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Excessive Mag drop during Runup

in 912 / 914 Technical Questions 11 years ago

  • Re: Excessive Mag drop during Runup

    by » 11 years ago

    Hi Ron,

    What is your idle rpm after the engine is warm? Is your engine a 912 UL or a 912ULS? If the idle is set too high or too low starting will be an issue. If the plane has sat a long time and those carb sync gauges have a wide spread of 3" or more you may have a plugged idle jet. The one with the highest vacuum will have the clogged jet.

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

      
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  • Re: Excessive Mag drop during Runup

    by » 11 years ago

    Thank you Roger, and all who contributed to my "Excessive Mag Drop during Runup" post. I followed on with a subsequent hard starting problem after re-gapping the pugs per Roger's suggestion. With all your guidance I was able to solve both problems.

    After re-gapping the plugs, and re-yncronizing the plugs my excessive mag drop problem went away. I discovered that one of my "choke' cables was pulling more then on the carb on the side opposite. After re-adjustment the hard starting went away.

    Sorry for not thanking you all sooner. . . I was just plain gleeful that the problems were solved.

    --Ron
      
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  • Re: Excessive Mag drop during Runup

    by » 11 years ago

    Hi,

    I disconnected both carbs form their flanges and cleaned the bowls and jets with carb cleaner and applied pressure. After installing them again I have mag drops at 3600 rpm left and right of ca 500 rpm. Looks like the carbs are out of sync now. The weather is too bad to try check this.

    Please advice.

    Jan
      
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  • Re: Excessive Mag drop during Runup

    by » 11 years ago

    Jan,

    Check the posts subsequent to my original post ofthe same topic. I hadn't done any car cleaning, etc., but did re-gap my plugs, and re-syncronized the carburetors. My Mag drop problem went away after doing so.
      
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  • Re: Excessive Mag drop during Runup

    by » 11 years ago

    Ron,

    Yes if have read this thread and I think a re-synch of the carbs will do the trick.

    What puzzles me is that I have removed and installed the carbs with all the cables etc. in place. I needed only access to the bottom of the carbs.

    Did I upset the cables lengths such that the carbs went significantly out of synch?

    Jan
      
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