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Round metal disc with screws inside the master brake cylinder

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  • Round metal disc with screws inside the master brake cylinder

    Fellow yammies, I tore down both master brake cylinders today. I am missing the metal round pieces in BOTH OF THEM. No wonder the pistons wouldn't pop back out.

    I'm reaching out to all of you to sell me your extra pieces with the screws or send me to a source where I can buy them. I need 2 discs and 4 screws.
    ​​​​​​

  • #2
    Originally posted by 80xs11socali View Post
    Fellow yammies, I tore down both master brake cylinders today. I am missing the metal round pieces in BOTH OF THEM. No wonder the pistons wouldn't pop back out.

    I'm reaching out to all of you to sell me your extra pieces with the screws or send me to a source where I can buy them. I need 2 discs and 4 screws.
    ​​​​​​
    If you can you need to show pictures of what you say you are missing. I am not aware of a metal disc with screws in the master cylinder. Here is a schematic of the front master ... identify which piece you are missing. Yamaha Motorcycle 1980 OEM Parts Diagram for FRONT MASTER CYLINDER | Partzilla.com
    2 - 80 LGs bought one new
    81 LH
    02 FXSTB Nighttrain
    Jim

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    • #3
      I know my post is confusing. Here's a screen grab from youtube video. I think this holds the plastic reservoir to the master cylinder.

      Thank you.

      Comment


      • #4
        Originally posted by 80xs11socali View Post
        I know my post is confusing. Here's a screen grab from youtube video. I think this holds the plastic reservoir to the master cylinder.

        Thank you.
        Where did you get the video. None of my master cylinders have ever had that disc in them. On the xs11's there is a large o ring that seals the plastic reservoir to the base. The screws that secure the lid and other components are generally long enough to extend through the reservoir all the way to the metal base on the fronts and there a four screws that extend up through on the rears with bolts on top. If you do have a master like you see in the video then it is something that was bought and put on. Maybe someone more knowledgeable then me can chime in if I am not correct. If you have original XS11 masters then the appropriate rebuild kit for your year and model of bike should suffice to get you going. That is unless you have severe pitting etc... going on. Have you checked to be sure the spooge holes are open and working properly. If not search the maintenance section on brakes and there is a thread on them and how to clean.
        2 - 80 LGs bought one new
        81 LH
        02 FXSTB Nighttrain
        Jim

        Comment


        • #5
          The older style 78-79 front masters have that disk.
          The screws that hold the top cover on are short and do not pass thru the fluid reservoir on the 78-79. The disk and it's 2 screws hold the reservoir tight to the metal body.
          Last edited by bikerphil; 04-24-2021, 05:34 PM.
          2H7 (79)
          3H3

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          • #6
            Originally posted by bikerphil View Post
            The older style 78-79 front masters have that disk.
            The screws that hold the top cover on are short and do not pass thru the fluid reservoir on the 78-79. The disk and it's 2 screws hold the reservoir tight to the metal body.
            Interesting. When I researched all the schematics on Partzilla for the 78-79 standards there was no indication of that disc being present. At least it isn't shown as a replaceable part. Thanks for the update.
            2 - 80 LGs bought one new
            81 LH
            02 FXSTB Nighttrain
            Jim

            Comment


            • #7
              Seems like a better design than the later years.

              Mine are prone to leaking around the bottom of the reservoir, so I have to pull them apart, replace the O-ring, and repaint them every 10 years.
              -Mike
              _________
              '79 XS1100SF 20k miles
              '80 XS1100SG 42k miles
              '81 XS1100H Venturer 35k miles
              '79 XS750SF 20k miles
              '85 Honda V65 Magna ~7k miles
              '84 Honda V65 Magna 48k miles (parts bike)
              '86 Yamaha VMAX 7k miles

              Previous: '68 Motoguzzi 600cc + '79 XS750SF 22k miles +'84 Honda V65

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              • #8
                I'm so confused. LoL

                I'll post pictures tomorrow.

                Comment


                • #9
                  Originally posted by cajun31 View Post

                  Where did you get the video. None of my master cylinders have ever had that disc in them. On the xs11's there is a large o ring that seals the plastic reservoir to the base. The screws that secure the lid and other components are generally long enough to extend through the reservoir all the way to the metal base on the fronts and there a four screws that extend up through on the rears with bolts on top. If you do have a master like you see in the video then it is something that was bought and put on. Maybe someone more knowledgeable then me can chime in if I am not correct. If you have original XS11 masters then the appropriate rebuild kit for your year and model of bike should suffice to get you going. That is unless you have severe pitting etc... going on. Have you checked to be sure the spooge holes are open and working properly. If not search the maintenance section on brakes and there is a thread on them and how to clean.
                  Cajun, where do you source the o ring that goes between the plastic reservoir to the base?

                  Comment


                  • #10
                    Originally posted by 80xs11socali View Post

                    Cajun, where do you source the o ring that goes between the plastic reservoir to the base?
                    That O ring generally is not bad to the point of actually falling to pieces. I have never had to replace it and honestly I think you would have to probably find something close. If you reservoir is not leaking around the base then it is probably ok. The problem with them leaking starts when you pry to reservoir off of the base. You will need to do that by the way to gain access to the spooge hole that I mentioned in my previous post. It sounds like you have the later master because you do not have the metal disc in yours. Your cap screws are probably long enough to actually screw down into the base. What I do is use a thin layer of yamabond on the base after I clean the spooge hole if I experience brake fluid seepage after reassembly. No guarantees that I might not have to clean that spooge hole again in the future so I may have to disassemble again in the future. On the later masters once you have them apart to the point of having to separate the plastic reservoir from the base you can actually turn it slightly by hand while on the base to give you better access to remove it from the base. That is why I said put a light coat of yamabond when sealing it so that it doesn't make the future job of removing it again if necessary. I do believe the root of your problem right now is that those spooge holes are clogged. The symptom of your brakes not releasing is what indicates that and is what the spooge hole does.
                    2 - 80 LGs bought one new
                    81 LH
                    02 FXSTB Nighttrain
                    Jim

                    Comment

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