O.S. engine OSM11532 Owner's Instruction Manual page 21

16 Disconnect battery leads
If the engine stops when battery leads are disconnected,
close the needle-valve a little (approx. 30˚) further, and restart
the engine.
Disconnect the battery
leads from the engine
with care so that the
plug clip does not touch
the rotating propeller.
20
17 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 10 -15˚ in the direction of arrow, and
wait momentarily for the change of r.p.m.
After the rpm of the engine is increased, 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.
IMPORTANT NOTE
When fine-tuning the needle-valve to reach peak per-
formance, take care not to run the engine too lean
and cause it to overheat.
Be sure to observe the simple running-in procedures
described on Page 22.
Key to the needle-valve
adjustment.
(Turn 10-15˚ at a time.)