O.S. Engines FT-300 Gemini User Manual
Page 11
Battery Leads
As the battery leads are required to conduct a large current
(approx. 6 amps), make sure that the wire used is heavy
enough to prevent excessive voltage-drop at the plugs.
Note: It is inadvisable to use a variable resistance or rheostat as, in
the event of one plug lead becoming accidentally detached
(or the plug element failing) excessive voltage will be applied
to the other plug. The alternative is to use a separate battery
and rheostat for each plug.
STARTING
It is preferable to use an electric starter, although hand-
starting is also possible, as will be explained in a moment.
When applying the starter, be sure to connect both glow-
plugs to the battery.
(It is possible to start the engine on one cylinder only, then
to connect the other glowplug to the battery to run the
engine on both cylinders, but this is not advisable since it
causes needlessly unequal loading of the engine initially.)
1) Open the throttle fully and unscrew the needle-valve
3-1/2 turns from the fully closed position.
2) It is preferable to use the choke control for priming.
3) Close the choke valve and turn the propeller counter-
clockwise 2 turns by hand keeping the throttle valve
fully open.
4) Release the choke control and immediately turn the
propeller counter-clockwise several times so that fuel is
drawn well into the cylinders.
5) Set the throttle valve approximately 1/3 open from the
fully closed position. Connect the glowplugs to the
battery and apply the electric starter.
6) When the engine starts, open the throttle valve fully and
keep it running, initially (approx. 10 seconds), with the
original needle-valve setting. If the engine slows down
because the mixture is excessively rich, close the needle-
valve slowly approx. 1/4 — 1/2 turn.
7) Now disconnect the battery from the glowplugs and
close the needle-valve slowly so that revolutions are
increased. Adjust the needle-valve gradually. Abrupt
adjustment of the needle-valve may cause the engine to
stop, especially when it is new and insufficiently run-in.
8) To re-start the engine when warm, simply re-energise the
plugs and reapply the starter with the throttle in the
idling position. If the engine does not restart, re-prime
by closing the choke valve while rotating the propeller
twice with the throttle open. Initially, the high tempera-
ture inside the combustion chambers may turn the liquid
fuel into gas and emit it through the exhaust pipes.
Therefore, repeat the priming procedure once or twice
until the cylinders become cool enough for restarting.
CAUTION: Never apply an electric starter with the choke closed.
Such action will cause an excessive quantity of fuel
to be drawn into the cylinder and result in an
hydraulic lock that may damage the engine. Do not
turn the propeller more than 2 turns, initially, with
choke closed, otherwise the engine may suck in too
much fuel and become flooded.
CAUTION: Do not connect the glowplugs to the battery when
priming. The adjustment of the needle-valve should
be done only after disconnecting the battery from
the glowplugs.
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