O.S. Engines GT60 - Manual (Page 3)

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When starting the engine for the first time, set both the
high speed needle 2 turns open and the slow speed
needle 2 turns open from the fully closed position.
With this position both high and slow speed mixtures
will be rich. If the settings are upset, come back to this
setting and adjust them according to procedure in the
needle setting section.
Initial needle position
Starting by an electric starter
Turn on the transmitter switch.
Turn on the receiver switch.
Turn on the ignition switch.
Open the choke valve fully (OFF).
Pull the the transmitter throttle stick to the fully or
1/8 open position so that the engine starts at low
speed ( 2 to 3 clicks). If the throttle stick is opened
too far the engine can roar to life when the electric
starter is applied allowing the aircraft to jump
forward which is dangerous and could result in
injury.
Tell the helper and onlookers that you will start the
engine now and have the helper hold the model
securely.
Apply the electric starter.
Note
If you have only short runs or the engine does not
start with more than 5 flips, most probably priming
is not sufficient. Remove the plug to check if it is
wet.
If it is wet, replace it or wait until it becomes dry.
Then, flip the propeller quickly 10 times without
installing the plug to eject the fuel in the engine.
Then, install the plug and repeat the procedure.
1/4 1/2 3/4
NEEDLE ADJUSTMENTS
The slow speed needle is effective through the
high speed range, while the high speed needle is
not effective in the low speed range. Both needles
are effective in the mid speed range, while the
slow speed needle is the most effective. (Refer to
the diagram below.)
Fuel Flow
Throttle
Opening
Fully
open
More
Less
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Carry out the needle settings as follows.
Adjustment on the ground
Set the high speed needle 2 turns open and the
slow needle at 2 tuens open from fully closed
position.
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3. Set the throttle stick 2-3 clicks advanced from the
bottom and measure rpm with a tachometer and
write it down.
Close the slow speed needle approx. 30 degrees
and measure rpm with a tachometer and write it
down. (Be sure to adjust the slow needle only after
stopping the engine.)
Repeat step 4. to locate the slow speed needle
position where maximum rpm is achieved. Open it
approx. 180 degrees from this position. This is the
basic slow needle position.
Open the throttle valve fully and measure rpm with
a tachometer and write it down.
Close the high needle approx. 30 degrees and
measure rpm and write it down. (Be sure to adjust
the high needle only after stopping the engine.)
Repeat step 7. to locate the high needle position
where maximum rpm is achieved. Open it approx.
60 degrees from this position. This is the basic
high needle position.
Set the throttle trim on the transmitter so that the
idle rpm is approx. 1,800 (approx. 1,600rpm when
idle down function is used).
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Warm the engine for 10 seconds with the throttle fully
open, then idle the engine for 5 seconds, then quickly
open the throttle fully. Make sure the engine does not
respond sluggishly to increase rpm nor hesitates
before picking up speed or even ceases firing.
If the engine responds sluggishly to increase rpm,
the mixture is too rich due to the slow speed needle
being open too far. Close the slow speed needle
approx. 15 degrees. Repeat this procedure until the
engine accelerates smoothly. (Be sure to adjust the
slow speed needle only after stopping the engine.)
If the engine hesitates before picking up speed or
ceases firing, the mixture is too lean due to the
slow speed needle being open too far. Open the
needle approx. 15 degrees. Repeat this procedure
until the engine accelerates smoothly. (Be sure to
adjust the slow speed needle only after stopping
the engine.)
Adjustment with flight
If the rpm drops or the exhaust sound weakens
when vertically climbing from level flight with full
throttle, the mixture is too lean. Land the model
and open the high speed needle approx. 15
degrees. Repeat this procedure until the engine
sound is smooth.
If the above symptom is not detected with
prolonged torque roll and hovering but sluggish to
increased rpm when the throttle is fully opened
abruptly, the mixture is too rich. Land the model
and close the slow speed needle approx. 15
degrees until sluggish rpm increase disappears.
Note
Generally, a gasoline engine is sensitive to a lean
mixture compared with a glow engine, and will
stop without warning hesitation and stops with
overheating. It is recommended that the engine be
run with a slightly richer mixture.
If, on the other hand, exhaust sound is irregular
when vertically climbing from level flight, the
mixture is too rich . Land the model and close the
high speed needle approx. 15 degrees. Repeat this
procedure until the sound in level flight is steady.
If the power drops gradually or exhaust sound
weakens (overheating symptom), when performing
torque roll and hovering, the mixture is too lean.
