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1985 xj700 runs on 2 cylinders

Discussion in 'XJ Technical Chat' started by jed mullee, Apr 28, 2015.

  1. jed mullee

    jed mullee New Member

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    Yes I do have have a maxim x. It has a radiator. It is not required to to move cam check valve clearances. I will get two new plugs and try that. I will also try the sea foam and see if I can some fire in the holes. I am a Harley mechanic by trade but kinda new to the 4 cylinder world. This machine has me thrown for a loop because all the basic needs of a engine are there. It makes no sense to me why it doesn't run right. Thanks for all your guys help.
     
    Last edited: May 7, 2015
  2. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

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    Typo, too early in the morning.... Was supposed to say ".... you must LIFT the cams in order to CHANGE them."

    Dave
     
  3. jed mullee

    jed mullee New Member

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    Lol. I understand how that works.
     
  4. jed mullee

    jed mullee New Member

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    OK guys a little up date. I switched the coils and wires around so the running cylinders were on the dead cylinders. It was firing on 3-4 cylinders and not firing on 1-2. Is it a pickup coil issue or a coil issue.
     
  5. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

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    Coils fire as 1/4, and 2/3.... Not sure of pickups---- I'll look in the book
     
  6. k-moe

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

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    Are we sure that the wires were on the correct cylinders in the first place?
    It would be a coil if the bad coil had been hooked up to 3 and 4 instead of 1 and 4.
     
  7. jed mullee

    jed mullee New Member

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    Yeah I'm sure they are in the right spot because 1-4 still have the factory tags on them. Is their a firing order to these motors. Because the plug that is tagged 4 is on cylinder 3.
     
  8. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

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    I don't have anything that tells what parts of the pickups go to what coils.

    So, if 1/2 fire, theoretically both coils are good. BUT, if someone didnt hook them up correctly, then we would see this happen if one coil is bad.

    Check your coils and make sure that one coil is connected to plug .1 and 4, not 1 and 2. The other will be 2 and 3..... Then just make to have the correct lead going to the correct coil. Hopefully , that will be the first part of the issue. Zz which allow you then diagnose the second part- which is to simply determine what coil needs to be replaced. Hopefully not needing to farther up stream to the pickup.....

    Dave F
     
  9. k-moe

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

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    Both cylinders on a given coil get spark at the same time. One cylinder gets spark on the compression stroke, the other one on exhaust.

    Left coil, Orange lead wire, cylinders #1 and #4
    Right coil, Gray lead wire, cylinders #2 and #3

    The cylinders are numbered sequentially from left to right, beginning with #1 on the left.

    Having the #4 and #3 plug wires swapped will cause both #4 and #3 to get spark at the wrong time.


    And that's what I get for making assumptions. You said good spark on both 3 and 4. I didn't even think to ask you to check which plug wires you had on which cylinders.
     
    Last edited: May 8, 2015
  10. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

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    It might also cause 2 to get a spark at the wrong time if that wasnt the correct lead either.....
     
  11. jed mullee

    jed mullee New Member

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    UPDATE. The bike runs like a watch now. I feel like a complete idiot also. The plug wires for 3-4 were in the wrong spot.
     
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  12. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

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    Naaah, you were smart enough to come here and ask us. That's why we're here.

    Glad we could get you straightened out
    :D
     
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  13. jed mullee

    jed mullee New Member

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    I appericate all the help. The funny thing about bike is the guy I got it from said it was fast a hell. I'm 100% positive that it had to be running on only 2 cylinders for a long time.
     
  14. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

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    Very likely he didn't even know----- yeah, when the X is dialed in..... Whew, hang on tight:)
     

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