Saito 2008 FG-20, 2008 FG-36, FG-20, FG-36 Owner's Operating Manual
Owner’s Operating Instruction Manual
Saito™ 4-Stroke Gasoline Engines
Model FG-20 & FG-36 | Version 2008
Warning:
• Donotmodifyanypartsoftheengine
• Thisengineisdesignedforusewithradiocontrolmodelaircraft
• Incaseofmodificationsbythecustomer,HorizonHobbyInc.shallnotbearany
responsibilityfromanydamagecausedbysuchmodification
• Keeptheignitionsystemwellmaintained
™
Distributed exclusively by
Horizon Hobby, Inc., Champaign, IL 61822
www.horizonhobby.com
© 2009
SAIMAN1LG
14387
Printed 01/09
14387 SAI FG_20andFG_36 Manual.indd 26-1 12/16/08 2:09:10 PM
Introduction
Congratulations on purchasing this
fine engine.
It has been over 20 years since Saito
introduced their first 4-stroke glow
engine, the FA-30. Since that time Saito
has led the way in the development of
powerful 4-stroke glow engines, from
the small FA-30 to the large FA-325
5-cylinder radial engine. Leading the
way in innovations, we have seen the
V-twins, and now Saito is proud to
introduce the 4-stroke gasoline-powered
engine.
Saito 4-stroke gasoline engines are
developed exclusively for model
airplanes. They are designed with
an emphasis on high performance,
durability and weight savings. Their
components are modified to adapt
to the gasoline version of existing
glow engines and are equipped with a
4-stroke gasoline engine carburetor and
ignition systems.
Remember, a properly cared for
engine will offer many years of
modeling enjoyment.
Contents Included
FG-36
Engine
Engine Mount (SAIG3695)
Ignition (SAIG36153)
Muffler (SAIG3674)
Muffler Manifold (SAIG3675)
Muffler Nut, 2 pcs (SAIG3680)
Spark Plug CM-6 (SAIG36120)
Spark Plug Wrench (SAIG36969)
Valve Adjusting Tools
Muffler Wrench
Instruction Manual
Saito Decal
FG-20
Engine
Ignition (SAIG20153)
Muffler (SAIG2074)
Muffler Manifold (SAIG2075)
Muffler Nut, 2 pcs(SAIG2080)
Spark Plug 1/4-32 (SAIG20120)
Spark Plug Wrench (FG20967)
Valve Adjusting Tools
Instruction Manual
Saito Decal
Safety Precautions
This manual describes the engine and
its general operating procedures. For
mounting and control, see the
instruction manual for the model
airplane. Some suggestions are
included in this manual for mounting
the engine using the included
motor mount.
SAFETY PRECAUTIONS 1
Features of the Gasoline
4-Stroke Engine
• Fuel efficient
• Fuel cost is low
• Aircraft stays relatively clean
during operation
Table of Contents
Introduction ........................................................................................................................ 1
Contents Included ............................................................................................................. 1
Safety Precautions ............................................................................................................ 1
Engine Mounting and Muffler Attachment Notes ....................................................... 2
Throttle Linkage ................................................................................................................ 3
Propeller ............................................................................................................................. 3
Propeller and Fuel Consumption ................................................................................... 3
Fuel ...................................................................................................................................... 4
Fuel Tank and Plumbing ................................................................................................. 4
Ignition System .................................................................................................................. 4
Spark Plug ......................................................................................................................... 5
Carburetor ......................................................................................................................... 5
Preparation Before Starting the Engine ....................................................................... 6
Starting the Engine ........................................................................................................... 6
Adjustment of the Carburetor ....................................................................................... 9
General Operating Procedures ....................................................................................10
Normal Operation, Maintenance and Additional Information .............................. 10
Troubleshooting Guide .................................................................................................. 11
Engine Maintenance ...................................................................................................... 11
Valve/Tappet Gap Adjustment ..................................................................................... 12
Carburetor Maintenance .............................................................................................. 12
FG-20 Dimensions and Specifications ......................................................................... 16
FG-20 Parts List .............................................................................................................. 17
FG-36 Dimensions and Specifications ......................................................................... 18
FG-36 Parts List .............................................................................................................. 19
Full Parts List .................................................................................................................. 20
Consumer Warranty and Repair Policy ..................................................................... 22
VERY IMPORTANT
Failure to read and follow these instructions before you proceed to start your engine
may result in engine damage and the voiding of your warranty.
14387 SAI FG_20andFG_36 Manual.indd 2-1 12/16/08 2:09:10 PM
Note: For proper heat transfer, it is
important to use a metal motor mount
when mounting these engines in a model
aircraft.
• The engine is designed for use on
a model radio control airplane. If it is
used for any other purpose, we cannot
be responsible for its reliability
or safety.
• Always use genuine Saito parts
for replacements.
• Be sure to check the propeller before
each flight. If it is damaged, replace
the propeller with a new one.
• If the propeller hits something while
the engine is in operation, immediately
stop the engine and check for damage.
• Start the engine on a flat surface free
of stones or other debris.
• When mixing fuel, or operating the
engine, do so in a well-ventilated
area.
Engine Mounting
and Muffler
Attachment Notes
Mount the engine on aircraft-grade
plywood with more than 6mm thickness
for the FG-20 and 10mm of thickness
for the FG-36 or to a mount of
equivalent strength, and firmly fixed,
with 4 bolts. We highly recommend
the use of the Saito Motor Mount
(SAIG3695 for the FG-36 or SAIG2095
for the FG-20) to mount this engine to a
model aircraft.
