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    carbtune question

    I have used the morgan carbtune pro twice or three times before. It was easy enough. I have since made some adjustments to my carbs and it was feeling lumpy so I decided I would take a look at the sync.

    Problem was the carbtune wouldnt register anything below say 3500 rpm. I am so sure I didnt sync them last time at 4000 rpm. At 1500-2500 the metal rods stayed firmly at the bottom. Not sure what would cause that?

    Vacuum line was plugged and I dont have any leaks.

    My plugs look great the bike runs awesome but I cannot nail this idle. At first it needs choke for about 2 miles and will stall out if I let it at lights until I have about 5 miles. I tweak the throttle some to make sure it doesnt stall. Then it will idle at 1200 pretty nicely but once it gets good and hot when I pull up to a light it will hang at 2000 for up to 20-30 seconds and then drop down to 1200.

    I figured it taking that long to warm up and needing choke so long that it maybe needed to be a bit richer so I turned the screw up 1/4 turn. I am now at 3 1/4 turns on each screw.

    Like i said .. bike runs good and strong ... I just cant nail the idle. I may have to admit defeat and see if I can find a local mechanic
    Last edited by Guest; 10-07-2017, 03:50 PM.

    #2
    Don’t be afraid to go another 1/4 turn. Tune each carb individually, they won’t necessarily all be the same.

    When the rods won’t move off the bottom, turn the gauge over, so the vacuum now pulls the rods DOWN, against their springs. I learned that trick by reading the directions.

    .
    sigpic
    mine: 2000 Honda GoldWing GL1500SE and 1980 GS850G'K' "Junior"
    hers: 1982 GS850GL - "Angel" and 1969 Suzuki T250 Scrambler
    #1 son: 1986 Yamaha Venture Royale 1300 and 1982 GS650GL "Rat Bagger"
    #2 son: 1980 GS1000G
    Family Portrait
    Siblings and Spouses
    Mom's first ride
    Want a copy of my valve adjust spreadsheet for your 2-valve per cylinder engine? Send me an e-mail request (not a PM)
    (Click on my username in the upper-left corner for e-mail info.)

    Comment


      #3
      Do you have new carb boots? Hanging idle is a classic symptom of a vacuum leak.
      Charles
      --
      1979 Suzuki GS850G

      Read BassCliff's GSR Greeting and Mega-Welcome!

      Comment


        #4
        alrighty steve ... I felt like an idiot so I went and reread the instructions and Problems FAQ but I dont find anything about using the gauge upside down.

        Carbtune motorcycle carburetor synchronizers;polycarbonate tool pouchs;for motorcyclists




        So I will ask since you are one of the carb heros here.... Are you suggesting holding it upside down to use or just turning it upside down and then back to right side up. They have Maintenance instructions that involve inverting but I just cant find instruction on using it if the rods don't rise.

        I have my weird idle squared away, bike runs well but I know it is in need of a sync to get it perfect.

        When I was a kid they had a program called RIF. Reading is fundamental .. maybe it failed me!

        Comment


          #5
          No you hang it upside down and sync with it in that position.
          Jordan

          1977 Suzuki GS750 (My first bike)
          2000 Kawasaki ZRX1100
          1973 BMW R75/5

          Comment


            #6
            Originally posted by Boriqua View Post
            alrighty steve ... I felt like an idiot so I went and reread the instructions and Problems FAQ but I dont find anything about using the gauge upside down.

            https://www.carbtune.com/inst.html
            At the top of the page, under 'Description', fourth paragraph down:

            To get a reading below 8cmHg remove the plastic cable clip from the slot at top of gauge and insert it into the slot at the bottom. Push cable clip into slot from front of gauge. Hang the Carbtune Pro upside-down.
            Ignore the scale figures. Zero will now be around 16cmHg on the scale but the full width scale graduations will still be 2cmHg. Absolute values are not important. Comparisons are important.

            Mark
            1982 GS1100E
            1998 ZX-6R
            2005 KTM 450EXC

            Comment


              #7
              Originally posted by Boriqua View Post
              alrighty steve ... I felt like an idiot so I went and reread the instructions and Problems FAQ but I dont find anything about using the gauge upside down.

              Carbtune motorcycle carburetor synchronizers;polycarbonate tool pouchs;for motorcyclists




              So I will ask since you are one of the carb heros here.... Are you suggesting holding it upside down to use or just turning it upside down and then back to right side up. They have Maintenance instructions that involve inverting but I just cant find instruction on using it if the rods don't rise.
              Originally posted by hannibal View Post
              No you hang it upside down and sync with it in that position.
              Originally posted by mmattockx View Post
              At the top of the page, under 'Description', fourth paragraph down:
              Mark
              Thank you, hannibal and Mark.

              .
              sigpic
              mine: 2000 Honda GoldWing GL1500SE and 1980 GS850G'K' "Junior"
              hers: 1982 GS850GL - "Angel" and 1969 Suzuki T250 Scrambler
              #1 son: 1986 Yamaha Venture Royale 1300 and 1982 GS650GL "Rat Bagger"
              #2 son: 1980 GS1000G
              Family Portrait
              Siblings and Spouses
              Mom's first ride
              Want a copy of my valve adjust spreadsheet for your 2-valve per cylinder engine? Send me an e-mail request (not a PM)
              (Click on my username in the upper-left corner for e-mail info.)

              Comment


                #8
                Thank you EVERYONE! I dont know how i missed that ... several times ... but it will come in handy because saturday is sync day. I didnt even know there was a hanger slot on the bottom?!

                I am sure I cant have been the only person that ran into this .. maybe .. so its good info to have up here for future searches.
                Alex

                Comment


                  #9
                  "Searches"??? You can SEARCH on this forum???

                  What will they think of next?



                  .
                  sigpic
                  mine: 2000 Honda GoldWing GL1500SE and 1980 GS850G'K' "Junior"
                  hers: 1982 GS850GL - "Angel" and 1969 Suzuki T250 Scrambler
                  #1 son: 1986 Yamaha Venture Royale 1300 and 1982 GS650GL "Rat Bagger"
                  #2 son: 1980 GS1000G
                  Family Portrait
                  Siblings and Spouses
                  Mom's first ride
                  Want a copy of my valve adjust spreadsheet for your 2-valve per cylinder engine? Send me an e-mail request (not a PM)
                  (Click on my username in the upper-left corner for e-mail info.)

                  Comment

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