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Gas pissing out of air box, Save me please

Discussion in 'XJ Technical Chat' started by Khakis, Apr 17, 2021.

  1. Khakis

    Khakis New Member

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    All and any advice is appreciated

    Purchased a 1981 XJ 650 without knowing that it had a seized engine. So far I have honed out cylinders, replaced piston rings, put new jets in the carbs , replaced brakes etc... put gas in tank then turned the key for first time today. Engine turns over, which was a joy, however it won’t start. First thing I noticed was a constant stream of gas flowing out of a hose that’s connected to the bottom airbox.. I read a few other posts on here that mentioned the petcock and floats in the carbs. Just wanted to make sure I’m not missing any other key steps before trying to start her up again.

    thanks in advance
     
  2. XJ550H

    XJ550H Well-Known Member Premium Member

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    the needle valves in the carbs need to be replaced not stoppping the fuel when floats rise.
    second would be proper adjusting of the floats for proper fuel level in the bowls

    check oil for fuel and change it
     
  3. Toyobaru866

    Toyobaru866 Active Member

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    Not much to add, would have been my thoughts. Petcock vacuum not working so constant flow of gas, not good but not a direct problem if the rest is ok. At least one stuck float or a valve pin not closing properly on the valve seat. Others will now more.
     
  4. Toyobaru866

    Toyobaru866 Active Member

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    Didn't see XJ550H post first.
     
  5. XJ550H

    XJ550H Well-Known Member Premium Member

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    as far as the petcock goes even if left on prime the flaot system in the carbs will stop the fuel flow
     
  6. Khakis

    Khakis New Member

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    Ok sounds good, thanks
     
  7. XJ550H

    XJ550H Well-Known Member Premium Member

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  8. Marchy

    Marchy Member

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    Check throttle dial carbs are too open.....been there done that!!!....lol
     
  9. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    That won't cause fuel to overflow from the carbs. Not ever.
     
  10. Marchy

    Marchy Member

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    Happen to me after a bench sync that I left the butterflies way to open......or might have been a coincidence.
     
  11. Marchy

    Marchy Member

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    And to confirm I meant idle screw
     
  12. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    The only thing that keeps fuel from overflowing is the float needles. You probabaly had a stuck float and messing with the idle speed screw bumped things around enough for it to work properly again.
     
  13. Jerrod Robinson

    Jerrod Robinson Member

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    Don't know if you have solved this, but my 750 does that if my floats are sticking. I just tap the float bowls with a socket wrench and it stops. Only happens if I Clean the Carbs or something.
     

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