O.S. engine FS-30S Owner's Instruction Manual page 10

Check that the throttle is one-third open from the fully
closed position. Bring the starter into contact with the
spinner nut or spinner and depress the starter switch
for one or two seconds. Repeat if necessary. When
the engine fires, withdraw the starter immediately.
Attention: Never place your finger over the
carburetor intake when applying the starter. Such an
action will cause an excess quantity of fuel to be
drawn into the cylinder and result in hydraulic lock
that may damage the engine.
12 Engine starts
In the interests of safety, keep your face and other parts of the
body away from the vicinity of the propeller.
15 Needle-valve adjustment(2)
As the needle-valve is closed beyond the initial readjustment,
the rpm of the engine will be increased and a continuous high-
pitched exhaust note, only, will be heard.
Turn the needle-valve 15-30˚ in the direction of arrow, and wait
momentarily for the change of r.p.m.
After the rpm of the engine increases, turn the needle-valve
another 10-15˚ and wait for the next change of r.p.m.
As the speed of the engine does not instantly change with
needle-valve readjustment, small movements, with pauses
between, are necessary to arrive at the optimum setting.
13
Slowly advance throttle to its
fully
gradually close the needle-
valve until the exhaust sound
changes pitch.
Close the needle-valve gradually until a
high-pitched exhaust note begins to be
superimposed on the lower-pitched
sound.
14
Disconnect the battery leads
from the engine with care so
BEWARE of
that the plug clip does not touch
the rotating
the rotating pro-peller.
propeller.
If the engine stops when battery
leads are disconnected, close
the needle-valve a little (approx.
45˚) further, and restart the
engine.
18
16
Practical best(optimum) needle-valve setting
Key to the needle-valve
adjustment.
(Turn 15-30˚ at a time.)
Disconnect battery leads from
glowplug at about this point.
NOTE:
The above sketch is for reference purposes only.
Actual needle positions may differ from those shown.
19
Needle-valve adjustment(1)
open position, then
Listen to the sound
carefully.
Disconnect battery leads
Needle-valve adjustment(Summary)
Maximum rpm setting("Lean").
20-30˚
The engine may stop if the battery leads
are disconnected from the glowplug while
the engine is running rich.
"Rich" needle-valve
setting when starting
the engine.