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Dear all,

This is with regards to the Rotax 914 engine cylinders and spark plugs. In the case where the bottom two park plugs from the cylinders (number 2 and 4) were hand-tightened but not fully torqued, will we be able to achieve the RPM requirements (i.e. idle RPM)? Also can we pass the engine test run (in the test cell) even after two hours with such findings?

  • Re: Engine's Performance with Spark Plugs Not Torqued

    by » 3 months ago


    My experience of loose spark plugs is that it often results in a misfire. If they seal sufficiently then the engine will run normally. If plugs are really loose then I have seen melted plug electrodes due to the lean mixture and increased combustion temperature.


    Thank you said by: Ken Lee

  • Re: Engine's Performance with Spark Plugs Not Torqued

    by » 3 months ago


    I have seen people do this in the past and didn’t have an issue other than plug leakage.  Change those plugs, make sure you have your thermal paste on all plug threads, do a compression test just to rule out any issue and then run the engine. Hopefully you should be fine since you said it was only two hours.


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


    Thank you said by: Ken Lee

  • Re: Engine's Performance with Spark Plugs Not Torqued

    by » 3 months ago


     

    Thank you all for the replies.

    Just to add on, we would also like to know that if there will be a difference in idle speed between (i) all eight fully torqued compared to (ii) two bottom spark plugs found hand tightened. i.e. if there will be a difference in idle speed between spark plugs being hand tightened and torqued.

     Also, is it possible for an engine which is tuned to around 2500 rpm idle sped at engine test cell run to experience rpm drop to 1600 rpm when installed at aircraft? If so, what can be the possible causes.

     

     


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