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EGT 200 f increase and 500 RPM drop on mag check

in 912 / 914 Technical Questions 4 years ago

A new one I can not figure out. Carbs synced, new rotax spark plugs with rotax caps, changed electronic ignition modules as attempts so far. Intermittent but problem is: 4000 rpm mag check a off 912 80 hp 500 rpm drop with EGT rising from 1300 to 1560. Mag check b off 300 rpm drop and EGT rose slightly. Past my understanding what is happening. Any experience or thoughts?

  • Re: EGT 200 f increase and 500 RPM drop on mag check

    by » 4 years ago

    How many hours since your carbs were rebuilt?

      
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  • Re: EGT 200 f increase and 500 RPM drop on mag check

    by » 4 years ago

    I helped a friend a year ago with excessive mag drop after ruling out ignition it turned out the carbs needed cleaning and new o-rings. Just cleaning the idle jets helped some but a rebuild solved the problem. So the excessive rpm drop was mixture related.

     

    Thank you said by: Nicholas Wilcox
      
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  • Re: EGT 200 f increase and 500 RPM drop on mag check

    by » 4 years ago

    My thoughts are that a Mag Check is Ignition (Spark) related.
    Nothing fuel-related changes when you shut OFF a Mag.
    When a plug misfires, the fuel mixture is igniting as it passes the glowing EGT Sensor producing the EGT Increase.

    Are you also experiencing some roughness with the RPM decrease/ EGT Increase?

    Bill Hertzel
    Rotax 912is
    North Ridgeville, OH, USA
    Clicking the "Thank You" is Always Appreciated by Everyone.

    Thank you said by: Nicholas Wilcox
      
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  • Re: EGT 200 f increase and 500 RPM drop on mag check

    by » 4 years ago

    Bill Hertzel wrote:

    My thoughts are that a Mag Check is Ignition (Spark) related.
    Nothing fuel-related changes when you shut OFF a Mag.
    When a plug misfires, the fuel mixture is igniting as it passes the glowing EGT Sensor producing the EGT Increase.

    Are you also experiencing some roughness with the RPM decrease/ EGT Increase?

    Hi Bill, this post by Paul is about my trike. To answer your question, yes, we are experiencing some roughness with the RPM decrease/EGT increase on the A side mag check. 

    I agree with your assessment, but finding the spark issue has been tough. All resistance values are within tolerance for respective components. All new plugs and caps. Swapping the control modules doesn’t change issue on A ignition side. Thoughts on finding spark issue? Thanks 

      
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  • Re: EGT 200 f increase and 500 RPM drop on mag check

    by » 4 years ago

    Garrett Wysocki wrote:

    I helped a friend a year ago with excessive mag drop after ruling out ignition it turned out the carbs needed cleaning and new o-rings. Just cleaning the idle jets helped some but a rebuild solved the problem. So the excessive rpm drop was mixture related.

    Wouldn’t carb related be on both mag sides and not just one, given wiring setup? 

      
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