Valve Shim Size Questions...

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  • Stahlgrau333
    Forum Mentor
    • Mar 2011
    • 641
    • Norman, OK
    #1

    Valve Shim Size Questions...

    Checked the clearances on my valves this past weekend, and it turns out that 7 out of 8 of my valves have 'negative' clearance...could not spin the tappet at all on the back side of the lobe. My measurements were:

    I1 - 2.70 - <0
    I2 - 2.65 - <0
    I3 - ?? No Number - <0
    I4 - 2.60x - <0

    E1 - 2.60 - <0
    E2 - 2.60 - .05mm
    E3 - 2.70 - <0
    E4 - 2.65x - <0

    Obviously, they're way out of spec. My guess is that they've never been adjusted before (bike has ~ 21k miles on it).

    My questions are, first, how many sizes should I go down on the 7 that need adjusted? Should I go down one shim, or two? Doing a search here on the forum leads me to believe I should go down 2 sizes, I just want to confirm before I do so.

    Second question is, what's the difference between a 'normal' size shim (ie, 2.65) and an 'x' size (ie, 2.65x)? Are they interchangeable, or do I need to do something special with those valves?

    Apologies if these are stupid questions, just want to make sure it's done right...
    1982 GS1100GL (Sold :()(Retrieved!:pray:)
    1978 GS1000C (Sold, to be revived by Chuck)
    1979 GS1000EN (Parts Whore)
    1979 GS1000C (Collecting Dust)
    1980 GS750E (Sport-Touring Build...Someday?)
    1981 GS750L (Abandoned Project...maybe?)
    1982 GS750E (Collecting Dust)
    1983 GS750T (This is becoming a problem...)
    1981 GS650GL (Parts Whore / Cafe Donor)
    1981 GS550L (Cafe Project)
    Tags: None
    • Guest
      #2
      Shims

      I believe you are correct in trying 2 sizes below the existing shims and may end up wanting a half step lower. The X designation seems to cover a shim that is outside the spec for a standard shim. ie: a 2.60 shim appears to have a range of 2.59 to 2.61 when new thus a 2.60X will likely be 2.62 or 2.63. At least that is what I have observed to be the case. Ray

        Comment

        • Agemax
          Forum Guru
          • Apr 2008
          • 8371
          • plymouth uk
          #3
          buy,borrow,steal a 2.50 shim and fit it in each position. then measure the gap with your guages and work out what size shim is required
          1978 GS1085.

          Just remember, an opinion without 3.14 is just an onion!

            Comment

            • Nessism
              Forum LongTimer
              GSResource Superstar
              Past Site Supporter
              Super Site Supporter
              • Mar 2006
              • 35790
              • Torrance, CA
              #4
              I'd order 5 each of sizes 2.55, 2.50, 2.45. Z1 Enterprises sells shims for about $5 each. They won't go to waste and you will have what you need for the next two checks, maybe longer. After that, trade shims with Ray to get what you need.
              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

                • cowboyup3371
                  Forum LongTimer
                  Past Site Supporter
                  • Apr 2010
                  • 13996
                  • In Ohio Now
                  #5
                  Two words - Steve's Spreadsheet.

                  Send him an email and it will help you figure that out.
                  Cowboy Up or Quit. - Run Free Lou and Rest in Peace

                  1981 GS550T - My First
                  1981 GS550L - My Eldest Daughter's - Now Sold
                  2007 GSF1250SA Bandit - My touring bike

                  Sit tall in the saddle Hold your head up high
                  Keep your eyes fixed where the trail meets the sky and live like you ain't afraid to die
                  and don't be scared, just enjoy your ride - Chris Ledoux, "The Ride"

                    Comment

                    • rustybronco
                      Forum LongTimer
                      Bard Award Winner
                      GSResource Superstar
                      Past Site Supporter
                      • Jul 2005
                      • 14961
                      • Marysville, Michigan
                      #6
                      After adjusting your valve clearances I have three words for you... leak down test.

                      Here's a link to a roll you own version> http://www.motorcycleproject.com/mot.../leakdown.html

                      the reason to check cylinder leak down you say? how about this... http://thegsresources.com/_forum/sho...3&postcount=64
                      De-stinking Penelope http://thegsresources.com/_forum/sho...d.php?t=179245

                      http://www.thegsresources.com/_forum...35#post1625535

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