Carb swap/Custom carb setup

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  • puna_trav
    • Mar 2026
    #1

    Carb swap/Custom carb setup

    First post. I know, noob, blah blah.
    I've got an '81 GS550t with all the classic CV carb problems. I bought it as a basket case for $200 from a drunk guy down the street. I cleaned the hell out of the stock carbs, but they are just too far gone. One of them is JB welded together, and at best I can get it to run on 4 cylinders sporadically.

    I'm looking at replacing them with something else with a cable operated slide. I have a lot of experience with scooters, and one of the most popular carbs to use are Koso style flat slide carbs. Most of what I've found about retrofitting the CV carbs refers to using the round-bore Mikunis that came on earlier models. I found a set of flat slide 32mm Koso's dirt cheap on flea-bay that are new, and a '69 cb750 4-carb cable to link 'em together. Before I bite the bullet and actually order the carbs, I was curious if anyone has any experience using this style of carburetor on a GS550?


    I'm not afraid of Kustom action, but at the same time, if there is some glaring incompatibility that I'm missing, I'd like to know. Here's a current picture... still lots to be done.
    Attached Files
    Tags: None
    • puna_trav
      #2
      Figure I aught to add a link to the carbs I'm looking at. http://www.ebay.com/itm/PWK-Koso-32-...bef58b&vxp=mtr

        Comment

        • Agemax
          Forum Guru
          • Apr 2008
          • 8371
          • plymouth uk
          #3
          you might struggle to find 40mm inlet rubbers that will fit your 550
          1978 GS1085.

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

            Comment

            • puna_trav
              #4
              These carbs had the same size port on the intake side as the mikuni CVs that came on the bike... I ordered a single carb to experiment with, I suppose I'll find out in a week or two when they arrive.

                Comment

                • Steve
                  GS Whisperer
                  • Jun 2005
                  • 35927
                  • southwest oHIo
                  #5
                  Where are you? There are a few of us here that work on carbs, we might have some spare parts or even a spare body to replace your botched carbs.

                  .
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                  #2 son: 1980 GS1000G
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                    Comment

                    • puna_trav
                      #6
                      Originally posted by Steve
                      Where are you? There are a few of us here that work on carbs, we might have some spare parts or even a spare body to replace your botched carbs.

                      .
                      I'm on the big island of Hawaii. I would rather just do away with the CVs altogether at this point, since I've had nothing but trouble so far. Almost all of them have crossthreaded jets from the PO, clogged idle circuits and one has a broken float support. I would need at least two carb bodies to possibly get them working... thanks for the offer, though.

                        Comment

                        • JJ
                          #7
                          It would be much easier, and probably less expensive in the long run, to buy some used CV carbs and rebuild them.

                            Comment

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