I have a MTO Sport gyrocopter of 2007 vintage (635 hours).

Just young enough to have the new crankcase and the red ignition modules.

This engine has served me well for around 100 hours. Never a problem, smooth running.

But just a few weeks after a nice evening flight I wanted another.

And the engine was dead - completely. Scratching my head... From smooth to dead...

After some troubleshooting - lots of fuel coming to the carb bowl (just tested one).

Nothing wrong with the grounding "mag" swithces - and wire all the way back to the ignition modules ok.

Then I ohm'ed the different coils - all values were in range. Then it had to be the 2007 ignition modules, right?

After I tested the coils and plugged it all together (again) the engine started up. Strange - some bad connection...?

But now it runs rough above 3200-3700 RPM... like the propeller is out of balance - in a strange way.

New modules - nothing changed. Oops - two spark plug caps weren't fully inserted - just looked like they were.

Nothing changed. Newly cleaned and oiled air filter taken off - nothing changed. Now I am at a loss.


(since the engine wouldn't start, I changed the oil and coolant hoses. That's another beehive by itself)


I haven't touched the well-balanced carbs at all. Except having had the bowl off one to check fuel flow.

What to do now?



  • Re: 914 Woes...

    by » 11 months ago

    There's a great video about fault-finding the ignition system here: https://www.rotax-owner.com/en/videos-topmenu/free-videos/695-Rotax-lockwood-ignition-troubleshooting

    You need to determine if you have a fuel, ignition or mechanical problem. The fact that you had a non-running engine does suggest ignition unless there is no fuel getting through to the carbs.

  • Re: 914 Woes...

    by » 11 months ago

    Hi Kevin.

    Thank you for giving that link.

    I have had two problems - at first no ignition. Now I think I have a carb problem.

    And since the only thing I did, was to remove the float bowl and check the fuel flow.

    I now believe I must have assembled the carb incorrectly, so the fuel flow is restricted somehow.

    Because warm-up was faster than usual...

  • Re: 914 Woes...

    by » 11 months ago

    Hi again.

    Oh, I can see, it looked like I snubbed you off - sorry, I didn't mean to...



  • Re: 914 Woes...

    by » 11 months ago

    No problem.

    If you suspect that the carbs are incorrectly assembled then I would remove them, strip them and rebuild them according to the heavy maintenance manual. Look closely at everything, including the 3 small drillings in the venturi. Spray some carb cleaner through the jets and mixture adjustment needle.

    Check the O-rings and other rubber components for damage. Make sure that the butterfly valve is free to move in the venturi. Check that the main needle assembly is free to slide in the body.

    Could there be a valve issue? Have you done a leak-down test to rule out internal problems?

  • Re: 914 Woes...

    by » 11 months ago

    Hi Kevin.

    It looked like a carb problem. Ok idle and probs rising with RPMs.

    But I checked the float bowl yesterday - all was well.

    The thing is, I have used it 100 hours - 100% great service.

    Even after ½ a year standing still, it jumped right at it when I showed the key.

    This year I flew 35 hours in may/june - flew it home over a large stretch of water at FL 70.

    Then I had two flights and the third couldn't happen.

    No spark at all. From 100% to none...

    I now have two Ignitech modules mounted.

    The coils have the correct resistance values.

    I just checked the spark plugs today - nothing out of the order.

    I'll clean them and attach them tomorrow.

    Then I'll do as Dean Vogel suggested to ascertain, if it's an ignition or a carburetion problem.

    Maybe I disturbed something, when I changed the hoses...



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