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Cyl 2 perhaps not firing properly

Discussion in 'XJ Technical Chat' started by andrew15, Jul 13, 2015.

  1. andrew15

    andrew15 Member

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    I've been reading my plugs all season here and there just trying to get that ideal mixture but either way it's been running great.

    All 4 headers are hot as if they're firing but I've now bottomed out #2s mixture screw and the plug still comes out black.

    My guess is it's only fully firing at higher rpms since I do hear a change in sound and power in higher revs
     
    andrew15, Jul 13, 2015
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  2. k-moe

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

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    Don't bottom out the #2 idle mixture screw as that cylinder will be very lean (or not getting fuel at all) at idle.

    What sort of black is it? Sooty or does it have an oily sheen?

    Do you have acccess to a Gunson Colortune?


    What has been done to the machine so far? Carbs cleaned (including polishing the slides)? Valves in spec? Compression test done?
     
    Last edited: Jul 13, 2015
    k-moe, Jul 13, 2015
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  3. andrew15

    andrew15 Member

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    Just backed it out, naturally it's starting much easier now as well, durr that was dumb.

    It's sooty that's for sure, no colortune and I don't think I'll be buying one any time soon!

    I cleaned the carbs this winter, checked the valves and changed one of the shims and then balanced the carbs as best I could with the bottle method.

    Never have done a compression test though!
     
    andrew15, Jul 13, 2015
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  4. k-moe

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

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    Hmmm. Sooty, but the question is sooty when. I say get four new plugs and start doing plug chops for that cylinder. One at idle, and one at each transition thereafter. OR.....pull the tophat off of #2 and see if the slide might be stuck in an upward position. Also recheck your fuel height on that carb (wet check on the bike).
     
    k-moe, Jul 13, 2015
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