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86 XJ700S brake bleed

Discussion in 'XJ Technical Chat' started by 78dave, Feb 1, 2018.

  1. 78dave

    78dave New Member

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    Columbia, MO
    I know this has been hashed about, but I am hoping no stupid questions applies here.

    I rebuilt the calipers, master cylinder and new brake lines. The bleeding process I know is lengthy from the handle and not the reverse bleed method. I am getting the lever to firm up. I find that I build pressure with some short strokes of the lever. Long full strokes seems to cause the small relief hole to spit brake fluid up. Is that normal? Second as I pump pressure builds and while holding the lever tight I release some fluid. Still getting some air I think. Once I tighten back the bleeder screw I let off the lever and it is still soft and returns to the handle with no resistance. If I pump it up will that pressure stay? Do you have to pump it back up as a final step or should it stay firm quickly without pumping it up?

    Sorry for all the questions, but I am pretty sure I installed the MC parts correctly (not that difficult) and I "zestfully" cleaned the calipers after splitting them. They were indeed full of junk. So am I going in the right direction? Do I need to inject some fluid into the bleeder and reverse bleed some?

    Thanks as always for your help
  2. cgutz

    cgutz Well-Known Member

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    SE South Dakota
    Sorry I can't help on the bleeding from the brake lever. I used a large syringe to force fluid from the bleeder valve at the bottom. Took about 10 minutes and no air in the line. Cover the open master cylinder, and cover the bike with plastic, as fluid will squirt up and over everything around. As you know, brake fluid destroys paint.

    I also had a bit of continuing "scrunchiness" on the brake lever. That's the best word to describe it - it felt like the calipers were sticking. Thought it was the calipers, took them apart several times. Almost ordered a refurbished caliper. Finally shot a little cable lubricant around the little piston under the brake lever that goes into the master cylinder. "Scruchiness" gone. I think residual brake fluid that had overflowed down there was causing some friction/stickeness.

    Working on these bikes is fun, because sometimes what you think is the problem, really isn't the problem. It can also be frustrating as a result.

    Enjoy, hope you get it operating safely.
  3. tabaka45

    tabaka45 Well-Known Member

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    Brunswick, Georgia
    Since you already have fluid in the system try k-moe’s method of using a hand help orbital sander (without sandpaper of course) starting at the calipers and working your way up the lines. It helps the small bubbles move up an into the m/c. If that fells try the syringe method. If you don’t want to remove the fluid the empty the m/c, go slow and empty the m/c before it overflows. Even better, have a friend with a second syringe to suck fluid out of the m/c as needed. I have an 85 XJ700N and it took me about 15 minutes using a syringe.

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