O.S. Engines FS-120S III - Manual (Page 7)

As supplied, the FS-120S 3 has its throttle lever on the right hand
side and needle-valve control on the left. However, where more
convenient for certain installations, these positions may be
reversed after rotating the carburettor through 180˚ horizontally.
Proceed as follows:
1.
2.
3.
4.
5.
RELOCATION OF CARBURETTOR CONTROLS
Remove the intake pipe mounting screws from the cylinder head
(taking care not to lose the flange gasket) and the carburettor
mounting screws from the crankcase cover plate bracket.
Detach short tube connecting the carburettor to the pump unit
and gently rotate the carburettor through 180
°
without
separating it from the intake pipe or removing the enclosed O-
ring seal.
Re-install the complete sub-assembly of intake pipe and
carburettor, making sure that adjoining surfaces are clean.
Tighten screws evenly and firmly but not excessively.
Remove pump mounting screws from the crankcase cover
plate lugs, carefully rotate the pump clockwise one-quarter turn
and attach it to the second pair of lugs provided, taking care that
the central tube connecting the crank chamber to the pump
diaphragm chamber is not twisted.
Finally, make sure that all external tube connections are secure
and do not leak.
Intake Pipe
Mounting Screw
Intake Pipe
Throttle Lever
Carburettor
Mounting Screw
Needle Valve
FueI Inlet
PD-07 Pump
Pump Fixing Screw
Pressure Regulator
FS-91S 2 -P
6