O.S. Engines FS-91S II (P) - Manual (Page 6)

The O.S. FS-70S 2 , FS-91S 2 and FS-91S 2 -P are built, like
all O.S. engines, to the highest engineering standards, by a
company that was established in 1936 to manufacture 2-stroke
engines and which pioneered the production of four-stroke-
cycle model aircraft engines 40 years later.
The FS-91S
2 -P is fitted with the new O.S. PD-07 diaphragm
type fuel pump and matching Type 60N carburettor
incorporating a built-in pressure regulator. These features
ensure that fuel/air mixture strength is maintained at a constant
level through maneuvers, for consistent performance and
reliable throttle response.
In the interests of improved durability, certain steel 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-70S
2 , FS-91S 2 and FS-91S 2 -P are supplied with an
O.S. Type F-4020 baffled silencer (muffler) of substantially
enlarged volume, as standard equipment. Where installation
calls for a separate exhaust pipe and silencer, these parts are
available as optional extras.
INTRODUCTION
Rocker Cover
Cylinder Head
Push Rod Cover
Drive Hub
Propeller Washer
Propeller Nut
Lock Nut
Glow plug Type F
Carburettor Type 60N
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
FS-91S 2 -P
Beam Mount
5