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Firing Order

Discussion in 'XJ Technical Chat' started by KrS14, Sep 3, 2011.

  1. KrS14

    KrS14 Active Member

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    Just a quick question to anyone that has taken notice to what the actual firing order is on our bikes. I forgot to check when i had the valve cover off last :/

    Is it: 1-2-4-3?

    Thanx guys!
     
    KrS14, Sep 3, 2011
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  2. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    It kinda doesn't matter so much.

    These bikes have a "wasted spark" system; each coil (1-4 and 2-3) fires both its plugs every time it fires.

    But since only one cylinder of each pair will be on its compression stroke at that time, only that one "matters" while the other cylinder is firing on its exhaust stroke (the "wasted spark.") You can mix up the 1/4 or 2/3 plug leads and it wouldn't matter.

    So the "order" is like 1/4 (take your pick) 2/3 (take your pick.)
     
    bigfitz52, Sep 3, 2011
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  3. Militant_Buddhist

    Militant_Buddhist Member

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    what Fitz said. I just think of it as one pickup coil on the end of the crank signaling one coil for a pair of cylinders (call 'em the up ones) and the pickup 180 degrees away signalling the other (bottom) pair. All that matters for whether or not they fire is cams opening and closing the appropriate valves.
    What I mean is, for that part of the ignition system I hardly concern myself with the numbers. It's just "inboard cyclinders from the grey wired coil, outboard from the candy-cane one" ya know?
     
    Militant_Buddhist, Sep 3, 2011
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  4. KrS14

    KrS14 Active Member

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    Ya I understand it's wasted spark, but I need to actually know the proper order.

    The difference between:
    1-2-4-3 and 2-1-3-4
    Makes a huge difference in what i'm investigating.

    It would HAVE to be one of those two correct?
    1-4 and 2-3 can't fire consecutively.
     
    KrS14, Sep 3, 2011
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  5. KrS14

    KrS14 Active Member

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    Maybe i asked the wrong question. What i need to know, is what is the power stroke order. :)
     
    KrS14, Sep 3, 2011
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  6. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    Golly. It's probably 1,3,4,2 but it could be 1,2,4,3, I guess.

    Take the valve cover off, and rotate the motor, stopping at the "T" mark each revolution and see whose valves are both closed.

    Let us know if you would; I'm curious now.
     
    bigfitz52, Sep 4, 2011
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  7. KrS14

    KrS14 Active Member

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    Guess i'm checking my valve clearances while i'm in there :) I'll repost back after i find out.
     
    KrS14, Sep 4, 2011
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  8. KrS14

    KrS14 Active Member

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    Power stroke order is:

    1-2-4-3

    Clearances haven't moved ;)

    Hopefully this is helpful to someone in the future.
     
    KrS14, Sep 4, 2011
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  9. tskaz

    tskaz Active Member

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    Just out of pure curiosity...what exactly are you investigating?
     
    tskaz, Sep 4, 2011
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  10. KrS14

    KrS14 Active Member

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    Was looking into the balance of carb sync vs choke on cold startup, and needed to know if 12 or 34 fired consecutively.
     
    KrS14, Sep 4, 2011
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