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B&S Updraft Carbs

Discussion in 'Mechanic and Repair' started by ArchZangel, Oct 18, 2007.

  1. ArchZangel

    ArchZangel LawnSite Member
    from Florida
    Messages: 24

    Hi my name is Mike. I have been a outdoor power equipment tech for awhile now. But one thing that still confounds me are the old updraft carbs from briggs. I need some advice from the other mechs out there. DO they ever not leak or flood? Do they all leak around the air horn cover?..Or have I just been unlucky? Even new one I have installed have this problem. Some where on generators, some were on chipper/shredders. I m glad they don't use this carb much anymore! Any advice would be apreciated!

  2. Bill Kapaun

    Bill Kapaun LawnSite Senior Member
    Messages: 963

    One of the reasons many of the OLD engines had updraft carbs was that they tended to. leak. Being an updraft, they didn't flood the cylinder, like a downdraft would.
  3. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029


    First off, If you order in a new carb and it floods right after install take it back off and order another.

    On older carbs I believe it's due to being mounted on that long intake, With the carb hanging off the bottom of it causes more vibration which causes excessive wear to the brass needle valve seat.

    I never go into one of these with a flooding problem without replacing the seat also and have never really had any problems with flooding afterwords.

    Another thing to check is the upper body for warp-age (where the top mounts to the bottom). Over tightening of the screws will warp the upper body and cause a non sealing situation, When running fuel will seep through the gasket.

    I have set the upper body up-side down and LIGHTLY tapped these mounting screw areas back downward to get the upper body to seal properly again.
  4. ArchZangel

    ArchZangel LawnSite Member
    from Florida
    Messages: 24

    Thanx! for the info man

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