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  • Float Post Repair alternative.

    So today I decided to repair a float post. No2 carb had a broken float post on the SG I bought (which I knew when I purchased it). When I opened the carb, the break was actually pretty nasty looking.



    It had run decent with the condition, but I had that one carb flooding after the clean up I had done, so rather than wait and see if it cleared up I decided to fix it.

    Now I had always planned to use a shoulder bolt, thread it into the post that remained, and cut flat spots in it and drill a hole, so once it was threaded in, it would work as a float post. Well, it just so happens that I have a spare carb body for the 80-81 style carbs with stripped out threads in the mix screw tower. So I consider it scrap material. Thinking this out a bit, I decided to cut off the float post close to the reinforcing rib from the needle valve “tower”. Then cut the carb to be repaired in a similar place, such that after allowing for the width of the blade, the two would join to be the same height.

    After carefully cutting both post, I center punched the carb body, and drilled a hole for a 8-32 tap. Then tapped out the hole as best I could. Then put the screw into the hole.


    Next was to tap the piece of float post. To do that, I took a piece of wood, and drilled holes to match the stepped down top section so it pushed in and was solidly mounted. Now I drilled and tapped that piece. After measuring how deep the bolt went into each piece, I knew how long to cut the bolt to. Now I threaded it into the top piece of the post.


    Of course, next step is to thread it into the body section.



    The discerning eye will notice it does not 100% align, but it is dang close. If I did this again, I would use a drill press instead of hand drill. So, now I have a almost factory float post again, it works great, Go the float installed, height set, and the movement is good.
    Life is what happens while your planning everything else!

    When your work speaks for itself, don't interrupt.

    81 XS1100 Special - Humpty Dumpty
    80 XS1100 Special - Project Resurrection


    Previously owned
    93 GSX600F
    80 XS1100 Special - Ruby
    81 XS1100 Special
    81 CB750 C
    80 CB750 C
    78 XS750

  • #2
    Before I read your text, it looked like you turned down and threaded the new post.But you actually tapped both pieces and used all-thread. Very nice work Don.
    80 SG XS1100
    14 Victory Cross Country

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    • #3
      Beautifully done. Machinist workmanship with hand tools. A solid reliable repair.
      "Little by little the look of the country changes because of the men we admire." Hud

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      • #4
        So I guess the treads were just right so that the snug position aligned the hole exactly perfect. or did you use thread lock or something else?
        Skids (Sid Hansen)

        Down to one 1978 E. Stock air box with K&N filter, 81H pipes and carbs, 8500 feet elevation.

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        • #5
          Well, the camera is not that great, it is not a perfect snug fit. There is some gaps, but very small. When I was tapping the holes I did try to align the cutting of the threading from one hole to another, but in reality that is just dumb luck where the tap catches the material and starts cutting its thread. My initial plan was that any gaps would be filled with plumbing solder and then filed/sanded smooth. However, there is not enough gap to worry about in my opinion.

          when I threaded it on, it tightened until the two pieces met, and then I tightened a little further to align the flat side of the tower. It took a crescent wrench on the tower flat sides to turn it into position, but not allot of force.

          I did not use thread locker. I would thing fuel would eat it anyway. Reality is that the float pin will keep it from turning, and when the pin is out, nothing will cause it to turn or loosen. At least that is my theory.
          Life is what happens while your planning everything else!

          When your work speaks for itself, don't interrupt.

          81 XS1100 Special - Humpty Dumpty
          80 XS1100 Special - Project Resurrection


          Previously owned
          93 GSX600F
          80 XS1100 Special - Ruby
          81 XS1100 Special
          81 CB750 C
          80 CB750 C
          78 XS750

          Comment


          • #6
            Nice job. That is a very good repair method providing you have a junk carb body to sacrifice. If not, a post could probably be fabricated from a bolt shank if need be.
            2H7 (79) owned since '89
            3H3 owned since '06

            "If it ain't broke, modify it"

            Comment


            • #7
              Interestingly enough, I started off drilling and tapping a hole in the carb body of the junk carb. I have a bolt I am working on to make it a float post. I will get pictures and post when I finish it.
              Life is what happens while your planning everything else!

              When your work speaks for itself, don't interrupt.

              81 XS1100 Special - Humpty Dumpty
              80 XS1100 Special - Project Resurrection


              Previously owned
              93 GSX600F
              80 XS1100 Special - Ruby
              81 XS1100 Special
              81 CB750 C
              80 CB750 C
              78 XS750

              Comment


              • #8
                Great job, probably the best method I've ever seen. And I've saw many broken posts since 1981, some on brand new bikes.
                "We are often so caught up in our destination that we forget to appreciate the journey." "

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                • #9
                  I think even if the tab was not tightened down -(because the index would be wrong when tightened) it would be fine. The fact that the float pin fits in the hole thus prevents rotation and the float bowl prevents the pin from walking out on either side. Well done!

