O.S. Engines FS-120S III - Manual (Page 6)

INTRODUCTION
Rocker Cover
Cylinder Head
Push Rod Cover
Drive Hub
Propeller Washer
Propeller Nut Lock Nut
Exhaust Header Pipe
Carburettor Type 70N
Cover Plate
Crankcase
INSTALLING THE GLOW PLUG
Glow plug
Carefully insert plug, with washer,
fingertight only, before final tightening
with the correct size plug wrench.
Washer
Beam Mount
The FS-120S 3 is the latest mid-range model in the well-estab-
lished FS-120S series of 20cc four-stroke engines. This series
extends from the standard suction-feed FS-120S-E to the
unique ultra-high performance FS-120S-SP, the world's only
production model engine to be equipped with a genuine crank-
shaft-driven supercharger.
The FS-120S
3 is fitted with the new O.S. PD-07 diaphragm
type fuel pump and matching Type 70N carburettor incorporat-
ing a built-in pressure regulator. These features ensure that
fuel/air mixture strength is maintained at a constant level
through manoeuvres, for consistent performance and reliable
throttle response.
In the interests of improved durability, certain ferrous parts that
are particularly susceptible to corrosion in four-stroke engines,
have a corrosion resistant plating and, for the same reason, a
special grease-packed twin-sealed rear ball-bearing is used.
To maintain the four-stroke engine's reduced noise levels, the
FS-120
3 is supplied with an O.S. Type F-5020 baffled silencer
(muffler) of substantially enlarged volume, as standard equip-
ment.
Where installation calls for a separate exhaust pipe and silen-
cer, these parts are available as optional extras. (See page 19
of this booklet.)
F-5020 Silencer
5