O.S. Engines 46FX-H Ring - Manual (Page 16)

A
ADJUSTMENT
The following adjustments are approximately correct
when using a fuel containing 25% lubricant and 10-
30% nitromethane. Bear in mind that fuels containing
relatively large percentages of power-boosting
nitromethane operate at richer mixture settings than
are needed for mild fuels and will, therefore, require
the Needle Valve to be readjusted accordingly. The
type and percentage of lubricant used is also a factor
here, as noted later in these instructions.
This carburetor is not fitted with a throttle
stop screw. Instead, idling speed is adjus-
ted by means of the throttle trim lever on
the transmitter.
This enables the full r.p.m.
range, from idling to full power, to be control-
led by the throttle stick, and then allows the
engine to be stopped, from the transmitter, by
closing the throttle completely with the trim
lever.
Set up the throttle linkage as follows:
With the transmitter throttle trim lever fully
retarded, adjust the throttle servo linkage so that
the throttle rotor is (a) fully open when the
transmitter throttle stick is fully advanced and (b)
fully closed (i.e. engine stopped) when the stick is
fully retarded.The idling speed is then set by
advancing the throttle trim lever to the point
where the engine runs, steadily and reliably,at the
desired idling speed.
As a safety measure, first check the transmitter
controls, including the throttle stick and trim lever
positions, and hold the main rotor securely before
starting the engine.
Warm the engine by allowing it to idle for about 30
seconds. If the engine stops, advance the throttle
trim lever slightly to increase the idling rpm. Then
open the throttle sufficiently to 'float' the model
above the ground.
B
C
Open the Needle Valve 2 turns from the fully
closed position.(Be sure to use a muffler-
pressurized fuel feed.)
NOTE:
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