O.S. Engines FS-200S - Manual (Page 12)

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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)
is available as an optional extra.
Install an in-line fuel filter between the tank and carburetor
to prevent foreign matter 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.
Do not close the needle-valve 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.
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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 with intake pipe,
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
with intake pipe and glowplug on the engine and keep it in a
dry place after putting in a vinyl bag.