O.S. Engines FS-40S - Manual (Page 20)

20
~
30
°
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.
Key to the needle-valve
adjustment.
(Turn 15-30˚ at a time.)
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.
16 Needle-valve adjustment(Summary)
Practical best(optimum) needle-valve setting
Disconnect battery leads from
glowplug at about this point.
Maximum rpm setting("Lean").
"Rich" needle-valve
setting when starting
the engine.
E ngine
stops
R
e
v
o
lu
ti
o
n
s
s
ta
rt
t
to
d
e
c
re
a
s
e
.
to
d
e
The engine may stop if the battery leads
are disconnected from the glowplug while
the engine is running rich.
NOTE: The above sketch is for reference purposes only.
Actual needle positions may differ from those shown.
19