Note: Be sure to use flat washers or a
metal plate on the reverse side of the
mount to prevent the bolts from
sinking into the plywood. Before
flying the airplane, be sure to check
for loose bolts.
Note: Since this engine is equipped with
a float less carburetor with a diaphragm
pump, the direction of the cylinder
and the position of the fuel tank can be
upright or inverted.
When you attach the muffler, use a
drop of oil on the threads to ease the
assembly. Screw the exhaust manifold
into the engine exhaust port and the
Figure 1
THROTTLE LINkAGE AND PROPELLER 32 ENGINE MOUNTING AND MUFFLER ATTACHMENT
muffler as far as the thread will allow
(see above drawing). Notice the use of
the two wrenches used in tightening
the two nuts on the muffler/manifold
connection. Use of threadlock is
recommended.
Remember to ensure cooling air passes
by the engine and muffler in a cowled
environment.
Throttle Linkage
Carefully attach the throttle linkage
to the engine using a ball link on the
carburetor throttle arm. Make sure the
linkage is free to operate from low
throttle to high throttle. Also, confirm
that the low throttle setting on the
transmitter closes the carburetor throttle
barrel to the low idle position. Adjust
the length of the pushrod until full
throttle opens the carburetor throttle
barrel to the fully open position, while
low throttle, low trim completely closes
the throttle barrel.
Propeller
Recommended Propeller Sizes:
The recommended propeller sizes
are shown in the table below. The use
of a carbon fiber propeller is highly
recommended. Remember that the use
of a large propeller will require care
in balancing it. Vibration will reduce
performance and can result in damage to
the engine and airframe.
For break-in, Saito recommends the use
of a smaller propeller for initial breakin and approximately 20 subsequent
flights.
The engine produces the maximum
output when the engine is running at
about 8,300–9,000 rpm. We would
recommend using a propeller which
makes the engine run at approximately
7,000–9,500 rpm while the airplane is
in flight.
Propeller and Fuel
Consumption
In order to decrease fuel consumption
and prolong the life of the engine,
a propeller should be selected that
maximizes rpm's when the throttle is
fully open, and an airframe that will
perform flights at about 90% of the
propeller output. If the load is large, (the
diameter and pitch of the propeller is
large) the air-fuel mixture will have to
be rich. If the load is small, the rpm’s
will be high, but the fuel consumption is
lowered because the high-speed needle
valve is closed or leaned out more.
FG-20
15 x 6-10"
16 x 6-8"
17 x 6"
3 blade 15x7-9"
Diameter x Pitch (inches)
FG-36
17 x 10-13"
18 x 8-10"
19 x 8-10"
20 x 8"
Photo is of the engine
mount for the FG-36
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Fuel
• Mix a ratio of gasoline to oil of 20:1
for break-in and continuous operation
on all engines.
• A mixture of commercial regular
gasoline and a reliable High quality
100% Synthetic oil for 2-cycle
engines must be used (we
recommend Evolution Oil,
EVOX1001Q). Unleaded high-octane
gasoline is not required for
Saito engines.
• Remember to use caution in the
storage, use and transport of gasoline.
• Since commercial gasoline has
many impurities, please be sure to use
a reliable fuel filter (SAI50109) in
your fuel system.
Note:
• Be sure to use a gasoline-resistant
type of fuel tubing (like Tygon). DO
NOT use any silicone rubber type of
fuel line to the engine or in the
fuel tank.
• The use of fuel with up to 10%
ethanol has been tested and found to
work fine.
Fuel Tank and
Plumbing
Be sure to include a reliable fuel filter
in your fuel system. The drawing above
suggests use of a fuel feed line and an
air intake line. Also, be sure to use a fuel
line compatible with gasoline.
IMPORTANT: Air is necessary to cool
the engine during operation. Make sure
that sufficient air circulation through
the cowling is provided. As a basic
reference, the outlet area should be 3
to 5 times the area of the inlet area to
provide adequate cooling.
Ignition System
Saito gasoline four-stroke engines
come with Saito’s own ignition system
composed of the ignition unit, cord for
sensor (black and white), cord for earth
to ground (green) insulated plug cap,
and cord (black and red) for connection
to a battery (not included). You will also
need to secure an on/off switch (safety
switch system). The switch must be
SPARk PLUG AND CARBURETOR 54 FUEL AND IGNITION SYSTEM
Figure 2
capacity of more than 1,000mA. Be
sure to mount the ignition system in a
location near the engine and away from
the receiver to prevent any unwanted
interference. Please refer to the
diagram below.
Spark Plug
NGK-CM6 (SAIG36120) is the
standard-equipped plug with the FG-36.
The FG-20 comes with Saito's own
1/4-32 spark plug (SAIG20120). When
needed, please replace with identical
appropriate plugs.
Carburetor
The carburetor used on gasoline fourstroke engines are exclusive to Saito.
Since they have a negative pressure type
fuel pump, the engine can be mounted in
any position.
CAUTION: If fuel remains in the
carburetor after flight, the components
made from rubber, such as the
diaphragm, will deteriorate over time.
After a flying session, it is best to
remove any fuel remaining in the carburetor by disconnecting the fuel line and
Figure 4
NGK-CM6
Spark gap = .7-.8mm (.024 - .028 in)
1/4-32
Spark gap = .4 - .5mm (.016 - .020 in)
Figure 3
14387 SAI FG_20andFG_36 Manual.indd 4-5 12/16/08 2:09:12 PM
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
STARTING THE ENGINE 76 BEFORE STARTING THE ENGINE
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
High-Speed Needle Valve
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
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