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3.
Fill the fuel tank. Do not allow fuel to overflow into
the silencer, otherwise the engine may become
flooded and difficult to start.
4.
Check that the needle-valve is closed. (Do not
overtighten.) Now open the needle-valve counter-
1
clockwise 1
-2 turns to the starting setting .
2
Mark
Turn needle-valve clockwise to close
(for leaner mixture)
Turn needle-valve counter-clockwise
Close
to open (for richer mixture)
Open
5. Open the throttle approx. one-quarter.
(This is to avoid unnecessarily
high r.p.m. when the engine starts.)
Fully closed
Fully opened position
position
3
1
4
4
Set at this point
RUNNING-IN ("Breaking-in")
All internal-combustion engines benefit from extra
care when they are run for the first few timesknown
as running-in or breaking-in.
This allows the working parts to mate together under
load at operating temperature. Therefore, it is vitally
important to complete the break-in before allowing the
engine to run continuously at high speed and before
finalizing carburetor adjustments.
However, because O.S. engines are produced with
the aid of the finest modern precision machinery and
from the best and most suitable materials, only a
short and simple running-in procedure is called for
and can be carried out with the engine installed in the
model. The process is as follows.
Install the engine with the propeller intended for
1.
your model. Open the needle-valve to the advised
starting setting and start the engine. If the engine
stops when the glow plug battery disconnected,
open the needle-valve to the point where the en-
gine does not stop.Run the engine for one minute
with the throttle fully open, but with the needle-
valve adjusted for rich, slow "four-cycle"operation.
6. Connect battery leads to glowplug.
7.
Bring electric starter into contact with spinner-nut
or spinner and depress starter switch for one or
two seconds. Repeat if necessary.
When the engine starts, withdraw the starter im-
mediately.
Attention :
Do not choke the carburetor air intake when applying
the starter. This could cause an excessive amount of
fuel to be drawn into the cylinder which may initiate
an hydraulic lock and damage the engine.
If the engine does not start within 10 repeat
applications of the starter, remove the glow-plug,
check that it glows brightly and that the cylinder is not
flooded with fuel. (To eject excess fuel, close needle-
valve and apply starter with glowplug removed.) Then
try again.
VERY IMPORTANT!
Before being operated at full power (i.e. at full-throttle and
with the needle-valve closed to its optimum setting) the
engine must be adequately run-in, otherwise there is a
danger of it becoming overheated and damaged.
18
2.
Now close the needle-valve until the engine
speeds up to "two-cycle"operation and allow it to
run for about 10 seconds, then reopen the needle-
valve to bring the engine back to "four-
cycle"operation and run it for another 10 seconds.
Repeat this procedure until the fuel tank is empty.
Re-start and adjust the needle-valve so that the
3.
engine just breaks into "two-cycle" from "four-
cycle" operation, then make three or four flights,
avoiding successive "nose-up" flights.
4.
During subsequent flights, the needle-valve can be
gradually closed to give more power.
However, if the engine shows signs of running too
lean, the next flight should be set rich. After a total
of ten to fifteen flights, the engine should run
continuously, on its optimum needle-valve setting,
without loss of power as it warms up.
5.
After the completion of the running-in adjust the
carburetor at optimum setting referring to
MIXTURE CONTROL VALVE ADJUSTMENT
section and SUBSEQUENT READJUSTMENT
section.
19
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