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  • Float Height

    The Yamaha service manual specifies a float height of 24.7mm +/- 1mm or 24.7-26.7mm. On the set that I have rebuilt, a height of 24.7 will, ever so slightly, weep fuel on all 4. I am thinking of going to the 25.7 or 26.7 height to stop the leaking. Has anyone set floats at the 26.7mm height?
    1981 XS1100H Venturer
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    ACCT
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    Limie Accent Moves On In 2015

    Mike

  • #2
    Originally posted by MPittma100 View Post
    The Yamaha service manual specifies a float height of 24.7mm +/- 1mm or 24.7-26.7mm. On the set that I have rebuilt, a height of 24.7 will, ever so slightly, weep fuel on all 4. I am thinking of going to the 25.7 or 26.7 height to stop the leaking. Has anyone set floats at the 26.7mm height?
    The manuals state 25.7 +/- 1mm. 25.7 seems to be about perfect and if it changes too much it does make it leaner or richer depending on the direction.
    Nathan
    KD9ARL

    μολὼν λαβέ

    1978 XS1100E
    K&N Filter
    #45 pilot Jet, #137.5 Main Jet
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    ATK Fork Brace
    LED Dash lights
    Ammeter, Oil Pressure, Oil Temp, and Volt Meters

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    In any moment of decision the best thing you can do is the right thing, the next best thing is the wrong thing, and the worst thing you can do is nothing.

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    • #3
      With the fuel we call gas out here, I set floats to 27mm. The ethanol in the fuel makes it lighter, and the floats do not act the same as with 100% petroleum. I made a gauge from an old credit card, and use it on all the floats. With it, I can set all 8 floats exactly the same.
      Ray Matteis
      KE6NHG
      XS1100 E '78 (winter project)
      XS1100 SF Bob Jones worked on it!

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      • #4
        Drop them .5mm. If that doesn't do it go another .5.
        Greg

        Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.”

        ― Albert Einstein

        80 SG Ol' Okie;79 engine & carbs w/pods, 45 pilots, 140 mains, Custom Mac 4 into 2 exhaust, ACCT,XS850 final drive,110/90/19 front tire,TKat fork brace, XS750 140 MPH speedometer, Vetter IV fairing, aftermarket hard bags and trunk, LG high back seat, XJ rear shocks.

        The list changes.

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        • #5
          Originally posted by MPittma100 View Post
          The Yamaha service manual specifies a float height of 24.7mm +/- 1mm or 24.7-26.7mm. On the set that I have rebuilt, a height of 24.7 will, ever so slightly, weep fuel on all 4. I am thinking of going to the 25.7 or 26.7 height to stop the leaking. Has anyone set floats at the 26.7mm height?
          If you replaced the float needles with other than Mikuni(K&L,etc.), you may find that the internal spring collapes farther than the Mikuni ones causing floats to raise a bit more upon shut-down, causing a slight weep around bowls. Had this happen on the 'evil#3' carb, and found that that particualr K&L float needle compressed farther than the rest, raising float and fuel level upon shut-down.......always figured that was why K&L had five instead of four in a package......better odds of similarilty maybe.
          Last edited by motoman; 02-12-2015, 01:07 PM.
          81H Venturer1100 "The Bentley" (on steroids) 97 Yamaha YZ250(age reducer) 92 Honda ST1100 "Twisty"(touring rocket) Age is relative to the number of seconds counted 'airing' out an 85ft. table-top.

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          • #6
            Originally posted by DiverRay View Post
            With the fuel we call gas out here, I set floats to 27mm. The ethanol in the fuel makes it lighter, and the floats do not act the same as with 100% petroleum. I made a gauge from an old credit card, and use it on all the floats. With it, I can set all 8 floats exactly the same.
            Ray, did you cut the credit card even to measure from the center rib of the gasket mating surface?
            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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            • #7
              Ray, did you cut the credit card even to measure from the center rib of the gasket mating surface?
              Yes, it's cut in a big "L" shape so it will fit between carbs/floats. I go from left to right, measuring each float. I just flip the gauge over to measure from the left side, and then the right side of the carb body.
              Ray Matteis
              KE6NHG
              XS1100 E '78 (winter project)
              XS1100 SF Bob Jones worked on it!

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              • #8
                Another Ex. of a float gauge

                This one I made from an old float bowl gasket, for my '80G carbs:





                ]
                1980 XS1100G "Dolly G" Full Dresser (with a coat of many colors )
                1979 XS1100SF (stock-euro mods planned)
                1984 XV700L Virago (to be hot-modded)
                1983 XJ750MK Midnight Maxim (semi-restored DD)
                1977 XS650D ( patiently awaiting resto)

                Sometimes it takes a whole tank of gas before you can think straight.

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                • #9
                  Originally posted by Schming View Post
                  This one I made from an old float bowl gasket, for my '80G carbs:





                  ]
                  That caliper stood on end and set to .910(23mm) works too.....or.915 above 5,000ft. elevation.
                  81H Venturer1100 "The Bentley" (on steroids) 97 Yamaha YZ250(age reducer) 92 Honda ST1100 "Twisty"(touring rocket) Age is relative to the number of seconds counted 'airing' out an 85ft. table-top.

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