O.S. engine FS-70 Ultimate Owner'S Instruction Manual Download

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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
for 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 or kerosene) to carefully
remove the fuel pump, carburetor with intake pipe and all
silicone tubing and put them safely aside.
Make sure that the engine is reasonably clean externally, then
remove the glowplug and immerse the engine in a container
of kerosene. Rotate the crankshaft while the engine is
immersed. If foreign matter is visible in the kerosene, rinse the
engine again in clean kerosene, before removing it, vigorously
shaking off the excess and wiping it dry.

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. 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 carburetor 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 of causing bottom end corrosion in a four-stroke
engine. This is due to the acidic by products of combustion that
accumulate in the engine's crankcase and are not flushed out
by fresh air/fuel mixture as in the case of a two-stroke engine.
The use of nitromethane in the fuel can also contribute to the
problem. As noted earlier, the FS-70 ULTIMATE

has it most

vulnerable components 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 purged of contaminants as much as possible.

CARBURETOR EXPLODED VIEW & PARTS LIST

25581900
22681980
24981837
26381501
27381940
26711305
44781100
21285220
45571000
44781650
46066319
24881824
44781200
44781400
45515000

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