GS450 compression check?

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  • Trevor76

    #1

    GS450 compression check?

    Okay I searched. Really I did, and couldn't find anything.

    So...How do you check the compression on a GS450, or any electric start motorcycle for that matter?

    I know how on a kickstart bike -take out the plug, screw the compression gauge in, open the throttle and kick the bejeezus out of it until the needle stops rising.

    But what about a e-start only bike?

    And for that matter, what numbers are within spec for the '80 GS450?
    The Clymer makes no mention of it...

    Thanks.
  • tom203
    Forum Guru
    Past Site Supporter
    • Aug 2010
    • 8925
    • Norway,Maine

    #2
    "I know how on a kickstart bike -take out the plug, screw the compression gauge in, open the throttle and kick the bejeezus out of it until the needle stops rising."

    Say what? why not just pretend you're kickstarting it as you press starter button?
    1981 gs650L

    "We are all born ignorant, but you have to work hard to stay stupid" Ben Franklin

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    • Nessism
      Forum LongTimer
      GSResource Superstar
      Past Site Supporter
      Super Site Supporter
      • Mar 2006
      • 35811
      • Torrance, CA

      #3
      Before you can do a proper compression test the engine must be hot. And since most GS owners don't believe in maintenance, adjusting the valves is critical because there is a good probability some of the valves are not properly seated. Also, if the bike has sat for some time you can't get a good compression estimation because the rings often get sticky as the bike has sat in storage - compression will increase after some miles.

      Good luck
      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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      • niclpnut
        Forum Sage
        Past Site Supporter
        • Sep 2010
        • 1274
        • Peculiar, MO

        #4
        One hot, I like to hook up my Battery tender when I do a compression test so the battery doesnt get drained down.

        Nic
        83 GS1100ES rebuild:

        http://www.thegsresources.com/_forum...d.php?t=170032

        Budget GSXR Conversion:

        http://www.thegsresources.com/_forum...d.php?t=200563

        New to me bike: 2008 B-KING

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        • DaveR
          Forum Sage
          Past Site Supporter
          • Nov 2010
          • 2404
          • Saskatchewan Canada

          #5
          Originally posted by Nessism
          ..most GS owners don't believe in maintenance..
          That's a grand statement Mr Nessism, is it really true?
          1979 GS1000
          1981 GL500 Interstate

          Comment

          • Pendulum

            #6
            Originally posted by DaveR
            That's a grand statement Mr Nessism, is it really true?

            It seems to me that if the owner isn't a member here... Then yes, it's probably true.

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            • Nessism
              Forum LongTimer
              GSResource Superstar
              Past Site Supporter
              Super Site Supporter
              • Mar 2006
              • 35811
              • Torrance, CA

              #7
              Originally posted by Nessism
              And since most GS owners don't believe in maintenance, adjusting the valves is critical because there is a good probability some of the valves are not properly seated.
              Originally posted by DaveR
              That's a grand statement Mr Nessism, is it really true?
              Should have said "many" instead of "most".

              Even of the members here on GSR, I'll bet at least 25% of them don't adjust their valves.
              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

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