O.S. Engines 65AX - Manual (Page 19)

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CARE AND MAINTENANCE
Please pay attention to the matters
described below to ensure that your engine
serves you well in regard to performance,
reliability and long life.
As previously mentioned, it is vitally important
to avoid operating the engine in conditions
where dust, disturbed by the propeller, may
be deposited on the engine and enter its
working parts.
Remember to keep your fuel container
closed to prevent foreign matter from
contaminating the fuel.
Install a fuel filter to prevent dirt and dust in
the fuel container from entering the fuel tank.
O.S. Super Filters (L) and (S) are available
as optional extras.
Install an in-line fuel filter between the tank
and carburetor to prevent dirt and dust in the
tank from entering the carburetor.
If these precautions are neglected, restriction
of fuel flow may cause the engine to cut out,
or the fuel/air mixture to become too lean
causing the engine to overheat.
Clean these filters periodically.
The use of modern high-performance alcohol
based model engine fuels, while promoting
cooler running, improved anti-detonation
combustion and increased power, have the
disadvantage of causing corrosion due to the
acid by-products of combustion. The use of
nitromethane in the fuel can also contribute
to the problem.
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Do not close the needlevalve and mixture
control valve too far as this will cause a lean
setting and over heating of the engine. This
can, in turn, create nitromethane oxide
leading to internal rusting of the engine.
Always adjust the needlevalve slightly on the
rich side of peak rpm.
Do not leave unused fuel in the engine at the
conclusion of a day’s flying. Accepted
practice is to cut off the fuel supply while the
engine is still running at full throttle, then
expel as much fuel residue as possible by
turning the engine over 5-10 seconds with
the electric starter. Finally, inject some after-
run oil through the glowplug hole and turn the
engine over several times by hand.
When the engine is not to be used for some
months (for example, as between flying
seasons), a worthwhile precaution is to
remove it from the airframe and, after
washing off the exterior with alcohol (not
gasoline nor kerosene), remove carefully the
carburetor, glow plug and all silicone tubing
and put them safely aside. Then, immerse
the engine in a container of alcohol. Rotate
the crankshaft while the engine is immersed.
If foreign matter is visible in the alcohol, rinse
the engine again in clean alcohol. Finally,
shake off and dry the alcohol ,and inject
some after-run oil in the glowplug hole and
rotate the crankshaft several times by hand.
Reinstall the carburetor and glowplug on the
engine and keep it in a dry place after putting
in a vinyl bag.