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MikesXS slider carbs leaking

Discussion in 'The Garage' started by cmills83, Mar 4, 2019.

  1. joeluvs2fish

    joeluvs2fish Bob to live!

    Had a similar problem after rebuilding carbs on my (don't be offended) '67' CB77. Everything worked fine until I put the bowls on. The bowl gasket was sticking out just enough to catch the float on the left carb. Just some more food for thought. Good luck!
  2. cmills83

    cmills83 XS650 Addict

    Cool thanks for all the feedback so far. So an update, I actually moved the 'tang' on the floats down a bit and the leaking seems to have stopped. Maybe this is just giving it some extra momentum so everything actually slides up into place to stop the flow of gas?

    But with this comes a new issue, now that carb seems to backfire/misfire when the bike is cold on that side. :shootme:. I guess I'll drain them and adjust it back up a bit
  3. 5twins

    5twins XS650 Guru Top Contributor

    Like I said, when you adjust that tang, you change the float height, and that changes the fuel level in the carb. Lower the fuel level too much and that carb will run lean, raise it too much and that carb will run rich and/or overflow/leak fuel. You should be measuring the float heights to see exactly what they're set at instead of mucking around in the dark using random unknown settings. I would measure the good carb and match the bad carb's float setting to that.
    solo2racr likes this.
  4. cmills83

    cmills83 XS650 Addict

    MIkes said 16mm, so is that just measured from the carb body to the bottom of the float?
  5. 5twins

    5twins XS650 Guru Top Contributor

    Usually, with the carbs turned upside down, from the carb body float bowl gasket surface (not the gasket) to the top of the rounded part of the float. Technically, that would be the bottom of the float once the carbs are turned right side up again. Here's some set at about 21mm .....

  6. cmills83

    cmills83 XS650 Addict

    Running out ideas here, tried 16mm as recommended by mikes and the carbs leaked right when I reassembled. Backed it off to 18mm and the bike seems ok, a bit lean at first start but rideable. I rode about 3 miles then they started leaking again, then another mile it stopped.
  7. Brassneck

    Brassneck XS650 Guru

    Sounds like a bad float valve or at least it's not sealing consistently....perhaps it's tilting or you have a bad float? Double check the float height per the above and see if it's consistent with where you set it to make sure it didn't change somehow. Maybe vibrations make it move around irregularly?

    One thing that I sometimes do is remove the bowl (with a floats hanging), attach a bit of hose to the fuel inlet and give a gentle blow....you should be able to blow air without issue...now raise the floats gently with a free hand, until it seals the float valve...at some point it should stop your air flow. If it doesn't stop it entirely, the valve is bad. You can also get a general idea on where the float is when it stops air flow to see if it's about where it should be...NO, it's not scientific/precise, but it does help a bit with perspective.
    TwoManyXS1Bs and gggGary like this.

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