Home Forums Shifter Karts KZ Carb is always overflowing

This topic contains 8 replies, has 6 voices, and was last updated by  Thomas Barth 5 years, 11 months ago.

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  • #7321


    I have a problem with my carb, and I can’t seem to find the problem. Last week I had a race, and I spent almost all day to find the correct setup. One didn’t make the kart start at all, the other one started but stuttered  until i reached 10 000 rpm and couldn’t reach more than 13 500rpm.

    The last setup I did before the race was SPOT ON… but when I was racing, one of the racer I passed during the race told me that my Carb was overflowing like crazy from the 2 little vents on each side of my VHSB30 Carb. And i does it all the time, from stand still to WOT.

    Now, I have clean every passages in the carb before and made sure every part was clean before racing, so WHY is the fuel going out from there all the time?

    Can you explain and help me with this? Is my carb broken?

  • #7323

    Chris Beebe

    I would look into your needle and seat and your float operation.


  • #7379

    Thomas Barth



    How are your fuel pump hoses routed to carb?

  • #7423


    Sabastien, How are your fuel pump hoses routed to carb?

    <hr />

    <div class=”bbp-reply-signature”>tdb/GFK</div>

    Well, right now I have a Dellorto Square Pump. One inlet, one out toward the fuel filter and the carb, and one for the pulse…

    That engine used to have a Mikuni round pump on it with dual Outputs, so I guess on returns to the fuel tank.


  • #7424

    1) Are the vents routed up over the carb?
    2) Do you have a return line to the tank?
    3) Is the tank vented?
    4) Can you post pictures of your current setup?
    5) Why did you replace the round pump with the square one?

    Sounds like you don’t have a return to the tank…

  • #7426

    James McMahon

    <span style=”color: #444444; font-family: Arial, Helvetica, serif; font-size: 12px; line-height: 21px; background-color: #efefef;”>”1) Are the vents routed up over the carb?”</span>

    ^ This……
    There should be a tube going from the vents at the bowl to the top of the carb, otherwise it will spew fuel and that would be pretty normal.

  • #7604

    Thomas Barth

    My guess is that you need a return line between pump and carb back to tank.

  • #7653

    Brian Degulis

    If it’s doing it at a stand still it’s either your float level or your float needle and seat or possibly a punctured float. With the Dellorto pump you don’t use a return line. It’s possible that your old set up with the Mikini pump and return line was  covering up a carb problem you had all along.



  • #8342

    Thomas Barth



    Do you have a vent hose installed on the vent tubes. You can run a tube from one vent up and over carb top, down to other tube. Put breather slit in hose at top.

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