                  Comment


                  • #10
                    Originally posted by mharrington View Post
                    I think even if the tab was not tightened down -(because the index would be wrong when tightened) it would be fine. The fact that the float pin fits in the hole thus prevents rotation and the float bowl prevents the pin from walking out on either side. Well done!
                    I would be concerned that if the 'new' post isn't tight that vibration could 'erode' the threads out of either the post or the carb body. Maybe some fuel-proof glue like fuel tank epoxy is called for....
                    Fast, Cheap, Reliable... Pick any two

                    '78E original owner - resto project
                    '78E ???? owner - Modder project FJ forks, 4-piston calipers F/R, 160/80-16 rear tire
                    '82 XJ rebuild project
                    '80SG restified, red SOLD
                    '79F parts...
                    '81H more parts...

                    Other current bikes:
                    '93 XL1200 Anniversary Sportster 85RWHP
                    '86 XL883/1200 Chopper
                    '82 XL1000 w/1450cc Buell, Baker 6-speed, in-progress project
                    Cage: '13 Mustang GT/CS with a few 'custom' touches
                    Yep, can't leave nuthin' alone...

                    Comment


                    • #11
                      How about just drilling a hole in the body and the post and force them together using a split pin?
                      2H7 (79) owned since '89
                      3H3 owned since '06

                      "If it ain't broke, modify it"

                      Comment


                      • #12
                        Originally posted by bikerphil View Post
                        How about just drilling a hole in the body and the post and force them together using a split pin?
                        I think that (along with some sort of adhesive) would be better...
                        Fast, Cheap, Reliable... Pick any two

                        '78E original owner - resto project
                        '78E ???? owner - Modder project FJ forks, 4-piston calipers F/R, 160/80-16 rear tire
                        '82 XJ rebuild project
                        '80SG restified, red SOLD
                        '79F parts...
                        '81H more parts...

                        Other current bikes:
                        '93 XL1200 Anniversary Sportster 85RWHP
                        '86 XL883/1200 Chopper
                        '82 XL1000 w/1450cc Buell, Baker 6-speed, in-progress project
                        Cage: '13 Mustang GT/CS with a few 'custom' touches
                        Yep, can't leave nuthin' alone...

                        Comment


                        • #13
                          I wanted it threaded as I had thought out if my cutting was not accurate, I could use the threading to adjust the height of the hole, which is why I used the high thread count. I imagined I would have a gap of exposed thread, and planned to fill it with solder. It just turned out I was more accurate than I anticipated.

                          Here is an alternative method, in case you do not have a scrap carb to cut up. I used a shoulder bolt I had laying around. Basically, I trimmed and cut it down to match a float post. I used the scrap carb body I cut the float post off of to demonstrate this method.

                          I started by cutting the head off the bolt, then used my “redneck lathe” ( a metal file in a vise and the bolt in a drill) to get the threaded section down to the 5mm-.08 thread I put in the carb body.


                          After I got it machined down, I threaded the bolt. To get the thread all the way to the quasi-shoulder I made, I turned the die over so the small end was the leading edge.


                          Then I threaded it into the carb body and marked how deep it threaded in. I used this length to cut the length of the bolt down.


                          With it threaded into place, I transferred the dimensions from the existing float post to the one I made. After some reasonably careful cutting with a Dremel cutoff wheel, I had it formed. The shoulder were not the same but the inner one was deep enough I did not try to even them out. Then I marked the critical dimension of the hole center, and drilled the hole. Here it is with the float installed. Float moves freely, and bowl fits well.



                          I would guess you could leave the outside alone, and not cut the shoulder into it. Another alternative fix. Tools used were the hand drill, dremel cutoff wheel, a metal file, and a 5mm-.8 tap and die.
                          Life is what happens while your planning everything else!

                          When your work speaks for itself, don't interrupt.

                          81 XS1100 Special - Humpty Dumpty
                          80 XS1100 Special - Project Resurrection


                          Previously owned
                          93 GSX600F
                          80 XS1100 Special - Ruby
                          81 XS1100 Special
                          81 CB750 C
                          80 CB750 C
                          78 XS750

                          Comment


                          • #14
                            Originally posted by crazy steve View Post
                            I think that (along with some sort of adhesive) would be better...

                            Comment


                            • #15
                              Originally posted by crazy steve View Post
                              I would be concerned that if the 'new' post isn't tight that vibration could 'erode' the threads out of either the post or the carb body. Maybe some fuel-proof glue like fuel tank epoxy is called for....
                              A way to ensure the the post doesn't move is to 'ding' up the threads of the bolt a little creating an interference fit. It can't vibrate loose that way. No thread lock needed. JAT
                              2H7 (79) owned since '89
                              3H3 owned since '06

                              "If it ain't broke, modify it"

                              Comment

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