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Rough at low RPMs

in 912 / 914 Technical Questions 9 years ago

  • Re: Rough at low RPMs

    by » 9 years ago

    Hi Mark,

    The idler jets are at 1 1/2 turns out. I haven't cleaned anything yet. I have never used ethanol fuel or 100LL either so it didn't seem necessary at 175 hrs. I will clean the idle circuits and check the float arms when I can find a little time. Richard
      
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  • Re: Rough at low RPMs

    by » 9 years ago

    Have you tried to read A/f values with wideband A/F gauges?
    I have problems with the engine goes too rich between 2500 and 3500 at descending. A/f values is below 10.2. The result is that the engine runs rough. I use standard settings on the carburetors.
    I can lower the needle, but then it goes too lean at WOT and cruise (15.0)


    Øystein Aaneby
      
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  • Re: Rough at low RPMs

    by » 9 years ago

    As the mixtures, at idle, are pretty much way out out of syn between the cylinders, could it be the rich cylinders leaning out, therefore making slightly more power ( hence the increased rpm) and improving the running/balance of the engine?
      
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  • Re: Rough at low RPMs

    by » 9 years ago

    Hi Mark, It looks like you were right on. I re-read the rotax maintenance manual as a last resort (tradition with males I know not to read instructions until everything else fails):) . Section 10.5 says to turn the mixture screw clockwise to make a leaner mixture. I had followed the CARBTECH page at leadingedge airfoils.com and it said CCW for a leaner mixture. I was going the wrong way and it was not helping. Turning it CW 1/4 from the 1 1/2 turns out point made all the difference. Idle speed is 1950 and it is so smooth. So simple. Thanks for making me rethink that.
      
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