I have a rotax 503 that quits in flight do you know the problem

SOURCE: rotax 503 i do not trust anymore scarry stuff!when it stops close to ground

Be good if you asked your question...

Rotax seem to have a decent reputation but the 2-stroke engine has a number of disadvantages compared with the 4-stroke though the major advantage of the 2-stroke, the lighter weight and superior power to weight ratio capability of the 2-stroke makes that type of engine more desirable for a number of applications.

Most of the disadvantages can be reduced by careful building to very fine tolerances, what is know as "blueprinted". That goes some way to explain why those engines approved for use in aircraft cost more than double of those used on the ground.

While a blueprinted engine that is better balanced is less likely to suffer serious mechanical failure due to sustained high revolutions in the way an earthbound engine probably would, it doesn't make them immune from such things as whiskering spark plugs, spark plug oiling, dirty fuel, ignition failure or carburettor icing.

The aero engine is a superior build and it needs superior maintenance and routine attention, carried out as if a surgeon operating on a person just as a mechanic of a formula 1 racecar would but even then problems won't be eliminated - merely shift the odds to more favourable...