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Help Identifying Correct Jets on a 77 GS750

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    Help Identifying Correct Jets on a 77 GS750

    Previous owner had pods, and a shop re-jet the carbs with 115 main jets I put the stock air box back on, and I'm looking to replace the main jet with a genuine Mikuni jet in the stock size. So poke around to see what I can learn here, and then I head over to Bass Cliffs site and read through the chart on OEM jets sizes, and learn that the early 750's had different jetting depending on when it was made. The frame tag said it was manufactured 7/76. and I have pics of the stamped numbers on the engine and frame in the link below. I must be looking at the wrong numbers since I didn't see those corresponding numbers, so I thought I would go the other way and check the pilot jet size. I pull the pilot jet, and it's a #20 Mikuni jet. Now this is where I get really lost since according to the chart on Bass Cliffs site that should be 22.5 or 27.5. I know for the main jet I need either 105 of 97.5, but do I also need to look for new pilot jets? Would I need a 22.5 or a 27.5 pilot jet?
    20211121_133026.jpg

    Here's a link to a few more pics of the carbs. https://imgur.com/a/kJDk7Ja

    #2
    This thread posted a while back has a service bulletin that may be of help:
    1978 GS 750 E
    1979 XS11 Standard
    1973 CB450

    Comment


      #3
      Originally posted by Forden View Post
      This thread posted a while back has a service bulletin that may be of help:
      https://www.thegsresources.com/_foru...in-From-Suzuki
      Thanks. Where would I find the numbers on the carb they reference, like 45010 or 45011?

      Comment


        #4
        The carb reference number is on the carb flange where it bolts to the back plate.
        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

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          #5
          Thanks for your help!

          Comment


            #6
            The factory manual says 100 main and 15 pilot. The main can be bumped to 102.5 and the pilot to 17.5 if needed. With Suzuki's VM's there is a lot of tuning available through the pilot screws though so jet changes shouldn't be needed unless you have modified the bike.
            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


              #7
              The carb ID number will be here on the #4 carb. It’ll be faint but it’s there. DA6D64AA-4915-46DB-91BB-E1B16397CD96.jpg
              1978 Suzuki GS750

              Past bikes owned:
              1978 Suzuki GS750E, 1979 Suzuki GS750E, 1980 Suzuki GS850, 1977 Suzuki GS550, 1969 Honda CB350, 1976 Harley Davidson SS175, 1979 Motobecane 50V, 1978 Puch Maxi, 1977 Puch Newport, 1980 Tomos Bullet, 1978 Motobecane 50VLA, 1978 AMF Roadmaster

              Comment


                #8
                Originally posted by mattd1205 View Post
                The carb ID number will be here on the #4 carb. It’ll be faint but it’s there. [ATTACH=CONFIG]63615[/ATTACH]
                This was a huge help. I was having trouble finding it on the flange. I found it now, and confirmed them to be 45020oZ4N1Lr - Imgur.jpg

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