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A Broken Valve Shim and It's Aftermath

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    #46
    Originally posted by blowerbike View Post
    production cost?
    That would be my guess. Cheaper to make them without the chamfer.

    1980 GS1000GT (Daily rider with a 1983 1100G engine)
    1998 Honda ST1100 (Daily long distance rider)
    1982 GS850GLZ (Daily rider when the weather is crap)

    Darn, with so many daily riders it's hard to decide which one to jump on next.

    JTGS850GL aka Julius

    GS Resource Greetings

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      #47
      The first thing I thought when I saw my Z1 shims was through carburising. I don't know even if that is how they are hardened. I no longer have access to a metlab but if I did and a broken shim came across my path I would slip in there and prep it and etch for case depth. I would be concerned if the effective case depth were more than 1/3 of the shim thickness. After that I would be looking for diffusion on the grain boundaries and retained Austenite and and and........ Just saying
      Anyone know a lab with a back door that accepts beer tokens.
      97 R1100R
      Previous
      80 GS850G, 79 Z400B, 85 R100RT, 80 Z650D, 76 CB200

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        #48
        Goddamn, you're a met-head labrat.
        It never lets go.
        ---- Dave
        79 GS850N - Might be a trike soon.
        80 GS850T Single HIF38 S.U. SH775, Tow bar, Pantera II. Gnarly workhorse & daily driver.
        79 XS650SE - Pragmatic Ratter - goes better than a manky old twin should.
        92 XJ900F - Fairly Stock, for now.

        Only a dog knows why a motorcyclist sticks his head out of a car window

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          #49
          Originally posted by Grimly View Post
          Goddamn, you're a met-head labrat.
          It never lets go.
          This is true. Fortunately I learned that some of the longest life parts when checked at end of life would fail on book criteria for structure and cleanliness. There is no substitute for hands on experience and beating suppliers over the head with an ASME chart is foolish. However there are some lines you don't cross and one of them is case hardening a part to the extent that it has no residual core toughness left to absorb the slings and arrows of real life.
          97 R1100R
          Previous
          80 GS850G, 79 Z400B, 85 R100RT, 80 Z650D, 76 CB200

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            #50
            Did a couple of years as a trainee met-head labrat with British Steel, right after leaving school. I've forgotten a lot of it, but it was wild and exciting stuff at that age, plodding around the iron and steel works taking samples and doing the analysis real-time for production processes.
            Some of my lifetime best pics were taken then. If only I had the kit then that I do now, I could really have done it justice.
            ---- Dave
            79 GS850N - Might be a trike soon.
            80 GS850T Single HIF38 S.U. SH775, Tow bar, Pantera II. Gnarly workhorse & daily driver.
            79 XS650SE - Pragmatic Ratter - goes better than a manky old twin should.
            92 XJ900F - Fairly Stock, for now.

            Only a dog knows why a motorcyclist sticks his head out of a car window

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              #51
              Bumping this back up in the hope of gathering some more information.

              Jeff from Z1 mentioned problems with K&L valve shims in the same timeframe as this thread. http://www.thegsresources.com/_forum...21#post2185821

              I've got a bunch of brand new K&L shims and wondering if there is any definitive way to test them? I checked a bunch of shims on a hardness tester and found a couple that were softer than the others by a fair bit so I'm going to throw those away. Wondering if that's good enough or do I need to do something else?
              Ed

              To measure is to know.

              Mikuni O-ring Kits For Sale...https://www.thegsresources.com/_foru...ts#post1703182

              Top Newbie Mistakes thread...http://www.thegsresources.com/_forum...d.php?t=171846

              Carb rebuild tutorial...https://gsarchive.bwringer.com/mtsac...d_Tutorial.pdf

              KZ750E Rebuild Thread...http://www.thegsresources.com/_forum...0-Resurrection

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                #52
                The one that broke on me was an OEM shim. I never had any problems with k&l shims, but that could have been just luck of the draw

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                  #53
                  Originally posted by Nessism View Post
                  Bumping this back up in the hope of gathering some more information.

                  Jeff from Z1 mentioned problems with K&L valve shims in the same timeframe as this thread. http://www.thegsresources.com/_forum...21#post2185821


                  I've got a bunch of brand new K&L shims and wondering if there is any definitive way to test them? I checked a bunch of shims on a hardness tester and found a couple that were softer than the others by a fair bit so I'm going to throw those away. Wondering if that's good enough or do I need to do something else?

                  That shim in post #39 and the ones Steve pictured looks to be too hard. Softer shims would probably just wear more and not shatter.
                  Also any grit or grime under the shim would cause a properly heat treated shim to fail as well.
                  Last edited by AMK; 06-27-2017, 09:59 PM. Reason: Afterthought
                  Alan

                  sigpic
                  Weaned on a '74 450 Honda
                  Graduated to an '82 GS850GL
                  Now riding an '83 GS1100GL
                  Added an '82 GS1100GL

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                    #54
                    spicoli.jpg

                    I knew I had something for this.

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