five times then tighten and see if that works, did the trick for me. If you haven’t already, I take the plastic handle bar covers off to ensure no hydraulic fluid leaks down.
Click to expand...
yep,done it many times that way with no issue....until now....
 
Davez03ST said:
I just encountered this same issue. I purchased a vacuum bleeder from Harbor Freight. Hooked up to the bleeder, created some vacuum and pulled all the dirty looking fluid out. Added more fluid to the MC and second bleed got all the air bubbles out. Then had great pressure. Topped off the MC and all is good.
Click to expand...
Yup,tried both methods.Pump and manual.Still air in the line.
 
mello dude said:
Look at the chart.... the SB125LL is listed for the clutch...---oops, ST1300..
I see the ST1100 isnt listed. I think what I would do is order one each of the SB125L and the SB125LL. If you look at all the Hondas, one of those should work.
(Mbe grab some for the brakes too.)
.... btw, I like the SB125L far better than the SB125...they are the same except the "L" has a slightly longer bleed nipple, easier to hold a hose on it when working on it.
....... Also, I like to use a mini spring clamp on the bleed hose to keep it in place.
1759710423342.png


--Edit- part 2.... did some digging and looks like the Clutch Slave is common with the VFR750... so going by the chart the listing shows the the SB125, but I would get the SB125L.
*(my bucks are on that..:))
Click to expand...
I heard back from them,it's the SB8125L
 
May have found the issue.While re-assembling the MC,the Clymer manual requires that you remove the protector (#9 in the diagram) in the bottom of the cylinder and re-install when done,it was missing.I must have picked it up while wiping the reservoir out and threw it out with the paper towel.Seems like it would affect pressure as it has a smaller orifice than the feed under it....New one on order...



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mznyc said:
May have found the issue.While re-assembling the MC,the Clymer manual requires that you remove the protector (#9 in the diagram) in the bottom of the cylinder and re-install when done,it was missing.I must have picked it up while wiping the reservoir out and threw it out with the paper towel.Seems like it would affect pressure as it has a smaller orifice than the feed under it....New one on order...



Attachments​

Click to expand...
The #9 is only there to stop fluid from coming out of the master and getting all over the tupperware. (Think-water bubbler fountain)

It has nothing to do with pressure in the master cyl.

But it should Always be there (Just in case) :thumbsup:
 
Resolved.Don't know what fixed it but I ,
Put a bit more sealant on the SpeedBleeder valve.
Did a bench bleed of the MC on the bike and had good pressure on the output hole so knew the MC was putting good pressure in to the system.
When I removed banjo bolt I noticed the inner sealing washer was missing.Was pretty sure it was there when I originally assembled so may have fallen when taking apart.Had another on hand,installed it.
DOT 4 was new unused but been on the shelf for years so used a newly bought bottle.
All back together and within a min or 2 had pressure back.Test rode and all good!
 
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