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Carb sync for beginners

in 912 / 914 Technical Questions 12 years ago

  • Re: Carb sync for beginners

    by » 11 years ago

    I made research today:
    I checked parameters ang plugs colors again after 4min @ 4100RPM. One side was much darker so I leaned next 1/4 turn rich side carb.

    After this spark plugs color started to look equal (left and right pair). I'll check it again after 20min flight and see again.
    I have still problem with this ETG

    Movie after tuning:
    https://www.youtube.com/watch?v=wem2aN0XANU

    This table shows EGT reading before today leaning and after:



    As I can see my max side difference is 121*C and it's 10* less after leaning rich side today. Averange temperatures now are better but still I have big spread on one side.


    After today tuning my spark plugs looks like:

    Pto lean side

    Pto rich side


    Rich mag side:

    Lean mag side



    It was after 4 min at 4200RPM, 5s on 2000 and shutdown.
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  • Re: Carb sync for beginners

    by » 11 years ago

    Pneumatic synchronization is ideal for all range of throttle. I checked if levers are going the same - it looks ideal.
    I have new lines and teflon shields for steering lines.
      
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  • Re: Carb sync for beginners

    by » 11 years ago

    I looked at your video. The EGT temps are bouncing all over. They shouldn't be. They may change depending on a specific throttle setting, but left alone should stay at a specific temp fairly well. They may move a little, but not like yours. I would be looking for a poor connection on the electrical side of things. The plugs don't look bad at all. Remember they are new so they won't show as much as a plug that has 20-50 hrs on it. The plug gap looks to be a little too tight in the picture? Is it between .023 and .027? The hotter the out side air temp the wider the gap and the colder the OAT the narrower. So winter cold months get a narrow gap and the summer hot months get a wider gap. What did you do to lean the carb? The mixture screw on the bottom isn't going to affect the high rpms. Part of the dry black soot at times comes from long idles and difference in the length of the air intake manifold and air flow through these.

    I would leave the carbs alone and find out why the EGT's all bouncing so bad. They are bouncing over
    45c-55c.

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

      
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  • Re: Carb sync for beginners

    by » 11 years ago

    Hi. I set every spark plugs between 0,6 and 0,7 mm using feeler (special tool). Now winter is coming.
    I leaned carb using 961-222 screw.
    Every egt sensor is two wire (white and green). Ground problem will affect this sensors? I can't guarantee that exhaust collector is well grounded - it's on ball connections so probably not.
      
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  • Re: Carb sync for beginners

    by » 11 years ago

    That screw (961-222 idle mixture screw) is okay for the idle mixture, but won't help for the high rpms. I would leave that at 1.5 turns out. What is your airport elevation?

    I would look real hard at making sure the grounding is solid and there is no corrosion on any contact. Make sure the engine is well grounded and the instruments.

    Poor grounding (earthing) will cause this and or a bad or corroded connection..

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

      
    Report
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