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I have a 912ul fitted to a Reality escapade, the carbs have been balanced with a manometer,even when the engine is hot, if I come back below 2000 rpm then engine will stop particulary on roll out.
at 4800 rpm in flight it sometimes misfires,when it stops (still hot) it needs full choke to start it. the needles are set two notches from the top, and the plugs are more white than choclate brown
it seems to me it is running too lean could this be float level or needle position?
The engine only has 70 hrs from new, but was previously removed from a damaged flexwing and totally stripped and overhauled by a reputable company.
  • Re: 912UL poor idle below 2000 rpm

    by » 11 years ago


    Hi Malcolm,

    Could be the jet needle position. The standard Rotax setup is three notches from the top, making the mixture richer. You might also check the idle mixture screw. Standard setting there is the screw turned out 1.5 turns.

    Bill.

  • Re: 912UL poor idle below 2000 rpm

    by » 11 years ago


    Thanks Bill I get the same problem with the idle jet set to 1.5 turns and was reccomended to try 2 turns out. Have been considering altering the needle position, will try that next.
    Have just Emailed Conair to see what ideas Conrad has.
    Thanks again
    Malcolm

  • Re: 912UL poor idle below 2000 rpm

    by » 11 years ago


    Malcolm,

    Sounds more and more like a needle problem with the white plugs. You've probably already checked this, but if a diaphragm has a leak in it, the venturi vacuum wont pull the needle up as far a it should. There also is a small tab on the edge of the diaphragm that fits in a notch in the carb body. Sometimes these are installed out of position and can also cause an air leak. If the plugs are white on both sides of the engine, I'd bet on the needle settings.

    Bill.

    Thank you said by:

  • Re: 912UL poor idle below 2000 rpm

    by » 11 years ago


    Maybe the reputable company may have made a mistake? It is running lean. Leave the idle screw set to 1.5 turns as that isn't your problem. Do set the needle clip back to the 3rd notch from the top as Bill suggested. If changing the needle to the third notch doesn't fix the problem then those carbs need to come apart and be checked. It is something they did to the carbs. They may have done a couple of things wrong. My bet is something isn't right inside the carb. Have3 someone with experience with these carbs take a good look inside.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell


  • Re: 912UL poor idle below 2000 rpm

    by » 11 years ago


    Thanks for your help, it turned out to be dirt in the carb after all, now runs nicely

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