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Front fork air pressure not holding

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  • Front fork air pressure not holding

    After months of struggling with grooved inner tube leaking fork oil, the oil now seems to be staying in. Now the air. I used a handpump but it never seems to build pressure anywhere close to 5.7PSI(manual spec for Special). When I push down the center of the valves, no air comes out. That I guess suggests that it the caps are not holding any air at all. The pump works fine with bicycle tires. I already replaced the valve cores.

    Any suggestion on what to check next?
    dontlikeoc
    1981 XS1100 Special Edition
    Alhambra, CA

  • #2
    My guess would be bad, or the wrong, fork seals. The ones for air forks have a "double" lip seal that helps hold the air in. If your sure its not fork seals then....

    Do you have an air compressor with a regulator on it?

    If you do this is what I'd do, get one of those air chucks with the deal that allows it to hook onto a valve - so you can put it on and it holds itself there.

    1. Turn the regulator down on the compressor to like 10ish lbs.
    2. Get a spray bottle with soapy water.
    3. Hook the fancy air chuck on your fork valve and let the air run in.
    4. spray soapy water on places where air could be leaking out. When you see lots of bubbles forming there is your leak.

    Other wise I suppose you could have a friend pump with the bicycle pump while you look and listen for leaks....
    1979 xs1100 Special -
    Stock air box/K&N Filter, MAC 4-2 exhaust, Bad-Boy Air horn, TC fuse box, Windshield, Soft bags, Vetter Fairing, Blinkers->Run/Turn/Brake Lights, Headlight Modulator, hard wire GPS power

    Short Stack - 1981 xs1100 Standard - lowered for SWMBO.

    Originally posted by fredintoon
    Goes like a train, corners like a cow, shifts like a Russian tractor, drinks like a fish, you are gonna love it.
    My Bike:
    [link is broken]

    Comment


    • #3
      Thanks for your reply. The seals are correct. I checked the order sheet with PartsNMore.
      Well, I dont own an air tool...
      dontlikeoc
      1981 XS1100 Special Edition
      Alhambra, CA

      Comment


      • #4
        I'd offer to help you track it down, but it would be a long ride for a day trip for you to come to my place...

        What about one of those little battery jumper air compressor things? If the air is leaking out anyways you shouldn't be able to build to much pressure.
        1979 xs1100 Special -
        Stock air box/K&N Filter, MAC 4-2 exhaust, Bad-Boy Air horn, TC fuse box, Windshield, Soft bags, Vetter Fairing, Blinkers->Run/Turn/Brake Lights, Headlight Modulator, hard wire GPS power

        Short Stack - 1981 xs1100 Standard - lowered for SWMBO.

        Originally posted by fredintoon
        Goes like a train, corners like a cow, shifts like a Russian tractor, drinks like a fish, you are gonna love it.
        My Bike:
        [link is broken]

        Comment


        • #5
          I'm guessing that if the groove is still there, while you may not be leaking oil, you may not have a good enough seal to keep air in it.

          I would +1 on the soapy water, although it may take a friend pumping while you spray the soapy water around the seal area, I'm guessing you will get bubbles there, if not, spray everywhere to find where it's actually leaking from.

          You can seal oil in while not being able to seal air in, but if that's the case, the seal will probably not last long before it starts to leak again. I would suggest it's time to look for at least a replacement inner fork tube, if not the whole assembly.
          Cy

          1980 XS1100G (Brutus) w/81H Engine
          Duplicolor Mirage Paint Job (Purple/Green)
          Vetter Windjammer IV
          Vetter hard bags & Trunk
          OEM Luggage Rack
          Jardine Spaghetti 4-2 exhaust system
          Spade Fuse Box
          Turn Signal Auto Cancel Mod
          750 FD Mod
          TC Spin on Oil Filter Adapter (temp removed)
          XJ1100 Front Footpegs
          XJ1100 Shocks

          I was always taught to respect my elders, but it keeps getting harder to find one.

          Comment


          • #6
            on your other thread you said you had a shop do the seals, then re-do them again.

            Are you sure the shop used the right seals? Did you actually see the seals, or the empty packaging with part numbers you verified?

            Also if your forks are still "pitted" as one of your other older threads indicates then you will not likely get a good enough seal for the air to stay in, and in all likely hood your seals won't last very long either.
            1979 xs1100 Special -
            Stock air box/K&N Filter, MAC 4-2 exhaust, Bad-Boy Air horn, TC fuse box, Windshield, Soft bags, Vetter Fairing, Blinkers->Run/Turn/Brake Lights, Headlight Modulator, hard wire GPS power

            Short Stack - 1981 xs1100 Standard - lowered for SWMBO.

            Originally posted by fredintoon
            Goes like a train, corners like a cow, shifts like a Russian tractor, drinks like a fish, you are gonna love it.
            My Bike:
            [link is broken]

            Comment


            • #7
              Leaking air caps

              When I replaced the fork seals on my special the fork air caps have a thin o-ring that can be pinched if tightened down incorrectly. You may be able to unscrew the caps a bit to see if they're there w/o removing the forks though you'd have to loosen the upper fork pinch bolt.

              Darrell
              Darrell
              78E
              80G project
              06FJR

              Comment


              • #8
                Likely that the grooves - which I think the shop made in the first place(the forks were clean and smooth when I got it) - are not holding the airs...When a mechanic who re-did the seals. I provided the fork oil and fork seals.

                From now on, I will do all the works on the bike myself...I shouldn't have been discouraged by three flights of stairs to bring my tool boxes down and sandy carport floor...
                dontlikeoc
                1981 XS1100 Special Edition
                Alhambra, CA

                Comment

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