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RPM LOST ON IGNITION CHECK

in 912 / 914 Technical Questions 6 years ago

  • Re: RPM LOST ON IGNITION CHECK

    by » 6 years ago

    I seem to be having similar issues with my 2016 912 uls. Less than 100 hrs. Starts right up, but 1400 + drop on module B at 3800 rpm and it is missing and popping. Still on original plugs. Testing at idle only yields 400 rpm drop and engine runs smoothly on both modules. Synced and checked the carb bowls, swapped plugs, swapped modules, swapped red stator wires, gapped trigger coils, checked their resistance all in the 248 ohm range. All with no noticable change, swapped input coil harnesses and p leads which did lead to opposite switch making the larger drop... Have I overlooked something?
      
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  • Re: RPM LOST ON IGNITION CHECK

    by » 6 years ago

    Could a ignition module be stuck in soft start mode? The issue I'm having seems like a timing issue. Smooth low idle up to 2400 on module B. Then coughs and backfires above 2700. Engine runs great on both.
      
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  • Re: RPM LOST ON IGNITION CHECK

    by » 6 years ago

    Are you sure it's electrical? Have you put a set of carb sync gauges on yet to rule this out. That's cheap and easy to check. Then move on to a more complicated electrical issue. Do you have someone you can swap ignition modules with for at least one start? Do you have separate ignition switches or a rotary switch?ignition

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

      
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  • Re: RPM LOST ON IGNITION CHECK

    by » 6 years ago

    I have synced the carbs three times using two vacuum gauges and have it down to two needle widths apart at 3800 (where I do my checks). I have separate switches. Question is when I swap the pickup connections (the six pin plugs to the triggers) the switches flip, when I change the output connections, nothing changes. Would a module off an older (1994) rotax work for testing purposes?
      
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  • Re: RPM LOST ON IGNITION CHECK

    by » 6 years ago

    Or should I be looking at pickup coils?
      
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