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'85 XJ700X No fire on two cylinders

Discussion in 'XJ Technical Chat' started by Gravityisnotmyfriend, Oct 6, 2015.

  1. Gravityisnotmyfriend

    Gravityisnotmyfriend New Member

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    Location:
    Kg*m/S^2, Iowa
    I'm helping a buddy get his bike back on the road after it has sat for a couple of years. We pulled the carb bank and cleaned out all the carbs. They were in pretty good shape. But the CV slides were sticky. All the jets were cleaned and the slides moving like they should when we put them back together. All the diaphragms were in good shape as well.

    It's got spark on all 4 cylinders. All 4 carbs have gas in their float bowls. We got it started on ether, but it would only run on 1 and 3.

    What else could it be? Anything common on these bikes?

    I've started a thread over at ADVrider.com and will probably end up taking the carbs back off. It was suggested that the pilot and enrichment circuits could also be clogged causing issues. It seems to me it should still fire on ether even if those circuit were clogged - but we want this bike running right, so we'll go ahead and dig back in to them.

    Any other advice on what to check would be appreciated.
     
    Gravityisnotmyfriend, Oct 6, 2015
    #1
  2. Gravityisnotmyfriend

    Gravityisnotmyfriend New Member

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    After a search, looks like I got some reading to do!

    look under plug chops for an explanation of how the 3 circuits work and when in the carbs
    http://www.xjbikes.com/forums/threads/talkin-tech-various-thoughts-on-various-issues.14608/

    the church of clean Must reading
    http://www.xjbikes.com/forums/threads/in-the-church-of-clean.14692/

    naked carbs for understanding the circuits in photos
    http://www.xj4ever.com/inside your carbs.pdf

    and secret life of carbs
    http://www.xjbikes.com/forums/threads/the-secret-life-of-carburetors.14751/
     
    Gravityisnotmyfriend, Oct 6, 2015
    #2
    micheal wade likes this.
  3. quebecois59

    quebecois59 Well-Known Member

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    You have a pretty good start with these readings
     
    quebecois59, Oct 6, 2015
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  4. k-moe

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

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    Welcome aboard!
     
    k-moe, Oct 6, 2015
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  5. k-moe

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

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    There is one thing that I think we covered on ADVRider, but I want to be sure of for clarity here.

    Have you swapped the spark plugs around to be sure that all four are firing under compression? If the misfire follows the plugs then it's the plugs that are causing the problem.
     
    k-moe, Oct 7, 2015
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    rocs82650 likes this.
  6. CalilforniaBob

    CalilforniaBob New Member

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    CalilforniaBob, Nov 8, 2015
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  7. rocs82650

    rocs82650 Well-Known Member

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    Ditto.

    Gary H.
     
    rocs82650, Nov 8, 2015
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  8. XJ550H

    XJ550H Well-Known Member Premium Member

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    the photos do show some info
    Other Mikuni models, like this BS33 from a Maxim-X, move the pilot air jet from under the diaphragm to a passage located in the left side of the carb throat.
    nice little video on the cv carb



    cv carb tuning
    http://www.zrxoa.org/webpages/techinfo/carb/carbtuning.html
     
    Last edited: Nov 8, 2015
    XJ550H, Nov 8, 2015
    #8

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