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ROUGH IDLE AND NO POWER

Discussion in 'XJ Technical Chat' started by HeckticHaze, Jul 25, 2015.

  1. HeckticHaze

    HeckticHaze Member

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    I have an 1982 XJ750RJ. It has about 15k miles. The bike was running smoothly but it had no power. I performed a compression check and valve clearance check. Both were fine. I remembered to unplug the TCI when doing the compression check. After I put the bike back together the idle is very rough. I checked and I have spark on all 4 cylinders. All four plugs are looking rich. My choke system is not engaged. The carbs have been completely torn down two years ago and rebuilt. No air leaks. What could have changed so drastically? Any information would be appreciated.
     
    HeckticHaze, Jul 25, 2015
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  2. fiveofakind

    fiveofakind Well-Known Member

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    have you wet-set the float levels, bench sync the carb, vacuum sync the carbs, & colortuned the plugs......????
     
    fiveofakind, Jul 25, 2015
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  3. HeckticHaze

    HeckticHaze Member

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    After I rebuilt the carbs two years ago I did everything you have listed. Bike ran good. Just within the last month it has had a reduction in power. Roll the throttle and it will go but no quickly. Can't explain it. Now since I put the valve cover back on and did the compression checks it is running very rough.
     
    HeckticHaze, Jul 25, 2015
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  4. fiveofakind

    fiveofakind Well-Known Member

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    have you vac-sync & colortune lately....or 2 yrs ago.......you may want to do those 2 things again....
     
    fiveofakind, Jul 25, 2015
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  5. HeckticHaze

    HeckticHaze Member

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    2 years ago. I am just concerned it changed so quickly after my tests. I will resync and colortune again. See if that helps.
     
    HeckticHaze, Jul 25, 2015
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  6. k-moe

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

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    It is possible for the idle air screws to back their way out if the o-rings have perished, or if the threads in the carb bodies are worn excessively.

    It is also possible that the slides are sticking, or that the enrichment plungers are not sealing. Press down on the enrichment plungers with your finger and see if they move.
     
    k-moe, Jul 25, 2015
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