Flloat Height (again, sorry!)
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Thread: Flloat Height (again, sorry!)

  1. #1
    Junior Member Dogwheel's Avatar
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    Flloat Height (again, sorry!)

    Hi, I've searched the forum and can't really find an answer---
    My bike is a '72 CL350 K4 with Keihan 722A (KB) Carbs, with round brass floats.
    Does anyone know the correct float height (measured with the Carb Bodies held inverted)?

    Seems it could be 19mm, 22mm or 26mm!

    At present they are set on 22mm, it runs OK, if a bit flat, and needs hardly any choke to start on a cold morning--by UK standards!

    Advice much appreciated.

    Robin.

  2. #2
    Super Moderator J-T's Avatar
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    I suspect you do not have the factory service manual. I know there are varied versions of your bike/carbs, there may be different specs as well. I've sent you a PM regarding the manual, likely one of the 350 experts will be along with more specific guidance.
    JT
    81 CM400T

  3. #3
    Junior Member Dogwheel's Avatar
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    That looks to be just what I need, thank you very much.
    Robin.

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  5. #4
    Senior Member Boomer343's Avatar
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    26 mm is factory spec.

    Based on modern, lighter fuel I now run 27 to 27.5 mm.

  6. #5
    Junior Member Dogwheel's Avatar
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    Thanks for that Boomer, I'm still wading through Tech Manuals, but I'm inclined to try your recommendation.

    Robin.

  7. #6
    Senior Member 83XLX's Avatar
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    The Honda factory shop manual doesn't give the float heights or much else for the carbs. There's a Honda carb manual with all that in it. That said, it's 26mm, but mine runs much better with them set to 27.5mm.
    1969 Honda CL350
    1983 H-D XLX-61 Sportster

  8. #7
    Junior Member Dogwheel's Avatar
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    Hi, I've just come indoors out of the cold garage, where I had carefully set my Float Heights to 27mm, rebuilt the carbs on the bench and checked for fuel flow via my test tank--zilch! removed the float bowls which were clean and dry!!
    It seems that at 27mm the float bowls impinge(good word?)on the floats and close the needle valves, preventing any fuel flow.
    Tomorrow I'll revert to 22mm and see how that works.
    I'm guessing that Honda and Keihin conspired to keep us awake nights by changing carb specs willy nilly!
    Will report back.
    Robin.
    Last edited by Dogwheel; 12-02-2019 at 10:34 AM. Reason: muddled tense

  9. #8
    Senior Member Boomer343's Avatar
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    Dogwheel either your method for setting the float height is incorrect or the parts you are using are wrong. You are too far off spec and going in a different direction than what the rest of us have found to work.

    I have never had a set of these carbs not function at 26 mm and the last 4 sets I did have been set to 27mm without issue. Two rebuilds were done with OE Honda parts and two were done with aftermarket kits. All have no issues with allowing fuel into the float bowl and then stopping the fuel flow.

  10. #9
    Junior Member Dogwheel's Avatar
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    Boomer, Would you please briefly outline the method you use to measure float height, I guess it's colder in your Alberta garage than mine in Worcestershire UK!
    Robin.

  11. #10
    Senior Member 83XLX's Avatar
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    The bottom of the float should measure 26 mm (or 27.5 mm) from the float bowl mating surface when the float tang just touches the pin on the bottom of the float valve. Make sure to hold the carb vertical (or close to it) before tilting it, and make sure the float valve is seated all the way when you take the measurement.

    Flloat Height (again, sorry!)-carbs-17-jpg.jpg
    1969 Honda CL350
    1983 H-D XLX-61 Sportster

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