1981 GS650g carb problems

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  • Petcol
    Forum Newbie
    • Nov 2025
    • 2
    • Saskatoon, Saskatchewan, Canada

    #1

    1981 GS650g carb problems

    Hi all, I have a serious problem, just bought 1981 gs650 g shaft drive, been stood for 21/2 years ran to start with but now wont run, have taken carbs off and noticed that jet seat on number 1 carb is much lower than the other 3 how do I fix this?
    Second question, one of the float posts is broken off, looks like it's been stuck back on with some sort of adhesive, the bottom of the break is sticky with something, any ideas how to fix this or do I need to buy another carb?
    I should mention that they are Mikuni bs32ss carbs fitted to my bike.
    Thanks
    Last edited by Petcol; 11-07-2025, 04:36 PM. Reason: forgot to mention what carbs are on the bike
  • jdub6092
    Forum Mentor
    Super Site Supporter
    • Nov 2023
    • 250
    • Gilbert, Arizona

    #2
    If you are referring to the needle jet and seat, it's possible that it was replaced with an unmatched set. I saw this when I used the original mikuni jet and a seat from a rebuild kit and noticed the height difference. Ended up using both pieces from the rebuild kit to correct.

    I haven't had an issue with a carb post, but I did watch a video on a post repair.

    Last edited by jdub6092; 11-08-2025, 01:26 PM.
    1981 GS650E Stardust Silver

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    • jdub6092
      Forum Mentor
      Super Site Supporter
      • Nov 2023
      • 250
      • Gilbert, Arizona

      #3
      Here is the difference in needle jet sizes between the Mikuni and K&L rebuild kit. The seat is higher so when matched the total height is the same.
      1762627424390444457172238315039.jpg​Experts on this forum do not recommend the K&L rebuild kit.
      1981 GS650E Stardust Silver

      Comment

      • maxredline
        Forum Newbie
        • Mar 2024
        • 9
        • "The Island", BC Canada

        #4
        Can you find a BS32ss carb body as a replacement for your float issue?
        I would try here and Facebook GS groups

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        • Nessism
          Forum LongTimer
          GSResource Superstar
          Past Site Supporter
          Super Site Supporter
          • Mar 2006
          • 35787
          • Torrance, CA

          #5
          Buy a new set of float valves. Real deal mikuni or Keyster brand.

          And a new carb body to replace the one with the broken float post.

          In the carb rebuild tutorial linked in my signature, I show how to remove the float pin without breaking the post off. Sadly, many people don't research, and lack basic mechanical knowledge, thus there are lots of broken posts.
          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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          • Mr.humbucker
            Forum Mentor
            Past Site Supporter
            • Nov 2012
            • 296
            • British Columbia

            #6
            Let me know which carb has the broken post and I'll check and see if I have a replacement for you. I am in BC so mailing it is pretty easy.
            GS550T 1981
            GS850G 1983
            GS650G 1982
            GS650G 1982 Under Restoration 😳🏍👍

            Comment

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

              #7
              This guy on eBay claims to have #1 carb body from gs650



              best to assume the worst and fully/properly all the carbs….some folks can be creative
              1981 gs650L

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

              Comment

              • Petcol
                Forum Newbie
                • Nov 2025
                • 2
                • Saskatoon, Saskatchewan, Canada

                #8
                Hi again, I've come across a complete bank of all 4 carbs, they will obviously need cleaning, question is, do I take them apart first, or put them in a sonic cleaner before and then strip them?

                Comment

                • Nessism
                  Forum LongTimer
                  GSResource Superstar
                  Past Site Supporter
                  Super Site Supporter
                  • Mar 2006
                  • 35787
                  • Torrance, CA

                  #9
                  Originally posted by Petcol
                  Hi again, I've come across a complete bank of all 4 carbs, they will obviously need cleaning, question is, do I take them apart first, or put them in a sonic cleaner before and then strip them?
                  Follow the rebuild tutorial. Full teardown. Carb dip >>> ultrasonic.
                  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

                  • Mr.humbucker
                    Forum Mentor
                    Past Site Supporter
                    • Nov 2012
                    • 296
                    • British Columbia

                    #10
                    Several good videos on YouTube on dismantling these carbs. Go slow and follow the tutorial. Make sure your screw driver you use to remove the air fuel mixture screw is a full tight fit to the slot head as the screw heads are often difficult to remove or loosen and they easily deformed making them near impossible to get out if damaged.
                    ​​​​
                    Heat helps as does even firm downward pressure on the screw driver.
                    GS550T 1981
                    GS850G 1983
                    GS650G 1982
                    GS650G 1982 Under Restoration 😳🏍👍

                    Comment

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