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Float height higher than 25.7 mm?

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  • Float height higher than 25.7 mm?

    So I pulled the carbs off Succubus, checked them (ooooh, clean), reset the float height and remounted them. Put the tank back on. Figure I'll go back and check the plugs in the morning.

    Morning came. I start to leave for work. What's that? Smells like gas. Really expensive free range gasoline. Wild and free gasoline. Go out into the garage. Smells like a Molotov cocktail. I notice a small gorge cut into my garage floor from the flow of really expensive gasoline.

    Really expensive gasoline. As expensive as that ridiculous bottled water my beloved bride must buy. The stuff that's STILL more expensive than gasoline. The stuff that is no better than the cheap water that comes out of several taps in and around our house. The stuff that just comes out of other taps in municipal water systems nationwide. The ridiculous scam....

    But I digress.

    My floats were set at a perfect 25.7 mm. So perfect that NASA called and asked to use my float height as the basis for a new measuring system. I refused. I don't need anything else named after me. One African village is enough. Long story.

    Anyway, I'm thinking I have to go higher. Maybe 27, 28 mm. Maybe a couple inches. Old floats. Maybe bent.

    Is everybody really married to the idea of stock float height? Anybody go higher?

    Patrick
    The glorious rays of the rising sun exist only to create shadows in which doom may hide.

    XS11F (Incubus, daily rider)
    1969 Yamaha DT1B
    Five other bikes whose names do not begin with "Y"

  • #2
    Did you bench test the floats to see if they
    were hung up upon re-assembly?
    Didn't think so. Quite common for the floats to hang. At least the first time. Usually they clear with a sharp rap on the bodies. However if they drop too far, they will hang on the float bodies. Check that too.
    John
    Now: '78 XS1100E 750 FD Mod (Big Dog)
    '81 CB900C ( 10 Speed)
    '78 CB750F ( The F)
    '76 CB400F ( The Elf)
    New '82 Honda MB5 Ring Ding
    Then: '76 CB550K
    '78 CB750F
    '84 VF1100S
    And still Looking!

    Comment


    • #3
      Before I put the bowls back on I flipped the carbs upright and worked the floats. No signs of hanging. I set the tangs on the back of the float so that the floats could just drop far enough to allow the needles to open. They could still be hanging, but I saw nothing that would make me expect that.

      Patrick
      The glorious rays of the rising sun exist only to create shadows in which doom may hide.

      XS11F (Incubus, daily rider)
      1969 Yamaha DT1B
      Five other bikes whose names do not begin with "Y"

      Comment


      • #4
        Try it with the bowls on. Sometimes makes a difference, I've found. When I say hanging floats, I mean on the side of the float bowls. (With them installed obviously)
        Still, try them with fuel on the bench and see. Also after having done all the everything before re-installing my carbs, on several occasions, the first time fuel is applied to the carbs after installation, they or it, frequently leaks. After the first episode, after turning off fuel and letting them rest, they work fine. Slow floats?
        Never have figured that one out.
        John
        Now: '78 XS1100E 750 FD Mod (Big Dog)
        '81 CB900C ( 10 Speed)
        '78 CB750F ( The F)
        '76 CB400F ( The Elf)
        New '82 Honda MB5 Ring Ding
        Then: '76 CB550K
        '78 CB750F
        '84 VF1100S
        And still Looking!

        Comment


        • #5
          The height of the floats shold only set the 'final' level of fuel inside the float bowls. It would highly unusual to get the floats set so low (i.e. high when turned right side up) tht the fuel level would be high enough to leak out.

          More likely something is hanging up, or the float valves have wee bits of dirt in them, or the spring loaded plunger on the end of the float valve is catching on a burr or worn spot on the tang that pushed against it. Or, on later-style carbs with press-in float valve seats, the o-ring around the body is shot.
          Ken Talbot

          Comment


          • #6
            Succubus:

            After many removals and checking, including new floats, and seats, and valves, also new jets in between the removals, also bench checking adjusting floats, adjusting float height using Ken Talbots method of sight gages' I would get the floats to stop sticking for ten to fifteen tries of empting the bows and refilling. I would then put them back on the bike after empting them and hooking up the tank, the floats would stick again. Off the bike again go through the exercise again, back on the bike.

            Examining what could possibly happen, I examined the floats in detail and concluded that the swing of the floats just a few millimeters would cause them to bottom out in the bowl edge. Also the new gaskets that I used had a lip on them when I cinched down the float bowl. This would also cause the float to stick on the down stroke when empty. If you check the arc swing of the floats in relation to the bowl design, The bowl sides do not allow much arc swing. Also there is much side play of the floats that will allow the floats to swing left and right, increasing the arc swing of one of the float balls.

            I concluded that the proper way was to trim the lip off of the gasket , bend the back tang of the floats almost parallel, so that the float would drop only a couple of millimeters. This would eliminate the arc swing bottoming out where the drag of the bowl would lock them in place. (parasitic drag). You only have to allow the needles to just drop out of the seats to get flow, and under normal driving conditions the floats do not drop very far as gravity is continually filling the bowl as the fuel is used. Re- set the float drop and be sure that the side swing is not allowing one ball to swing outside the clearance drop.

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