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Fly a 914, 1800 hrs, having trouble trying to track down a rough running engine in the rev range of 4800. To. 5200 either side of this engine is smooth, mag check drop is the same , feels like it’s starving for fuel , just had the Carbys overhauled, balance is good , 

  • Re: 914

    by » 5 days ago


    Were your carburetors overhauled by a designated Rotax repair center? The torque for the bolt that holds the float bowl in place is borderline finger tight (49 in. lb), and if they are even slightly over-torqued, it warps the float bowl causing them to leak pressure from the turbo. The float pins can also get pushed to the sides, resulting in the floats getting hung up on the body of the float bowl.

    Did you make any adjustments to the fuel pressure regulator when you were trying to identify this issue or past issues?


  • Re: 914

    by » 5 days ago


    Does sound like carb, rather than ignition, but unusual at that high an RPM.  Mass flow through each carb should be pretty well matched near wide-open-throttle.  Definitely running on the main jet at that RPM.  Check needle on carb slide for wear or damage.  Likewise with main jet itself.  Are EGT's pretty closely matched at 5000 RPM?


  • Re: 914

    by » 3 days ago


    You’re carbs were overhauled. I’d check the needle circlip position,one should be higher than the other. It’s possible they were set up wrong.


  • Re: 914

    by » 3 days ago


    Carbys were overhauled by Rotax tech, clip in right spot, plays up at about 27 on the map gauge, seems worse when the engine heats up , ran it down the strip with carb mate hooked up, once above 4000 it settles on the green , wonder if it could be prop out of balance as can feel more vibe’s through the airframe, starting to run out of ideas, maybe just fly and wait , it’s only in that rpm range


  • Re: 914

    by » 8 hours ago


    Thinking of fitting o2 sensor and maybe be able to see what’s going on , on the 914 exhaust where would be the best place to fit the socket , I was thinking in the dome end above where the tailpipe is located, would that give a good enough reading 


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