Rebuilt master cylinder & now no forward motion?

Sounds like air bubble lock in master cylinder.
 
jfheath said:
Notice what happens when the site of the bubble is tapped hard.
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From your video, John, the take away is that we should bleed brakes and clutches while pressing one of those vibrating/massage gadgets to the brake line. This is not a suggestion made in jest - years ago I had a very difficult time getting all the air out of new SS braided brake lines on a Guzzi. I solved the problem with a vacuum bleeder and a few quarts of brake fluid over several days.
 
Thanks for all the great tips and I'm on it but mostly thanks for giving me renewed vigor!

This will not:
Cause me to bow down to the frustrations this inanimate object is making me feel!
Cause me to believe this ST will break my will to fix it!
Cause me to act like a crazed maniac in front of my wife (any more)!
Cause me to believe I'm an idiot who cannot fix such a simple problem!
Cause me to grovel and plead that it just magically fixes itself (any more)!
Etc, etc...
 
Success! It took some tries of tips and right before moving into the fetal position crying for my momma... I did a reverse bleed from the bottom (using a tight enough hose that wouldn't "pop OFF" spewing brake fluid around) with the top disconnected from the master. Then made sure the master reservoir was full closed it up and primed it and carefully connecting the top of the line into the master cylinder (sorry didn't have new crush washer) without loosing much fluid. Still nothing - then I did a reverse bleed again with everything connected and the master cover off and the lever got good resistance and is staying. Oh what a relief it is, almost as good as _____________!

I'll ride if for some miles making sure it's good before putting it back on the market, boy it runs smooth (do the ST1300's run like these). Oh, anyone have any engine bar covers for sale?

I am VERY grateful for all the help, what a great community of riders this bike has introduced me to. Thank you! Michael
 
Okay, sooo sorry for not closing this thread. It’s finally fixed! Somehow I’d gotten the wrong plunger as well as air in the line??? So shortened the plunger by about 1/8“ish :) and finally got all the air out by holding my tongue just right, shaking my foot and playing country music backwards! I’ve never had soooo much trouble bleeding a system but now it’s over and clutchin smoooooth. Thanks to everyone for ALL the help.
:thumb: :usflag1:
 
Reverse bleeding usually does it for me too.

And sometimes just letting the bike sit overnight helps. Any air caught in the "caliper / piston " end tends to rises to the MC, given some time. I've noticed that on several occasions.
 
TerryS said:
My guess is that you have a blockage in the compensation port in the floor of the master. You will find a small pressed steel deflector in there, pick that out and you will be looking at a pin-hole sized port. When you release the clutch lever, any residual pressure bleeds out through this hole, and if it blocks you can build up more and more fluid pressure which stops the clutch lifter from releasing, so you get slip.

Best bet would be to disassemble the master and give it a good clean, especially making sure these ports are spotless.
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Hi there from Darwin in Australia. Just wanted to thank you very much for the information regarding the blocked compensation report in the clutch master cylinder. Here I was thinking I needed to replace my clutch plates and I found your post and it was a quick fix. My 2003 ST would be quite ok for 10km or so and then would lose drive in all gears. Once again Thanks...Dave.
 
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