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    Leaking Float Bowl Overflow Tubes

    I'm rebuilding a set of Keihin CV34 carbs from a KZ750/4 and struggling with leaking out the overflow tubes. Found that the overflow tube was cracked on three of four carbs, now fixed by soldering, only one of the tubes is also leaking where it goes though the hole in the float bowl.

    The 1980 version of these carbs have functional overflow tubes, and for the 1981 model year the feature was deleted. I've seen some later year float bowls without the tubes and others with the tubes only the nipple on the bottom of the float bowl wasn't drilled. The set I'm working on are actually the later, only some knucklehead (me) drilled out the nipple making the overflow functional (bad idea). Well, maybe not a bad idea per say only now I've got leaking that needs to be fixed.

    I'm thinking about the following options to fix the carbs:

    - Use fuel tank sealer around the leaking tube. I've got access to some high tech aircraft tank sealer stuff that's state of the art (P/S 890 Proseal).

    - Cut off the tubes and plug the hole in the float bowl with...something. Any ideas?

    - Replace the tubes.

    Any suggestions?


    Last edited by Nessism; 04-13-2017, 12:10 AM.
    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

    #2
    Pull the tube out, tap the hole and use a small screw and fibre washer.
    '84 GS750EF (Oct 2015 BOM) '79 GS1000N (June 2007 BOM) My Flickr site http://www.flickr.com/photos/soates50/

    Comment


      #3
      I would prefer to have overflow going outside than in.
      Is the problem that the fourth tube is cracked too close to (or inside )the housing to get solder on it ?
      Could that tube be simply turned around to get the crack into clear air.
      Only thing about sealer in there is it better be the good stuff 'cause you know where it's headed if it starts to break up.
      97 R1100R
      Previous
      80 GS850G, 79 Z400B, 85 R100RT, 80 Z650D, 76 CB200

      Comment


        #4
        Originally posted by Brendan W View Post
        I would prefer to have overflow going outside than in.
        Agree. That's why I made the tubes functional in the first place.

        Did a leak test and bubbles come up from right where the tube enters the float bowl. Most likely the crack extends down into the float bowl.

        Found a little tutorial on how to replace the tubes. Think I'll try this before trying to plug the hole...http://cx500forum.com/forum/general-...placement.html
        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


          #5
          The only thing I would add is a tad bit if heat on the bowl part when pressing in the tube.
          That was an excellent tutorial.
          Alan

          sigpic
          Weaned on a '74 450 Honda
          Graduated to an '82 GS850GL
          Now riding an '83 GS1100GL
          Added an '82 GS1100GL

          Comment


            #6
            Yeah I was impressed with the work.
            97 R1100R
            Previous
            80 GS850G, 79 Z400B, 85 R100RT, 80 Z650D, 76 CB200

            Comment


              #7
              The CX500 tutorial worked a treat! Piece of cake!

              Used the dimple on the side of a threading die to help roll over the lip on the tubing to shrink the hole size. Flared the tubing OD using a drill on the inside just like the tutorial.

              One down. Now I'm going to do the other tubes that I brazed. This fix is better...

              Ain't the internet great!
              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


                #8
                The dimple on the die is a stroke of genius also.
                Alan

                sigpic
                Weaned on a '74 450 Honda
                Graduated to an '82 GS850GL
                Now riding an '83 GS1100GL
                Added an '82 GS1100GL

                Comment


                  #9
                  Factory on the right, homemade on the left.


                  P1030567 by nessism, on Flickr
                  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


                    #10
                    Have you checked for leaks?? Put a piece of vacuum hose on the bottom and fill the bowl with water and blow on the hose. Any leaks will make bubbles on the inside.
                    MY BIKES..1977 GS 750 B, 1978 GS 1000 C (X2)
                    1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550

                    NEVER SNEAK UP ON A SLEEPING DOG..NOT EVEN YOUR OWN.


                    I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.

                    Comment


                      #11
                      Yes, checked for leaks. The new tubes are fine.
                      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


                        #12
                        Nice work, Ed.
                        Where did you get the new tubing? Hobby shop?
                        2@ \'78 GS1000

                        Comment


                          #13
                          Hobby shops that cater to the RC crowd will have it. I actually had a few pieces left over from when I used to fly RC. My local ACE hardware had some too. K&S is the common brand.
                          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


                            #14
                            Originally posted by Nessism View Post
                            Hobby shops that cater to the RC crowd will have it. I actually had a few pieces left over from when I used to fly RC. My local ACE hardware had some too. K&S is the common brand.
                            Two signs you are over 50.
                            Using punctuation in texts and saying RC instead of drone.
                            Kids these days are merciless.
                            97 R1100R
                            Previous
                            80 GS850G, 79 Z400B, 85 R100RT, 80 Z650D, 76 CB200

                            Comment


                              #15
                              Today's project was making a fuel Tee. Salty_Monk (Dan) loaned me his mini lathe and I did the rest...

                              P1030580 by nessism, on Flickr
                              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

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