O.S. engine FS-120S-E - Safety Instructions and Warnings; General Safety Warnings

INSTRUCTIONS FOR
O.S. FS-120S-E FOUR STROKE CYCLE ENGINE
IMPORTANT : Before attempting to operate your
FS-120S-E, please read through these instructions so as to
familiarize yourself with the controls and other features
of the engine. Also, pay careful attention to the recom-
mendations contained in the "Safety Instructions and
Warnings" leaflet enclosed.
INSTALLATION
Use sturdy engine mounting beams: i.e. at least as strong as
would be used for a two-stroke engine of 20cc, or greater,
displacement. Make sure that these beams are firmly
integrated with the airframe, reinforcing the internal sur-
rounding structure as necessary to absorb vibration. Engine
installation should be made in such a way that basic main-
tenance, including the checking and adjustment of valve
clearances, can be conveniently carried out. As an aid to
aligning the engine on its mounting beams, a simple mount-
ing hole template is supplied with the engine.
As an alternative to horizontal beam mounting, a special
O.S. radial motor mount is available, as an optional extra
part, for use where firewall mounting is required.
SILENCER ASSEMBLY
Installation procedure is as follows.
1. Secure the exhaust header pipe by screwing the union-
nut over the cylinder-head exhaust-stub. Adjust the
header pipe to the required angle, then tighten the union-
nut firmly with the 17mm wrench supplied.
2. Screw the silencer onto the end of the header pipe and
tighten locknut firmly.
Note: It is advisable to apply silicone sealant at the joints to prevent
leakage of exhaust gas and loosening of nuts.
CARBURETTOR
The needle-valve and throttle lever locations are inter-
Changeable by reversing the carburettor. This can be done
as follows:
Remove the carburettor carefully by unscrewing the two
screws which secure both carburettor and choke valve. (See
Photo 1.) If the carburettor remains difficult to remove,
slightly loosen the two screws which secure the intake pipe
to the cylinder head.
After reversing the carburettor, re-fit it to the intake pipe
gently, taking care not to damage the O-ring in the carbu-
rettor by using force.
Intake pipe fixing screws
“0” ring
Carburettor
fixing screws
Set screw
Choke lever
Hexagon nut
Cap screw
Choke rubber pad
Photo 1
CHOKE VALVE
The FS-120S-E is equipped with a spring-loaded choke
valve. The choke valve operating lever can be located right
or left by transposing the hexagon nut and cap screw.
After mounting the engine in the model, secure the L-shaped
choke rod by tightening the set-screw. If the rod supplied
is too long, reduce it to the required length. If the rod
length is more than 40mm (1% in.) its outer end should be
Supported to avoid vibration.
SPECIFICATIONS
Displacement 19.96 cc (1.218 cu.in.)
Bore 30.4 mm (1.197 in.)
Stroke 27.5 mm (1.083 in.)
Practical R.P.M. 2,000 ~ 11,000 r.p.m.
Output 1.9 BHP/11,000 r.p.m.
Weight 864 g (30.5 oz.)
FUEL TANK
The suggested fuel tank size is 400cc or 14 oz. This will
give approximately 10 minutes running time when some
part-throttle operation is included. Locate the fuel tank so
that the centre line of the tank is 10 to 15mm below the
centre line of the needle-valve.
Note: If the model is left unattended
with the fuel tank filled, fuel
may flow into the carburettor,
causing it to “flood” and
making the engine difficult to
start. Take appropriate action
to prevent this.
FUEL
The FS-120S-E runs on standard commercially available
model glowplug engine fuel. Fuels containing castor-oil
and/or synthetic lubricants are acceptable, but for the
best performance and reliability, a fuel containing 5 — 15%
nitromethane is recommended.
For consistent performance and long engine life, it is
advisable to use good quality fuel containing NOT LESS
THAN 18% lubricant.
(The carburettor is adjusted with a fuel containing 20%
lubricant when the engine leaves the factory.)
i Centre line
CLH oe
GLOWPLUG
An O.S. Type ”F” glowplug is fitted to the engine.
With a four-stroke engine, ignition of the fuel charge takes
place at every fourth stroke of the piston instead of every
second stroke. Because of this, some conventional two-
stroke glowplugs will not suit this engine. For general use,
the special O.S. Type F glowplug is recommended.
PROPELLER
The choice of propeller depends on the design and weight
of the model and on the type of flying envisaged. Deter-
mine the best size and type after practical experiment. As
Starting points, suggested propellers are listed below.
For stunt models
13x11~12, 14x10~11
15x8, 16x6~7, 17x6, 18x5~6,
14x7 (3-blade), 15x8 (3-blade)
For scale models