Counter-clockwise direction
(for rich mixture)
Clockwise direction
(for lean mixture)
Clockwise direction
(for lean mixture)
Counter-clockwise direction
(for rich mixture)
High-Speed Needle Valve
Low-Speed Needle Valve
Ball-joint for linkage
Throttle lever
sure that the spark plug is screwed in
and tightened, and that the plug socket
cap is fitted in place and fastened down
properly. Fix the ignition sensor in the
proper position at the bottom of the
engine crankcase. The throttle servo
should be mounted at a distance of 8 to
12 inches from the engine. The spark
plug cable must not touch any part of
the model structure as vibration may
damage the shielded cable. If this is not
practical, it will be necessary to provide
an insulation material for the cable. The
ignition unit itself should be wrapped
in foam rubber to prevent engine
vibration from damaging the electronic
components. All components must be
protected from contact with engine
fuel. Be sure to use an on/off (Safety or
“kill”) switch to allow the ignition to be
turned off and on.
IMPORTANT:
Never turn the engine
over with the ignition turned on unless
the spark plug is inserted in the plug
socket. This could lead to ignition
damage.
Note:
Saito 4-stroke gasoline engines
come with a pumped carburetor. You
do not have to choke the engine as you
normally would a 2-stroke engine.
When you are ready to start the engine,
switch the ignition on and set the throttle
to a slightly high idle speed. We highly
recommend the use of an electric starter.
Be sure to have a helper hold the model
securely.
a. Turn on the transmitter first, then the
receiver and check the operation of the
throttle servo and other controls.
b. Turn on power to the ignition system.
c. Using an electric starter, begin
cranking the engine. It should fire within
seconds of applying the starter. Allow
the engine to idle for 30 to 45 seconds.
d. If the engine does not start, even after
using the electric starter to crank the
engine a second time, open the throttle
to maximum, turn off the ignition and
turn the engine over about 4 revolutions.
Switch the ignition on again and then
restart the engine with the throttle at a
fast idle position.
e. If the engine still will not start,
unscrew the spark plug and check its
Figure 5
S T A R T I N G T H E E N G I N E
7
6
B E F O R E S T A R T I N G T H E E N G I N E
rated to a minimum 3A.
Saito recommends the use of a battery
with a voltage of 4.8V to 6V and
running the engine until it is dry.
Do not needlessly disassemble the
carburetor. If you experience problems
with the carburetor, return it to the Saito
Horizon Service Center.
Preparation Before
Starting the Engine
(prior to break-in)
• Mount the engine on a strong, flat test
bench or on the aircraft. (In either
case, the engine should be secured so
it is immobile.)
• Check to make sure the throttle
barrel will open and
close completely.
• Check the wiring of the ignition
system to make sure it is connected
correctly and securely.
• Make sure the fuel line is connected
securely to the carburetor.
• For break-in, use a fuel/oil mix ratio
of 20:1.
• FG-36: Mount an 18x8 or 19x8
carbon fiber propeller such as
a Bolly or Mejzlik. Be sure it has
been balanced. (Remember to check
the tightness after every flight.)
• FG-20: Mount a 15x6 plastic or
wood propeller. Be sure it has
been balanced. (Remember to check
the tightness after every flight.)
• It is suggested you employ a
spinner when using an electric
starter. (Remember to check the
tightness after every flight.)
• Use a tachometer to prevent over-
revving of the engine.
• Be sure to connect a gasoline-proof
line to the breather nipple to vent oil
from the airframe.
• Check the battery of the electric
starter to make sure it is fully
charged. Be sure to use a safety
on/off switch from the battery
to the ignition.
WARNING:
Do not let people stand
in front of or to the side of the engine
while attempting to start it. Also, make
sure the engine test bench or aircraft is
completely secure from movement.
Starting the Engine
(assuming the engine is mounted
in an aircraft)
Saito’s carburetors come adjusted to
a basic setting. This setting should be
maintained during the initial break-in
runs. The standard carburetor settings
are as follows: The high-speed needle
valve is set to about 2 1/3 turns from
the fully closed position. The low speed
or idle needle valve is set to about 4
turns out from the fully closed position.
Please refer to the diagrams on the next
page.
Before you first start the engine, make
Low-Speed Needle Valve
High-Speed Needle Valve
Counter-clockwise direction
(for rich mixture)
Clockwise direction
(for lean mixture)
Counter-clockwise direction
(for rich mixture)
Clockwise direction
(for lean mixture)
Low-Speed Needle Valve
High-Speed Needle Valve
Counter-clockwise direction
(for rich mixture)
Clockwise direction
(for lean mixture)
Counter-clockwise direction
(for rich mixture)
Clockwise direction
(for lean mixture)
Figure 6
FG-20 CARB
FG-36 CARB
14387 SAI FG_20andFG_36 Manual.indd 6-7
12/16/08 2:09:13 PM
