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Vibration

in 912 / 914 Technical Questions 7 years ago

  • Re: Vibration

    by » 7 years ago

    That is correct, however most 12 drivers will tell you that right EGT runs about 100F hotter than left EGT.
      
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  • Re: Vibration

    by » 7 years ago

    Thanks Jim, I had heard that as well. I see a difference >120 F (right is higher as you note), but only in the RPM range where I feel the vibration. At 5200-5500 the engine smooths out, and the EGT difference narrows to <25 F. Are you seeing the EGT difference go away at higher RPM settings?
      
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  • Re: Vibration

    by » 7 years ago

    EGT temps are affected by throttle position and change with its position. I have seen EGT's close to equal and 100F apart. If temps are more than 120F apart you may want to check into that. Remember EGT temps are a product of the fuel burn. If you use header wrap (which is no problem) make sure you do not over wrap on the EGT probe. It will distort and cause temp fluctuations through the probe. Leave a tiny gap at the probe edges. Things like carb sync, plug gap and air leaks, poor placement of diaphragm and dirty carbs are a few items that can affect temps.

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

      
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  • Re: Vibration

    by » 7 years ago

    I never really checked EGT's on my 12 at lower RPM's because its way down on the power curve and doesn't make any difference there. At cruise I show about 100F difference with the right side always higher. According to other folks this is pretty normal for the RV-12 installation. You should be running 5000-5500 in cruise. Slower is not good for the engine. I think you are OK with the readings you show. Prop pitch should be set to allow ~ 5650 full throttle in level cruise at whatever altitude you will normally fly at.

    There are RPM bands where vibration will be present. Engine and prop combinations often have harmonic vibration do to inherent design. Best to not dwell where vibration is present and power up to cruising RPM where everything is happy and playing well with each other.
      
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  • Re: Vibration

    by » 7 years ago

    Barry,

    I experienced very similar results on my 912ULS in a Kitfox. I found one sinking float in my carb. I have the 2 dot floats "known Good" in the latest SB. I had replaced the original floats in the prior SB. The Hard part if finding replacement floats in stock or even finding out when floats will be in stock. I am waiting for CPS to get back to me. Leaf is out of stock. Anyone know where else I can chase some floats down?

    Thanks

    Scott
      
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