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Help identifying strange VM26 markings.

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    Help identifying strange VM26 markings.

    I am restoring a set of VM26SS carbs from a USA imported GS1000, for some strange reason they have been bored out and had a stainless steel sleeve fitted. The ID of the sleeve is exactly 26mm. All 4 carbs have this sleeve so it is a deliberate modification, rather than a repair job on 1 carb.
    You can clearly see the sleeve in the attached picture. I cant think of a reason why this has been done, and i have never seen it on any other set of VM's i have restored in the past.



    A possible clue is that apart from the usual carb ID number stamped on the flange (49010), on the other side of the flange there is 7 Z1 stamped on it.



    Has anyone seen this before, is it a mod that is carried out by someone in the USA?
    It clearly isn't going to be an issue with the carb operation, i am merely intrigued to find out the reasoning behind it.

    TIA
    1978 GS1085.

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

    #2
    I can't say that I've seen that modification before.
    But, there is a guy who would make your carbs flow more air - Maxi Bore was his process
    1978 GS 1000 (since new)
    1979 GS 1000 (The Fridge, superbike replica project)
    1978 GS 1000 (parts)
    1981 GS 850 (anyone want a project?)
    1981 GPZ 550 (backroad screamer)
    1970 450 Mk IIID (THUMP!)
    2007 DRz 400S
    1999 ATK 490ES
    1994 DR 350SES

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      #3
      Could it be somebody sleeved down some 28s' for some reason? Not really GS original fitment?
      I had that set of Kawasaki rack if you remember that were identical to GS kind except the air screw adjustment was absent.
      sigpic

      Don't say can't, as anything is possible with time and effort, but, if you don't have time things get tougher and require more effort.

      Comment


        #4
        Originally posted by tatu View Post
        Could it be somebody sleeved down some 28s' for some reason? Not really GS original fitment?
        I had that set of Kawasaki rack if you remember that were identical to GS kind except the air screw adjustment was absent.
        The ID number on the carbs suggest they are Suzuki original VM26's.The bore at the venturi measures 26mm so they had to be 26's to begin with. They have both air and fuel pilot screws.
        Last edited by Agemax; 11-20-2021, 05:15 PM.
        1978 GS1085.

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

        Comment


          #5
          A pic and measurement of the carb mouth would help.
          If they have been bored out to 28 or 30mm in the past then the mouth will also be 28 or 30mm and the sleeve has been used on the engine side to return them to stock ( although stock 26's are actually closer to 27mm at the boot side).
          If the mouth appears stock then the sleeves are there to repair damage or some other unknown reason to one or more of the carbs and all have been done to maintain matching flow between them all.
          Mikuni Viton Choke Plunger Seat Renewal.
          VITON Choke plunger seals .KAWASAKI Z1,Z900,Z650,Z1000,Z1R,SUZUKI GS1000,GSXR,RF | eBay

          Air Corrector Jets for Mikuni VM 24, 26 and 28mm carbs .
          https://www.ebay.co.uk/itm/254380193...84.m1555.l2649



          sigpic

          Comment


            #6
            Originally posted by zed1015 View Post
            A pic and measurement of the carb mouth would help.
            If they have been bored out to 28 or 30mm in the past then the mouth will also be 28 or 30mm and the sleeve has been used on the engine side to return them to stock ( although stock 26's are actually closer to 27mm at the boot side).
            If the mouth appears stock then the sleeves are there to repair damage or some other unknown reason to one or more of the carbs and all have been done to maintain matching flow between them all.
            As i said, they measure 26mm, so they haven't been bored out larger.
            It makes sense that have have all been sleeved so they all match but there is no obvious reason why. I think the clue is in the 7 Z1 stamped on them, i have never seen this before.
            1978 GS1085.

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

            Comment


              #7
              Originally posted by Agemax View Post
              As i said, they measure 26mm, so they haven't been bored out larger.
              It makes sense that have have all been sleeved so they all match but there is no obvious reason why. I think the clue is in the 7 Z1 stamped on them, i have never seen this before.
              The 7 Z1 was most likely put there by the person who sleeved the carbs.
              No kawasaki ever had VM26 or 28mm carbs with both fuel and air screw as stock so they are original Suzuki fitment, either GS750, 850 or 1000.
              If they are stock on the airbox side then the sleeve is either to repair a damaged carb and the others were done to match or they have been altered for another reason.
              If it wasn't to repair damage, all the sleeves would do is maintain a slightly higher velocitiy in the carb body as the originals tapered out to the boot side to almost 27mm.
              There is another possibility that the rack has been made up of mismatched bodies of which they have used two or more with the port in the bore wall for a vacuum tap and have done this to block them off but if this was the case there will be additional mods , drillings and blanking plugs to make those bodies suitable for their new position.
              Last edited by zed1015; 11-21-2021, 03:51 PM.
              Mikuni Viton Choke Plunger Seat Renewal.
              VITON Choke plunger seals .KAWASAKI Z1,Z900,Z650,Z1000,Z1R,SUZUKI GS1000,GSXR,RF | eBay

              Air Corrector Jets for Mikuni VM 24, 26 and 28mm carbs .
              https://www.ebay.co.uk/itm/254380193...84.m1555.l2649



              sigpic

              Comment


                #8
                I know they are Suzuki carbs because of the ID numbers. They are all otherwise untouched and unmodified. The sleeve does not go far enough to interfere with the vacuum port in #3 carb, they are all the same length and go in as far as the original "step" in the throat where it changes from 26 to 27(ish)mm.
                Because its a USA import bike i was wondering if any of the USA members had ever come across the 7 Z1 id stamp or a clue as to who, or what company it may have been.
                1978 GS1085.

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

                Comment


                  #9
                  I'm no mechanist, but that seems like a lot of trouble to repair a carb that should be readily available & easily replaced. Those carbs were used on several bikes for several yrs...But looks like a nice job.
                  1983 GS1100E, 1983 CB1100F, 1991 GSX1100G, 1996 Kaw. ZL600 Eliminator, 1999 Bandit 1200S, 2005 Bandit 1200S, 2000 Kaw. ZRX 1100

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