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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 » 11 years ago

    I will be out of town until next Tuesday but will do that as soon as I get home and let you know how I made out. Thanks !!!!!
      
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  • Re: Carb Synch doesn't hold thru RPM range

    by » 11 years ago

    Roger,
    I first set the idle manually by backing the screws off completely (.004 clearance) then turning in 1 and 1/2 turns (which brought them back pretty much to where they were). Would not start - violent kickbacks. I took the throttle cables off to make sure they were not holding the carbs off idle. Would not start. No option to crack the throttle to assist. In total frustration I took the carbs back off to check them out again. The engine runs beautifully and starts beautifully AFTER it starts once. It is just the first start - and it almost sounds like a timing issue with the violent kickbacks. I read your post on the high torque starters, my engine was manufactured in 2005, serial 5.644.514, would it have that starter on it? I already have the soft start module and am ready to pull that back off. Wow this is frustrating - this engine has always been a good starter and an excellent operating unit.
      
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  • Re: Carb Synch doesn't hold thru RPM range

    by » 11 years ago

    Hi Robert

    It sounds like you have the dreaded sprag clutch failure. I am presuming you have a slipper clutch fitted.

    There is a very fine spring on the circumference of the sprag that becomes distorted when the engine kicks back. Every kick back seems to damage the spring more until it can be impossible to start.

    The fix is easy, just expensive. You need to fit a new sprag clutch, two soft start ignition modules and the new type flywheel. You should also service your gearbox and set friction torque as high as is recommended (800Nm/590ft/lbs)

    You need the large, gold coloured starter motor and make sure you have a good battery and leads. If the starter is black it is the smaller one that is not recommended on the 912s.

    If you do all this it should help.

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

    by » 11 years ago

    Mark

    Ouch! Gearbox serviced within last 15 hours. New type starter installed. One soft start module installed.

    I will install another soft start module, new sprag clutch and new flywheel. I will let you know how it goes.

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

    by » 11 years ago

    Hi Robert,

    Did things run okay before the maint. You listed above. If they did then its time to check those items before anything new. I didn't think you need all new items, just check out what was already done. This may be the cause of the issues if it ran okay before the maint.

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

      
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