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29.5mm shims don't fit my 850

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    #1

    29.5mm shims don't fit my 850

    I'm into the first valve adjustment on my '79 850 and found the exhaust side to be way loose (worst was up to .23mm). I ordered shims from Z1 to correct them all and bring them back into spec and now have those in hand. Trying to fit them this morning and found they won't fit in the buckets. Didn't think to measure the diameter before ordering and now the 29.5mm shim doesn't fit, I've measured both with my caliper. Sure enough the shims in there are 29mm diameter, kind of explains why the new one's don't fit but now I'm confused as to why they aren't 29.5mm shims.

    What does use 29mm shims? I'm now suspecting the head may have been swapped at some point.

    Any other ideas?

    Thanks as always.
    It's smoke that make electronic components work.
    Every time I've let the smoke out by mistake, they never work again.
    '80 GS250T... long gone... And back!
    '86 Honda Bol D'Or... very sadly long gone
    '82 GS1000SZ
    '82 GS1100GL
    '01 Honda CBR1100XX BlackBird
    Tags: None
    #2
    29mm shims are for Kawasaki's. Do the 29mm shims fit tightly in the valve bucket? If so, someone swaped your buckets for Kawasaki buckets. Not good.

    How about posting some photos?
    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

    Comment

      #3
      Just been having a closer look, the 29mm shims are not a tight fit. Raises the question how tight a fit should the shim be? I figured there should be some play but maybe not. I'll go see if I can get a better idea of what gap there is between bucket and shim. If it's .5mm I might get a bit more forceful putting the shim in.

      Should they be a tight fit?
      It's smoke that make electronic components work.
      Every time I've let the smoke out by mistake, they never work again.
      '80 GS250T... long gone... And back!
      '86 Honda Bol D'Or... very sadly long gone
      '82 GS1000SZ
      '82 GS1100GL
      '01 Honda CBR1100XX BlackBird

      Comment

        #4
        Originally posted by Wallowgreen View Post
        Just been having a closer look, the 29mm shims are not a tight fit. Raises the question how tight a fit should the shim be? I figured there should be some play but maybe not. I'll go see if I can get a better idea of what gap there is between bucket and shim. If it's .5mm I might get a bit more forceful putting the shim in.

        Should they be a tight fit?
        Tight fit yes, it's often necessary to pry them out with a small screwdriver blade. Sounds like some idiot stuck KZ shims in the regular GS buckets. Use the proper size or a shim may get spit out at high rpm.
        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

        Comment

          #5
          Maybe I'm just not being forceful enough with the new shims! If I turn the bucket so the notch is accessible, I can get a 0.5mm feeler in easily between the shim and bucket lip.

          Going to try again...
          It's smoke that make electronic components work.
          Every time I've let the smoke out by mistake, they never work again.
          '80 GS250T... long gone... And back!
          '86 Honda Bol D'Or... very sadly long gone
          '82 GS1000SZ
          '82 GS1100GL
          '01 Honda CBR1100XX BlackBird

          Comment

            #6
            Ok Ed, I have to admit it looks like I'm a bit of a wus!

            Looked at all the shims in their buckets, some have a gap to the bucket, some don't. I figure whoever did the last adjustment used the wrong diameter shims probably because that's what they had.

            Had another go at fitting the 29.5mm shim in ex1 and with a little gentle persuasion it went in. I was worried about getting it in there and never being able to get it out again.

            I suppose I'll need to replace all those that look loose to be on the safe side.

            Panic over... whew!!
            It's smoke that make electronic components work.
            Every time I've let the smoke out by mistake, they never work again.
            '80 GS250T... long gone... And back!
            '86 Honda Bol D'Or... very sadly long gone
            '82 GS1000SZ
            '82 GS1100GL
            '01 Honda CBR1100XX BlackBird

            Comment

              #7
              Went round the shims again measuring the diameter this time as well. Turns out six of the eight were 29mm diameter, only thought I needed to change three so now I have to wait for another three to get here.

              Don't know who did the work last time but it's peed me off a little. Wanted to move on to the next thing preventing #1 from firing consistently. Was hoping to find something wrong with the valve adjustments on #1 but sadly nothing particular to that pot. Oh well...
              It's smoke that make electronic components work.
              Every time I've let the smoke out by mistake, they never work again.
              '80 GS250T... long gone... And back!
              '86 Honda Bol D'Or... very sadly long gone
              '82 GS1000SZ
              '82 GS1100GL
              '01 Honda CBR1100XX BlackBird

              Comment

                #8
                Better to find out now than when doing 9K rpm's

                Comment

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