1981 GS 650 Carb Compatibility

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  • wl1150
    Forum Newbie
    • May 2024
    • 2
    • Brooklyn, NY

    #1

    1981 GS 650 Carb Compatibility

    Hey all, was just gifted a 650 E as a project and it came without carbs. I've been researching trying to figure out how to replace them and I know it used 4 32mm Mikuni carbs. It is very hard to find a replacement set so I was wondering what my options are in terms of getting carbs that will fit? I don't care at all about originality, just want to get the bike running well without spending an arm and a leg. Any suggestions in terms of compatibility? I think the gs550 carbs are the same, but are there other options? Different brands? New vs old, any option I will consider. Any help would be greatly appreciated. Hoping for some expertise here!
    -W
  • unfocused
    Forum Mentor
    Past Site Supporter
    • Jul 2019
    • 384
    • St. Augustine, FL

    #2
    All 16v small bore engines should run the same 32mm Mikuni carbs - internals are the only thing that change - jetting, needles and such. My memory is vague here as I haven dealt much with the 16v engines.
    Current:
    1993 ZX11 - 2nd build in progress
    1977 GS750 (710 is getting closer)
    1998 Kawasaki Voyager - selling
    1998 Chevy C2500
    1999 Rav4

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    • wl1150
      Forum Newbie
      • May 2024
      • 2
      • Brooklyn, NY

      #3
      Thanks for the reply! That is helpful info. Much appreciated.

      Comment

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

        #4
        The first gen 550 CV carbs are very similar. The jetting is different. And there may be differences in how the throttle and choke cables work. There are other GS bikes using BS32 carbs, but they won't fit due to differences in the carb spacing.
        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

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

          #5
          This set looks salvageable…with a proper cleaning…some jetting maybe be different though

          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
            • 35787
            • Torrance, CA

            #6
            Originally posted by tom203
            This set looks salvageable…with a proper cleaning…some jetting maybe be different though

            https://www.ebay.com/itm/23547435604...mis&media=COPY
            NO NO NO. That set has a broken float post! NO!

            "No visible cracks or damage" says the seller! BS alert!
            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

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

              #7
              I've seen worse. The price is right. As long as they aren't all torn up, they are fixable.

              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

              • Rich82GS750TZ
                Forum Guru
                Past Site Supporter
                Super Site Supporter
                • Jun 2018
                • 5568
                • Mifflinburg, PA / Land of Tar & Chip

                #8
                Originally posted by Nessism

                NO NO NO. That set has a broken float post! NO!

                "No visible cracks or damage" says the seller! BS alert!
                Good eye, Ed………
                Links

                Comment

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

                  #9
                  “No visible cracks or damage" says the seller! BS alert!“

                  be gentle, he did say they were for “parts only”….90% complete!
                  those frosted cards from other seller likely to have hidden surprises.
                  didn’t someone on here post a link to float post repair? Maybe OP is the creative type!
                  1981 gs650L

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

                  Comment

                  • Ecampolo
                    Forum Newbie
                    • Apr 2021
                    • 8
                    • Largo FL

                    #10
                    550 carbs use different jets, emulsion tubes and needes. 550 CV's can work but jetting could be complicated, there is a MAJOR difference in the 550 / 650 needles and emulsion tubes, 550 were drasticly more tapper in the needles and a shielded emulsion tube top. If using 550 carbs I'd start with a jet kit from six sigma using 650 as the base carb spec and start on the lean end for mains as when the slide rises on a 550 the 50 / 60 % opening has a 35 to 40% narrower taper, 550 stock main were 92.5 and 650 were 97.5 , pilot were 40 on the 550 nd 42.5 on the 650. My guess dialing in the mid range with 550 carbs will be a pain. 550's were notioriously lean with the CV's, and raising the needles to get into the taper sooner helped dramitically. The 650 makes way more power everywhere and the TDCC has different intake velocity.

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