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High revving

Discussion in 'XJ Technical Chat' started by stew, Apr 9, 2016.

  1. stew

    stew Member

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    Hi lads I started a thread about my xj750 revving high you guys suggested replacing the gaskets on the boots between the carbs and engine this seems to have done the trick with no more sticking or over revving,happy days!
    It is now running lumpy,I think it's firing on all cylinders but it sounds all over the place do I now try this colortune thing,never done it before is it simple enough to do?
     
    stew, Apr 9, 2016
    #1
  2. k-moe

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

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    A lumpy idle can be because of uneven fuel mixtures, but that can be from multiple causes.

    Valve clearances must be in spec.
    Float levels must be in spec.
    Idle mixture must be correct (check with a color tune, via reading your plugs, or via the idle drop method).
    Throttle plates must be synchronized (a bench synck gets the plate close; a runnign synch gets them exact).

    Of the above, which has already been done?
     
    k-moe, Apr 9, 2016
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  3. stew

    stew Member

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    None! Haha
    Which one should I start with?
     
    stew, Apr 9, 2016
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  4. k-moe

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

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    k-moe, Apr 9, 2016
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  5. stew

    stew Member

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    I've read it but like it said in the title it's definitely overload especially for my tiny brain.
    I could do with printing it out so I can chill with it and refer back to it as I go.
     
    stew, Apr 10, 2016
    #5
  6. rocs82650

    rocs82650 Well-Known Member

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    Welcome aboard. No worries...the "overload" will start to sort itself as you wrench along.

    Gary H.
     
    rocs82650, Apr 10, 2016
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  7. stew

    stew Member

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    The 4th from the left cylinder has a ticking sound which goes away when spark plug cap is removed.
    Would that be anything to do with the valve shims?
     
    stew, Apr 10, 2016
    #7
  8. k-moe

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

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    Seems to me that you may be hearing the spark jump to the head instead of through the electrode of the plug. Try swapping plugs around and see if the tick follows the plug. THen try swapping #1 and #4 plug wires to see if the tick follows the wire position.

    There should be valve noise when they are adjusted properly, but it won't go away when you remove a plug wire.

    There may be a tick from the cam due to slightly large endplay clearance at the rightmost cam bearing cap. This is a known issue that does not cause any damage to the engine. Yamaha did a TSB about it, and said as much. Again, it won't go away when you remove a plug wire.
     
    k-moe, Apr 10, 2016
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    DrewUth and stew like this.
  9. stew

    stew Member

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    Cheers pal i will try that tomorrow after work.
     
    stew, Apr 10, 2016
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  10. stew

    stew Member

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    Tried your suggestions tick still there just on 4 even with a new spark plug.
    Would it have anything to do with the exhaust if not sealing properly?
     
    stew, Apr 11, 2016
    #10
  11. rocs82650

    rocs82650 Well-Known Member

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    Two of the ht caps have a screw in holder for the resistor. Disconnect the battery and make sure they're seated.

    Gary H.
     
    rocs82650, Apr 11, 2016
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  12. k-moe

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

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    Could you make a video so I can hear the tick? I think that it's probably just the cam endplay, and therefore nothing to worry about.
     
    k-moe, Apr 11, 2016
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  13. k-moe

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

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    All four on the 750. So many little details that vary....annoying, and difficult to remember them all.
     
    k-moe, Apr 11, 2016
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  14. rocs82650

    rocs82650 Well-Known Member

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    Thanks for the correction. I don't reply to a lot of threads because of this. You help a lot of members k.

    Gary H.
     
    Last edited: Apr 11, 2016
    rocs82650, Apr 11, 2016
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  15. k-moe

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

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    Oh, don't let that stop you from replying. Being wrong is almost half of what I do ;)
     
    k-moe, Apr 11, 2016
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  16. rocs82650

    rocs82650 Well-Known Member

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    Lol.

    Gary H.
     
    rocs82650, Apr 11, 2016
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  17. stew

    stew Member

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    Any help wrong(or right) is welcome lads. Haha
    I will try and make a video of it.
    Would the exhaust cause noise like this?
    What plugs and caps do you guys use?
     
    stew, Apr 12, 2016
    #17
  18. XJ550H

    XJ550H Well-Known Member Premium Member

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    NGK stock plugs and caps
     
    XJ550H, Apr 12, 2016
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  19. stew

    stew Member

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    This is what I'm using bought as an xj750 1982 -84 set is this what you have?

    2 X XB05F-R NGK PLUG CAP

    2 X LB05F-R NGK PLUG CAP

    4 X BPR7ES NGK SPARK PLUG
     
    stew, Apr 13, 2016
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  20. stew

    stew Member

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    2 X XB05F-R NGK PLUG CAP

    2 X LB05F-R NGK PLUG CAP

    4 X BPR7ES NGK SPARK PLUG

    This is what I have sold to me as xj750 set. Is this right?
     
    stew, Apr 13, 2016
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  21. stew

    stew Member

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    2 X XB05F-R NGK PLUG CAP

    2 X LB05F-R NGK PLUG CAP

    4 X BPR7ES NGK SPARK PLUG

    Are these right I bought of eBay as an xj750 1982 - 84 set.
     
    stew, Apr 13, 2016
    #21
  22. k-moe

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

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    NGK BP7ES in all four holes. The plug caps have resistors in them, so you don't need, or want, resistor plugs.
     
    k-moe, Apr 13, 2016
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  23. stew

    stew Member

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    Hi lads this is a video with the ticking sound??
     
    stew, Apr 17, 2016
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  24. stew

    stew Member

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    Sorry boys can't seem to upload a video tried 3 times and I can't see it in the thread.
     
    stew, Apr 17, 2016
    #24
  25. k-moe

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

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    Are you using a hosting site? Which one?
     
    k-moe, Apr 17, 2016
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  26. stew

    stew Member

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    Just on my phone, don't know about a hosting site? the file is an mp4
    Are you guys on facebook as it uploaded there no problem.
     
    stew, Apr 17, 2016
    #26
  27. k-moe

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

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    I am, and commented. You can't directly upload files here without a premium membership, and then I think it's just pgotos in your gallery that can be uploaded. I use Photobucket to host most of my photos, and youtube for my videos.
    You can link your Facebook post here, but those without Facebook accounts probably won't be able to view it.
     
    k-moe, Apr 17, 2016
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  28. rocs82650

    rocs82650 Well-Known Member

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    I can also upload a pic just taken with my phone.

    Gary H.
     
    rocs82650, Apr 17, 2016
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