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  • Re: Engine Failure 503

    by » 9 years ago


    I would agree with Bill...with those low EGTs it does sound like its running rich...and that sudden stoppage may have been a rich bog....happens more so if you try and gun the throttle...are the needles in the stock position at the moment,

    I know you have re-built the carbs...but for piece of mind I think I would check all the jets against the book,

    What type of fuel pumps do you have or is it just the std pulse pump...dont suppose your fuel pump could be over-pressurising could it and causing the floats to become to high which will cause a rich mix,

    Can your buddy that lent you his carbs lend you his fuel pump....a pump with a punctured diaphragm can cause odd problems inc excess fuelling...I know this from my outboard motor days...I'm talking about the impulse pump here.

  • Re: Engine Failure 503

    by » 9 years ago


    Hi Bill and Nick the carbys are set to rotax standard .
    as for the exhaust l replace it two hrs early as the first one was cracked on both side of the bend
    they are both standard rotax unmodified exhausts l was told that is crack because it was running to lean and got that hot the vibration caused cracking.
    l am going check the timming today let you know how it goes.
    Fuel Pump is brand new mikuni pulse pump.
    The engine is in a Maxair Drrifter.
    cheers Geoff..

  • Re: Engine Failure 503

    by » 9 years ago


    Hi Again check everything timming l perfect turned the idle mixture screw out one full turn the flat spot has gone engine was is running great .

    l shone a torcth into the carby side just to check pistons were looking good and what did is see the pistons must have grabbed both cylinders have grab marks no the exhaust side so it has been running to lean.

    so here l go again pull motor off start the rebuild all over again .

    cheers Geoff..

  • Re: Engine Failure 503

    by » 9 years ago


    hang fire before you pull the engine apart Geoff,

    I dont understand totally what your saying....you cant see the pistons from the carb side...but if you turned the idle mix out a turn that has the effect of weakening the mixture which is what Bill has been telling you to do by dropping the needles,

    So if you can tell us more about what you have found.

    Nick.

  • Re: Engine Failure 503

    by » 9 years ago


    Hi Nick the rough run at idle and the flat spot was caused by idle mixture been to rich at idle by leaning it out it runs smooth.

    So just for peace of mind l remove the air cleaner turned the engine over until l could see the opposite side and could see scoring so l pulled the exhaust manifold off and the pistons had grab the day she stop in flight.

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