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Re: Thick Mist at carb mouth at higher revs.

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  • marshengnz
    Just for interest, I too have a clear float bowl and on WOT, if I turn off the fuel and watch the fuel level drop in the bowl, it only starts to splutter when
    Message 1 of 18 , Mar 11, 2012
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      Just for interest, I too have a clear float bowl and on WOT, if I turn off the fuel and watch the fuel level drop in the bowl, it only starts to splutter when there is next to nothing left, not before.

      This seems to indicate once again that I have a very rich mixture.

      The air bleed hole is 0.8 mm on the OKO. The original Honda carb (a 1980 one) although quite different on construction, has much the same emulsion tube drilling pattern and it has a 1.8 mm air hole.

      I'm talking myself into drilling a bigger air hole aren't I. I think a bigger main jet will compensate for a oversize air jet.

      Cheers Wallace
    • Caparo
      ... wallace, yes 0.8mm does appear to be a bit small the trick with 30mm & 28mm Mikuni s was to go to 2mm air jet on a 200cc barrel, I do not recall ever
      Message 2 of 18 , Mar 11, 2012
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        On Sunday 11 March 2012 08:24:15 marshengnz wrote:
        > Just for interest, I too have a clear float bowl and on WOT, if I turn off
        > the fuel and watch the fuel level drop in the bowl, it only starts to
        > splutter when there is next to nothing left, not before.
        >
        > This seems to indicate once again that I have a very rich mixture.
        >
        > The air bleed hole is 0.8 mm on the OKO. The original Honda carb (a 1980
        > one) although quite different on construction, has much the same emulsion
        > tube drilling pattern and it has a 1.8 mm air hole.
        >
        > I'm talking myself into drilling a bigger air hole aren't I. I think a
        > bigger main jet will compensate for a oversize air jet.
        >
        > Cheers Wallace
        wallace,
        yes 0.8mm does appear to be a bit small the trick with 30mm & 28mm Mikuni's
        was to go to 2mm air jet on a 200cc barrel, I do not recall ever changing
        air jet size on the 250Cc twins (ie 125 cc barrels ) and i do not remember
        what stock for the 28 or 30mm carbs were.(certainly smaller than 2.0)

        --
        TTFN
        Caparo.
      • djtcz2001
        original message ... snippety........ I get a nice thick mist at the carb mouth above 9500 through to 13000 ... The nominal airflow in a carb near open
        Message 3 of 18 , Mar 11, 2012
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          original message
          --- In mc-engine@yahoogroups.com, "marshengnz" <marshland@...> wrote:
          >
          snippety........ I get a nice thick mist at the carb mouth above 9500 through to 13000
          >
          > It has an emulsion tube and from what I have read, above 2/3 throttle, the holes in the tube lean the mixture off to ensure the correct balance. My guess is there is so much fuel being drawn out that it is not really vapourising well and floating all over the place...... =======================

          The nominal airflow in a carb near open throttle and high rpm is probably 100 mph or more. After sticking my head out the window at 60 mph my senses tell me there is not much drifting or floating going on in the upstream directiobn in a 100 mph gale, without some powerful wave action going on in the intake/engine/exhaust system.

          Partially closed throttles are good at reflecting/blocking waves.
        • Swiss
          Wallace, If you wanted to have some fun with it you could always drill and tap it to fit some small Mikuni air jets to it. They come in various sizes and that
          Message 4 of 18 , Mar 11, 2012
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            Wallace,

             

            If you wanted to have some fun with it you could always drill and tap it to fit some small Mikuni air jets to it.  They come in various sizes and that would allow you to actually tune it rather than just take a chance and try to tune it out with other jetting in the carb.

             

            Swiss

             

            From: mc-engine@yahoogroups.com [mailto:mc-engine@yahoogroups.com] On Behalf Of marshengnz
            Sent: Sunday, March 11, 2012 1:24 AM
            To: mc-engine@yahoogroups.com
            Subject: Re: Thick Mist at carb mouth at higher revs.

             

             

            Just for interest, I too have a clear float bowl and on WOT, if I turn off the fuel and watch the fuel level drop in the bowl, it only starts to splutter when there is next to nothing left, not before.

            This seems to indicate once again that I have a very rich mixture.

            The air bleed hole is 0.8 mm on the OKO. The original Honda carb (a 1980 one) although quite different on construction, has much the same emulsion tube drilling pattern and it has a 1.8 mm air hole.

            I'm talking myself into drilling a bigger air hole aren't I. I think a bigger main jet will compensate for a oversize air jet.

            Cheers Wallace

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