O.S. Engines Rotary 49PI - Manual (Page 17)

Prior to releasing your model for take-off, care-
fully check that the engine continues to run
steadily in all flight attitudes: this includes hold-
ing the model with the nose pointing vertically
upwards. In that attitude (assuming the model
to be equipped with a stunt type fuel-tank) the
engine must not quit: if it does, the mixture is
set too lean. Open the needle-valve until the
engine runs safely in this attitude. Adjust the
carburettor (needle-valve and throttle stop)
carefully and make sure that the R/C servo
linkage moves fully and freely between the idle
and full-throttle positions.
PRE-FLIGHT CHECKING
Once the engine has been run-in and the con-
trols properly set up, it should be unnecessary
to alter the mixture settings; except to make
minor adjustments to the Needle-Valve occa-
sionally, to take account of variations in climat-
ic conditions.
The use of a different fuel, however, particular-
ly one containing more, or less, nitromethane
and/or a different type or proportion of lubricat-
ing oil, is likely to call for some readjustment of
the Needle-Valve.
Remember that, as a safety measure, it is ad-
visable to increase the Needle-Valve opening
by an extra half-turn counter-clockwise, prior to
establishing a new setting. The same applies if
the silencer type is changed. A different silen-
cer may alter the exhaust pressure applied to
the fuel feed and call for a revised Needle-
Valve setting. The use of a different glowplug
may also require compensating carburettor re-
adjustments.
SUBSEQUENT READJUSTMENT
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