Care And Maintenance 20 - O.S. engine FS-52S Owner's Instruction Manual

Remove 0.04mm feeler, rotate prop through two
5.
revolutions and recheck gap.
6.
If clearance is correct, loosen the locknut on the
other rocker-arm and repeat steps 1 to 5 above.
Finally, replace rocker box cover.
Remember:
Excessive valve clearance will cause loss of
power, due to valve (s) not opening sufficiently.
On the other hand, a total loss of clearance may
cause difficult starting due to valves not closing
properly, resulting in loss of compression.
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,
stirred up by the propeller will be ingested into the
engine resulting in damage to the internal parts. Also,
remember to keep your fuel container closed to
prevent foreign matter from contaminating the fuel.
Do not forget to clean the fuel filters periodically and,
from time to time, unscrew the complete needle-valve
assembly from the carburettor and remove any
foreign matter that has accumulated in this area. (See
photo.) 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. 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 in four-stroke engines, of a tendency to
cause bottom end corrosion if not checked. This is
because the acidic by-products of combustion, some
of which contaminate the oil in the crankcase, are not,
in a four-stroke, diluted and flushed out by the flow of
fresh fuel mixture through the crankcase as in the case
of a two-stroke engine. Such contamination (made
worse if the fuel also contains a high proportion of
power boosting nitromethane) can cause rusting of
steel parts. As noted earlier, the FS-52S has its most
vulnerable internal parts protected against such attack
but, as a primary defence, users are advised, once
again, to avoid running the engine on too lean a
mixture and by making sure that the engine is flushed
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