What do you think about my clearances?

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  • c3powil
    • Jan 2026

    #1

    What do you think about my clearances?

    I pulled my valve cover today and started checking clearances for the first time ever. this is what I found:

    Exhaust#4- 2.70 shim (between .051 and .063)
    Exhaust#3- 2.75 shim (between .063 and .051)
    Exhaust#1- Unknown shim size (between .051 and .038)
    Exhaust#2- 2.75 shim (between .076 and .108)

    Intake#1- 2.70 shim (between .038 and .051)
    Intake#2- 2.70 shim (between .038 and .051)
    Intake#3- 2.70 shim (between .038 and .051)
    Intake#4- 2.70 shim (between .038 and .051)

    I've ordered new half moons and Real Gaskets. Do you think these specs are okay to leave or should I consider ordering shims? I know that the clearance specs are between 0.03 and 0.08 millimeters, but I'm thinking of whats best for my bike in the next 3000 miles till my next clearance check.
  • tkent02
    Forum LongTimer
    Past Site Supporter
    • Jan 2006
    • 35571
    • Near South Park

    #2
    They are all in spec, barely. I'd button it up and ride, but order the shims you need and fix it when they get there. That's the beauty of Realgaskets, you can open it up lots of times without any leaking.

    To figure out what you ned in Ex 1, can you measure the thickness with a micrometer or calipers? If not, swap with Ex #2 which you know and measure the clearance, you can figure it out from there.
    http://img.photobucket.com/albums/v5...tatesMap-1.jpg

    Life is too short to ride an L.

    Comment

    • c3powil

      #3
      Originally posted by tkent02
      They are all in spec, barely. I'd button it up and ride, but order the shims you need and fix it when they get there. That's the beauty of Realgaskets, you can open it up lots of times without any leaking.

      To figure out what you ned in Ex 1, can you measure the thickness with a micrometer or calipers? If not, swap with Ex #2 which you know and measure the clearance, you can figure it out from there.
      Thanks for the tip! I have calipers that I use to measure carb float levels, but they don't get that accurate. I can tell it is around the 2.7ish mark, but not much more than that.

      Also, is reusing old half moons generally accepted? Whats the risk?
      Last edited by Guest; 03-24-2014, 09:08 PM.

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      • Grimly
        Forum Guru
        Past Site Supporter
        Super Site Supporter
        • Sep 2012
        • 5761
        • Ireland

        #4
        Originally posted by c3powil

        Also, is reusing old half moons generally accepted? Whats the risk?
        I got caught out yesterday with the old half-moons and had no choice but to re-use them. Totally forgot to order a new set up. The old ones were hard but went back in with a smear of Hylomar and crossed fingers. So far, so good. On the other hand, I got stranded once when a half-moon popped out on the road and oil spewed all down my leg. Had to get picked up and recovered home on a truck. That was a fairly new one and was replaced by the shop that did my clearances at that time. Couldn't prove anything and it wasn't worth falling out with them over it.
        Dave
        '79 GS850GN '80 GS850GT
        Only a dog knows why a motorcyclist sticks his head out of a car window

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        • bwringer
          Forum LongTimer
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          • Oct 2003
          • 17066
          • Indianapolis

          #5
          Do not use new half-moon seals with a Realgasket.

          New half-moon seals are intended to be used with a stock cardboard gasket. They stick up a fair bit when first installed, and the gasket mashes them in place.

          A Realgasket is thicker and softer, and it cannot apply the necessary pressure to properly seat new half-moon seals. The seals will stick up, the gasket will leak at the corners of the seals, and the half-moons will very likely slide out and release a spectacular amount of oil onto your leg.

          Smear a light whisper of sealer (not RTV if you can help it) on the curved surfaces of your old half-moons and re-install them. They'll be fine, really.
          1983 GS850G, Cosmos Blue.
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          Comment

          • c3powil

            #6
            Thanks for that tip!

            Comment

            • earlfor
              Forum LongTimer
              Charter Member
              GSResource Superstar
              Past Site Supporter
              • May 2002
              • 42410
              • off grid cabin 1/24/26 7pm

              #7
              Valves set with a little to much gap will not hurt anything, but run a little bit noisier.
              Valves set too tight (insufficient clearance) are a BIG no no.
              Komorebi-The light filtering through the trees.

              I would rather sit on a pumpkin and have it all to myself than be crowded on a velvet cushion. H.D.T.

              Comment

              • c3powil

                #8
                Originally posted by earlfor
                Valves set with a little to much gap will not hurt anything, but run a little bit noisier.
                Valves set too tight (insufficient clearance) are a BIG no no.
                How much is a little too much? I know that some of my clearances are between 3 and 5mm, if I bumped up the clearances to a maximum of 10mm, would that hurt? Im asking because I could only find shims in 2.65mm and if I installed these into the valve buckets that were between 3 and 5mm there is a risk of having a max clearance of 10mm.

                Also, my Realgaskets and half moons just came in. Since the new half moons wont work with the Realgaskets, should I send them back, or consider keeping them for some reason?

                Comment

                • tkent02
                  Forum LongTimer
                  Past Site Supporter
                  • Jan 2006
                  • 35571
                  • Near South Park

                  #9
                  .10mm is fine, a lot of us use .10mm as the upper limit.
                  http://img.photobucket.com/albums/v5...tatesMap-1.jpg

                  Life is too short to ride an L.

                  Comment

                  • c3powil

                    #10
                    Originally posted by tkent02
                    .10mm is fine, a lot of us use .10mm as the upper limit.
                    Great! I suppose I'll wait until the shims get here to button up the top since the weather has been a bit cold lately.

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                    • earlfor
                      Forum LongTimer
                      Charter Member
                      GSResource Superstar
                      Past Site Supporter
                      • May 2002
                      • 42410
                      • off grid cabin 1/24/26 7pm

                      #11
                      Originally posted by c3powil
                      How much is a little too much? I know that some of my clearances are between 3 and 5mm, if I bumped up the clearances to a maximum of 10mm, would that hurt? Im asking because I could only find shims in 2.65mm and if I installed these into the valve buckets that were between 3 and 5mm there is a risk of having a max clearance of 10mm.

                      Also, my Realgaskets and half moons just came in. Since the new half moons wont work with the Realgaskets, should I send them back, or consider keeping them for some reason?

                      I would send the Realgasket back and use a stock gasket
                      Komorebi-The light filtering through the trees.

                      I would rather sit on a pumpkin and have it all to myself than be crowded on a velvet cushion. H.D.T.

                      Comment

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