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drop rpm

in 912 / 914 Technical Questions 14 years ago
I have a problem with the engine ROTAX 912 when I start running to takeoff I have drop the fall of 300 rpm.
Can someone give me an idea how to solve the problem?

  • Re: drop rpm

    by » 14 years ago

    what happens when you take it to wide open throttle on the ground before you takeoff...like during your run-up.
    Thank you said by: Moshe Ferera
      
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  • Re: drop rpm

    by » 14 years ago

    Hi Moshe,

    A little more info would be helpful.
    If you do a mag drop at 3500-4000 what do you get? If it is fairly equal and not excessive then it's time to look at the fuel/carb delivery.
    Have you balanced the carbs? Have you looked in the float bowl? By doing so at times you may see a large disparity in vacuum. I don't mean to just run it up to 2500 rpm like some people. Run it up to at least 4000 rpm and see how the needles on the gauges respond. I have found several carbs with debris in them that way. If a carb does look like it may have an obstruction you can get a good idea which one then pull that carb and blow out and examine each passage. The one pulling the most vacuum is the one with an obstruction. By checking the carbs you can also make sure the diaphragm is in properly and while the carb is off you might as well double check the float arm height. I just had a situation like this and found a piece of red silicone in a passage way.

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

    Thank you said by: Moshe Ferera
      
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  • Re: drop rpm

    by » 14 years ago

    I had a similar problem with my 912UL a couple of years ago. The engine would run OK for the power checks but at full power on the take off roll the engine would cough and splutter. It turned out to be some particles in the carb float chamber. After I cleaned them out it was fine and I have not had any more problems.
    Thank you said by: Moshe Ferera
      
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  • Re: drop rpm

    by » 14 years ago

    Hi Kevin..
    Thank you for advice. I see what you recommended me to notify you of your..
    beautiful week ..

    Regards.
    Ferera Moshe
      
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  • Re: drop rpm

    by » 14 years ago

    Dear friends .. :cheer:
    I found the problem ..! After investigations of carburator not found anything I concluded that maybe exhaust is the problem .. dismantled the exhaust and I found parts, Parts I found reduced the amount of gases emitted from the engine strangled and drop the rpm.
    I thank you all for the good will .. :)
    maybe it will help future similar problems

    best regards.
    Ferera Moshe.
    :woohoo:
      
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