Saito FA-120 Special Instruction Manual page 5

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S T A R T I N G T H E E N G I N E
• Connect the heating source to the
glow plug.
• Using either the "Start Stick
(HAN113)" or electric starter, spin
the propeller until the engine is
running.
Note: A very common error is to
remove the glow plug igniter too early.
It is suggested that the igniter be left
attached until after the engine has been
run up and the high-speed needle valve
has been properly adjusted.
8. Initial break-in:
Do not exceed 4,000 rpm for the first
10 minutes of operation. This allows
all parts to mate properly with good
lubrication.
Note: Due to the excessively "rich"
mixture setting, it may be necessary to
leave the heat source attached to the
glow plug.
Subsequent runs may be made while
slightly leaning out the mixture with
each tank full of fuel. Forty minutes is
considered sufficient time for normal
break-in prior to the first flight.
9. After break-in:
If a test stand was used for the break-
in procedure, the engine may now be
mounted in the aircraft using a high-
quality motor mount such as those
available from Saito ™ specifically or
for Saito engines.
The idle needle valve (89) may now be
refined. Please refer to the "Carburetor
Adjustments" section shown below for
information on how to do so.
The valves may also be checked
at this time. Refer to the "Engine
Maintenance" section on page 8–9
for information on the valve/tappet
adjustments.
The use of a tachometer is encouraged
for setting the high-speed needle valve
(85) prior to flight. The peak rpm
should be obtained and then reduced
by approximately 200 – 300 rpm by
turning the high-speed needle valve
counter-clockwise (richen). Each
engine's peak rpm can be found on the
"Propeller Chart" on page 14. Over-
revving of a 4-stroke engine can cause
internal damage to the engine.
Carburetor
Adjustments for Two-
Needle Carburetors
The low-speed, or idle needle valve
(89), is preadjusted at the factory for
best performance during break-in.
After break-in it may be necessary to
"fine tune" the low speed adjustment
using the following procedure:
1. Start the engine and let it warm up
prior to attempting any adjustments.
2. Close the throttle slowly and adjust
the low speed setting by rotating the
idle needle valve (89) clockwise to lean
the mixture and counterclockwise to
richen the mixture.
Note: The fuel mixture is too rich
if, when opening the throttle rapidly,
the engine emits white smoke and
"stutters" or "stumbles." Correct
this by rotating the idle needle valve
clockwise 1/4 to 1/2 turn at a time
until the engine transitions smoothly
without hesitation upon opening the
throttle rapidly.
The fuel mixture may be too lean if the
engine stops at the lowest idle position,
or when the throttle is rapidly opened
from idle. Attempt to correct this by
rotating the idle needle valve counter-
clockwise 1/4 to 1/2 turn at a time until
the engine transitions smoothly without
hesitation upon opening the throttle
rapidly. If the situation is not rectified
by counterclockwise rotations of the
idle needle valve, turn the idle
needle valve clockwise in 1/4 to 1/2
turn increments.
3. After obtaining the proper idle
setting, the low rpm setting may be
made through the positioning of the
throttle adjustment screw, if applicable.
If not, adjust the idle setting via the
throttle trim of your transmitter.
C A R B U R E T O R A D J U S T M E N T S
Normal Engine
Operation
If break-in was accomplished on a test
bench, your engine may be mounted to
the aircraft and flown. The initial flight
should be performed with the engine
adjusted for a rich fuel mixture.
1. Your Saito ™ engine should be
securely mounted to the aircraft. There
are many motor mounts available;
however, a high-quality metal mount,
such as those manufactured by Saito
exclusively for Saito engines, is
considered to be the best.
2. General operating procedures that
will ensure long engine life are:
• Do not operate the engine with a
"lean" mixture.
• Regularly check all screws and nuts
on both the engine and muffler.
• After 1 to 2 hours of operation, valve
adjustment may be necessary. Adjust
the valves as shown in the "Engine
Maintenance" section.
• The Saito engines are equipped
with a breather nipple (19). It is
recommended that a length of
silicone tubing be attached to this
crankcase breather nipple (19)
and routed away from the engine
compartment so the excess oil can be
expelled outside of the aircraft.
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