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rough Running 912 midrange rpm

in 912 / 914 Technical Questions 8 years ago

  • Re: rough Running 912 midrange rpm

    by » 8 years ago

    Yes I have moved the clips down on both carbs to the last notch on the needle.I believe there are 3 notches??
      
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  • Re: rough Running 912 midrange rpm

    by » 8 years ago

    4 notches.

    What elevation do you fly out of and what is your average altitude. This will help you decide on carb needle position. For most people leaving it in the factory position in the #3 notch is best, but there are a few people with special needs, but darn few.
    If you moved it down from #3 to #4 you richened the fuel. It is possible you went the wrong way. What are your EGT temps at your cruise rpms? Since we are talking about mixture and running setups, what are your plugs gapped at? Should be between .023 & .027. Narrow gaps for colder winter flying and wider gaps for hot summer flying.

    If in cold weather you are too rich with wide plug gaps it may cause you poor running with some vibration at a specific rpm.

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

      
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  • Re: rough Running 912 midrange rpm

    by » 8 years ago

    I am at 400ft asl. I am 100% sure that the clips were moved down on the needle.I have not checked the gap on the plugs but will do so. I am also very confident that its running a little lean as the plugs are more white than lite tan in color. Also in flight at midrange rpm if the choke is slowly engaged the eng smooths out somewhat.
      
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  • Re: rough Running 912 midrange rpm

    by » 8 years ago

    Has anyone ever had the carbs off and worked on them? If they haven't maybe someone should take a look with an experienced eye and if they have maybe someone didn't put them back together properly.


    Make sure the mixture screw on the bottom of the carb is turned out 1.5 turns. Then you may want to clean the idle jets inside the carb if it is running rough at idle. rpms at 4200-4900 are certainly not in the idle circuit range. Make sure the choke shaft center punch mark on the of the shaft is pointing at the pipe like protrusion coming out of the choke body. Maybe you have an air leak which would cause a lean condition and rough running.

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

      
    Report

  • Re: rough Running 912 midrange rpm

    by » 8 years ago

    Check this out. Italians have a solution to cure rough running and carb balance.

    http://www.flygas.it/index.php?option=com_zoo&task=item&item_id=9&Itemid=103

    Replace balance tube with large pipe to even up carb mixture.
      
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