Land the model and open the slow speed needle
approx. 15 degrees. Repeat this procedure until
power remains steady.
When the engine is started, make sure the radio
control system works normally (distance test).
Engine does not run erratic with full throttle.
Idling is stable.
Responds positively to the throttle operation.
Warm-up is finished.
FLIGHT & MAINTENANCE
Checking prior to flight
Warm-up is required as with full size aircraft and car
engines. Take off the model after warming the engine
for approx. 10 seconds with full throttle.
Precautions in flight
A slight engine rpm increase and decrease delay is
normal. Abrupt throttle operation will the cause
engine to quit. Move throttle smoothly.
Due to the construction of the carburetor, 80~90% of
maximum power develops with half throttle.
If you feel uneasy with this, adjust with transmitter
function (exponential and throttle curve, etc.) or
differential of throttle linkage.
Maintenance after the day’s flights
Please pay attention to the matter described below
to ensure that your engine serves you well in
regard to performance, reliability and long life.
Check the tightening of each screw, especially
engine installation screws and silencer installation
screws each time. Also, for the first 4 to 5 flights,
tighten the screws after each flight.
Cooling is more vitally important to a gasoline engine
than to a glow engine. If overheating symptoms (loss
of power at full throttle or exhaust note at mid speed
changes from cloudy one to clear one) are observed
during flight, immediately stop flying and carry out
the following countermeasures.
Enlarge the air intake cutout on the cowling.
Enlarge the air outlet cutout on the cowling. (It is
vitally important.)
Partly cover the air intake cutout on the cowling
where air does not hit direct the engine.
Install an air guiding plate on the fuselage and
cowling so that cooling air may be guided to the
cylinder portion of the engine and muffler.
When the interval between the flights is short and
the engine is still hot, it may be possible overheating
symptoms are observed by circulating the head from
the former flight through the engine even if the
overheating symptoms were not observed during
the former flight. In this case, leave it until the
engine is fully cooled down (in hot weather, it may
take more than one hour.) or run the engine for 4 to
5 minutes at idle.
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Fill the carburetor with fuel at the conclusion of a
day's flying. (Pay careful attention to fire and ignition
source when carrying and storing the model.)
If the engine is stored without filling the carburetor,
with fuel the inside parts will dry out and not work
properly at the next running. If the engine quits out
of fuel, refill the carburetor with fuel.
As previously mentioned, it is vitally important to
avoid operating the engine in conditions where dust,
distributed by the propeller, may be deposited on the
engine and enter its working parts.
Remember to keep your fuel container closed to
prevent foreign matter from contaminating the fuel.
Install a fuel filter to prevent foreign matter in the fuel
container from entering the fuel tank. O.S. Super
Filter (L) is available as an optional extra.
Install an in-line fuel filter between the tank and
carburetor to prevent foreign matter in the tank from
entering the carburetor.
Clean these filters periodically.
If these precautions are neglected, restrictions of
fuel flow may cause the engine to cut out, or the
fuel/air mixture to become too lean causing the
engine to overheat.
With a gasoline engine rust hardly occurs. Check
the exterior to make sure there is nothing wrong and
wipe off any oil res.
2. Start the engine. Open the throttle valve slowly
until fully open and run the engine for 10 seconds
to warm the engine.
Slow Needle Effective Range
High Needle
Effective Range
After that, tighten the silencer installation screws
every two to three flights until the gasket has been
stabilized (total 10 to 15 flights).
Starting with a Chicken stick or gloved hand
(It is suggested to use an electric starter for safety.)
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Turn on the transmitter switch.
Turn on the receiver switch.
Close the choke valve fully (ON).
Pull down the throttle stick on the transmitter fully
or to the 1/8 opened position ( 2 to 3 clicks).
Turn on the ignition switch.
Flip the propeller counterclockwise until the fuel reaches
the carburetor and you hear explosion several times.
Pull down the throttle stick fully.
Turn off the ignition switch.
Open the choke valve fully (OFF).
Flip the propeller 5 times with a chiken stick.
Tell the helper and onlookers that you will start the engine
now and have the helper hold the model securely.
Turn on the ignition switch.
Flip the propeller counterclockwise with a Chicken
stick. (Usually the engine starts with 1 to 2 flips.)
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Warning:
The engine sometimes turns to reverse rotation
though you flip the propeller counterclockwise. In this
case pull down the throttle stick fully to the end, and
turn off the igniter switch to stop the engine
immediately. If you have Throttle-Cut device in the
transmitter, use the function to stop the engine.
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