Hello All, I have an issue with my Rotax 912ULS engine. Total 60 hours. The prop is an Airmaster c/s.
When in cruise around 5000 rpm the engine suddenly runs a little rough for a second or so. I can feel small ‘kicks’ from the engine and the rpm drops 50-100 rpm. But just very short before it goes back to normal, but just to misfire again after a few seconds or sometimes after half a minute. I don’t feel anything when under full load at T.O. I do not have a drip-tray (heat shield) under the carburetors.
Have some of you an idea about in which direction to trouble-shoot.
  • Re: Rough running around 5000 rpm

    by » 10 months ago

    I would do a few things first. Install the heat shield / drip trays for safety. Then perform a carb sync. Make sure both throttles are opening all the way and pop the carb bowls off and make sure they are clean inside and the floats move freely. Is fuel pressure stable? Leave no stone unturned because sure enough when we do it's the issue. Just be thorough.

    Plus not all vibrations are engine caused. Consider other causes.

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

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