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Do some a hint for the direction of my trouble shooting. My plane is a Europa Aircraft and the engine is a 912ULS. Now reached 90 hours total time since new and under test flight. 

The engine seems to run fine. However I get a lot of soot from the exhaust. It's visible on the wheel spat closest to the exhaust.

The carb needle is set into the second grove (second richest), the floats are adjusted at correct fuel level, new floats 6.5 g, new diaphragm, new needles, new Iridium plugs, newly overhauled ignition but still soothing.

The temperature for Cylinder Head and oil are very low during flight, only around 70 degree C. I can make the temps higher when on the ground and during steep climb. I have covered half of the cooling radiator but still low temp. Outside air temp around 5 degree C. I don't know if the low engine temp can affect the combustion but I include the info just in case.

Hope someone will be able to point me in the right direction.

Regards John

OY-RAF 

Europa Classic Tri Gear.

10350_1_Soot_01.JPG (You do not have access to download this file.)
  • Re: Soot from exhaust

    by » 5 weeks ago


    I have the same setup on my Europa also and had the same issue. It was caused by spending too much time with the choke on. When I start up now I get off the choke as quickly as possible and the spatter has disappeared.


  • Re: Soot from exhaust

    by » 5 weeks ago


    Thank you,

    but I can hardly keep the choke on shorter than I do. I guess it's on for maybe 20 sec. after start.

    John


  • Re: Soot from exhaust

    by » 5 weeks ago


    John

    count from the top of needle down, as shown in the maintenance manual heavy. 

    You might consider this may be related to prop loading.  Too much load, high pitch, can lug the engine and the balance of fuel to RPM can be out of balance.  The CV carburetor is adjusted to give you the leanest burn at about 75% power or about 5000 RPM.  

    Cheers

    39234_2_jet needle settings.jpg (You do not have access to download this file.)

  • Re: Soot from exhaust

    by » 5 weeks ago


    My circlip is installed in grove no 3. That means 2nd reach. That is what I can see is recommended when I fly from ASL and up to 6000 ft.

    However what I find strange is that the fixation screw (#5) on the drawing do not touch the O-ring but allows the needle with the circlip to move slightly up and down. This could give an imprecise position of the needle. Maybe it's within the tolerances, but I can't see what the O-ring is there for, if not keeping the needle in place.


  • Re: Soot from exhaust

    by » 5 weeks ago


    “The temperature for Cylinder Head and oil are very low during flight, only around 70 degree C.” Yes, this could be contributing to your sooty exhaust. You’ve probably noticed condensation at your oil tank when you remove the cap as well? Are you reaching an oil temperature of at least 100c/212f each flight?


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