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81 XJ-550 Wont Start

Discussion in 'XJ Technical Chat' started by Steve Blanchet, Nov 2, 2020.

  1. Steve Blanchet

    Steve Blanchet New Member

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    I'm baffeled, I have cleaned the carb's to no end, I've tip cleaned every hole in those carb's, New Gasket's, I know the carb's are good.
    The Valve shim's are all in spec, I have spark on all 4 , Thing is when i try to start it, it starts but shut off right away, wont stay running.
    Anyone have any clue's ? I've set the floats and bench synced the carb's.
    Compression is good .
    Please help.
     
  2. a100man

    a100man Well-Known Member

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    The pilot circuit in the carbs is often the problem. Does it run any better on choke? When you've cleaned the pilot circuit properly you should be able to squirt cleaner
    through until it comes out of the tiny holes in the roof of the carb by the butterfly - hitting you squarely in the eye.
     
  3. Steve Blanchet

    Steve Blanchet New Member

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    No,it does the same thing with the choke on, want's to start but thats it.
     
  4. Simmy

    Simmy Well-Known Member

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    Not doubting your rebuild but how are you certain of this?
    Did you follow the church of clean procedures found on this site?
    When you bench synced the carbs did you set them all with the butterfly slightly cracked open?
    Are you starting it with the tank in place? If so is the petcock set to prime? If set to on is the vacuum line attached and in good condition?
    Did you wet set the fuel levels?
     
  5. k-moe

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

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    The enrichmnet jets are in the bottom of the float bowls, and are often clogged.
     
  6. Minimutly

    Minimutly Well-Known Member

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    Plus one - these are tiny, and would explain the symptoms...
    They take some doing to clear....
     
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  7. XJ550H

    XJ550H Well-Known Member Premium Member

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    have you tried starter fluid?
    a quick shot in the air box will run the bike for about 10 seconds
    only do it once as too many tries will foul the plugs
     
  8. Steve Blanchet

    Steve Blanchet New Member

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    I used tip cleaners on them with carb cleaner
     
  9. k-moe

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

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    Did you confirm that they are clear by spraying carb cleaner directly into them, and watching the result (without your eyes in the way)?
     
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  10. a100man

    a100man Well-Known Member

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    What does 'tip cleaned' mean? Most folk are suggesting that either or both the choke(enrichmenst) and pilot circuts are dirty. If you are resisting taking the carbs off because you think you already cleaned them well enough please don't. Do as we suggest and ensure you get streams of fluid flowing through from those biddy little holes.
     
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  11. Steve Blanchet

    Steve Blanchet New Member

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    Tip clean as in A tip cleaner for a torch, i will take them apart again, clean them again ensuring i have fluid coming out every little hole there is in that carb body, thanks for the help, once i have every thing back together i will repost my finding's.
    I also noticed yesterday while pissing around, my Intake boot's have cracks in them, can barely see them but i ordered new one's anyways. Hope this works.
     
  12. k-moe

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

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    Hold off on changing the intake boots. Just because the cracks are visible does not mean that they are deep enough to cause a vacuum leak.
    Slowly and methodically spray carb cleaner around each boot with the engine warm and idling. If the engine speed increases you've found a leak.
     
  13. Yammaat

    Yammaat Active Member

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    Catch 22? ;-)
     
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  14. Huntchuks

    Huntchuks Well-Known Member

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    Clean carbs/get running/check boots.
     
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  15. XJ550H

    XJ550H Well-Known Member Premium Member

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    2 things are being talked about.
    the brass tube for the enrichment circuit and the carb bowl well where the brass tube goes and sucks fuel out of the bowl through the tiny hole on the bottom.
    did you clean out the well in the bowl from both sides? this is where you get sprayed in the face when you test them. carb cleaner will shoot across the room.
     
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  16. Steve Blanchet

    Steve Blanchet New Member

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    I got her running, having a bit of a problem with High rev's now, not sure what's going on ? Need to do some more trouble shooting.
     
  17. a100man

    a100man Well-Known Member

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    Good work - check you haven't got the throttle cable hitched up on the captive guide part at the carb end - done that a few times.
     
  18. Huntchuks

    Huntchuks Well-Known Member

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    Now is the time to checks boots for vacuum leaks. Leaks can cause the RPM's to rev high.
     
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