In the past week I have noticed engine roughness ONLY at 2500 to 3200 RPM. The idle down to 1400 is smooth. This is a 912UL with 230 hrs total time. Last winter I raised the needle valves. It is now 15 to 20C most days. Should I be lowering them again? Carbs are synced and plugs are new. Any suggestions
  • Re: Engine Roughness

    by » 8 years ago


    The RPM range of 2500 - 4000 is the range that is most affected by the needle positions.
    It is a good possibility that for your configuration, and the change to warmer conditions, moving the needles back down to their previous positions (likely the second notch from the top) will result in smoother operation in that RPM range.

  • Re: Engine Roughness

    by » 8 years ago


    I changed the needle positions back to summer mode(second notch from the top) and it smoothed out a lot. Also ordered a Carbmate and will recheck the sync when it arrives.
    Thanks for the help.
    Don

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