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Bike runs great above 2K, surges at idle, eventually dies

Discussion in 'XJ Technical Chat' started by tichuang, Nov 13, 2006.

  1. tichuang

    tichuang New Member

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    Location:
    San Jose
    Symptom:
    At idle, if I don't adjust the idle speed to 1750+ rpms, the engine will sound like its struggling to stay alive and it will eventaully die out.

    Basically I trust this bike going long distances at highway speeds (which I do), but I don't trust it coming to a stoplight and idling.

    What I've done:
    Cleaned out the carbs, especially the pilot jets/passages. They are VERY clean.
    Checked coils for resistance, they are good
    Recut the wires and screwed on caps again
    Resynced the carbs. Runs a LOT better (since they were way off) but still dies.
    New petcock (manual not vacuum), so fuel supply is solid.

    What I suspect:
    The spark plugs are ashy from previously runnign rich, and one hadn't been firing for a while due to bad connections. Poor spark? (The bike pulls HARD at higher speeds, however)

    Float levels.. if these are off, could that cause a dying/surging idle?

    Pilot mixture screws.. I have these at 2 full 360° turns out. I don't have a colortune..

    Thanks in advance for your help guys
     
    tichuang, Nov 13, 2006
    #1
  2. BlueMaxim

    BlueMaxim Active Member

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    Standard setting for tuning the mixture screws after a cleaning is 2.5 turns out. Your engine needs more fuel to keep running is my first guess. Go 2.5 and see if things improve. Then find someone on this forum who can help you colortune! I suspect one session with a colortune will have you grinning!
     
    BlueMaxim, Nov 13, 2006
    #2
  3. tichuang

    tichuang New Member

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    Re: Bike runs great above 2K, surges at idle, eventually die

    I used to have it at 2.5 turns out, but it was still dying then and it smelled a little rich.. I guess I'll turn it out to that anyways since that seems to be the standard. If I could get my hands on a colortune that would be awesome..
     
    tichuang, Nov 13, 2006
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  4. tichuang

    tichuang New Member

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    Re: Bike runs great above 2K, surges at idle, eventually die

    Should I try turning the screws out another turn or so more than 2.5 and see if it'll keep steady?
     
    tichuang, Nov 13, 2006
    #4
  5. BlueMaxim

    BlueMaxim Active Member

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    Couldn't hurt at all. This is a trial and error attempt at tuning. Search on this forum for Rickcomatic's old school tuning method. That will help you quite a lot.
     
    BlueMaxim, Nov 13, 2006
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  6. tichuang

    tichuang New Member

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    Re: Bike runs great above 2K, surges at idle, eventually die

    rick's write-up's are great. thanks for the info blue
     
    tichuang, Nov 15, 2006
    #6

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