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Carb Synch doesn't hold thru RPM range

in 912 / 914 Technical Questions 12 years ago

  • Re: Carb Synch doesn't hold thru RPM range

    by » 12 years ago

    Hi Mark,

    Not my plane. I use 1.2mm cable as all the Flight Design aircraft use and it moves like glass. The problems I see are with the home builds and the companies that use the Vernier cable systems. They are thick cables In a metal sheath. I prefer the teflon lined sheath. Then too many put too sharp a bend in the cable system. Unless I want to rebuild their whole system you get stuck with a cab sync that will never be perfect which drives me crazy.

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

      
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  • Re: Carb Synch doesn't hold thru RPM range

    by » 12 years ago

    I replaced the throttle cable and the carbs stay synched from idle thru 3700. Very nice. Using gauges again. However it is hard to start!!!!! Never had this problem before. Carbs and starting carbs rebuilt, everything seems fine, but will not start with starting carbs. After many tries I can get it to start using the throttle cable but it is beating the hell out of the equipment. Once it is warm it starts immediately. Not sure what to do next.

    Thanks for all the input, it was certainly enlightening.
      
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  • Re: Carb Synch doesn't hold thru RPM range

    by » 12 years ago

    Hi Robert,

    A couple of things that can hinder your starts even after the carb sync.
    If the idle is set too high
    If the idle is set too low
    If you give it throttle and your using the choke. A tad of throttle for a low idle set would help, but be a hinderence if the throttle is advanced too much especially combined with a high rpm for idle.
    If the richer circuit was put back in backwards.

    What did you set the idle rpm at?
    Are you using any throttle on first start?
    Double check the enricher stem and make sure the punch mark is facing the correct direction.

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

      
    Report

  • Re: Carb Synch doesn't hold thru RPM range

    by » 12 years ago

    Hi Roger
    Idle set at 1900. No throttle on initial start try. After a few tries turned off the choke and used the throttle.

    Will check the punch marks again. I checked them twice when I assembled the carbs.

    Thanks for your help Roger.

    Bob
      
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  • Re: Carb Synch doesn't hold thru RPM range

    by » 12 years ago

    Humor me and try reducing the idle setting to 1750 and then try your starts with the enricher.

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

    Thank you said by: Robert Hirschfield
      
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