Saito FG-14C, FG-17, FG-21, FG-30B, FG-36B Owner's Operating Instruction Manual

Owner’s Operating Instruction Manual

Saito™ 4-Stroke Gasoline Engines

Model FG-14C, FG-17 & FG-21
Model FG-30B, FG-36B & FG-40

Version 2012

2

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.

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.

NOTICE

All instructions, warranties and other collateral documents are subject to change at the sole discretion of
Horizon Hobby, Inc. For up-to-date product literature, visit horizonhobby.com and click on the support tab for
this product.

Meaning of Special Language

The following terms are used throughout the product literature to indicate various levels of potential harm when
operating this product:

NOTICE: Procedures, which if not properly followed, create a possibility of physical property damage AND a
little or no possibility of injury.

CAUTION: Procedures, which if not properly followed, create the probability of physical property damage AND
a possibility of serious injury.

WARNING: Procedures, which if not properly followed, create the probability of property damage, collateral
damage, and serious injury OR create a high probability of superficial injury.

WARNING: Read the ENTIRE instruction manual to become familiar with the features of the product
before operating. Failure to operate the product correctly can result in damage to the product, personal
property and cause serious injury.

This is a sophisticated hobby product. It must be operated with caution and common sense and requires some
basic mechanical ability. Failure to operate this Product in a safe and responsible manner could result in injury
or damage to the product or other property. This product is not intended for use by children without direct adult
supervision. Do not attempt disassembly, use with incompatible components or augment product in any way
without the approval of Horizon Hobby, Inc. This manual contains instructions for safety, operation and mainte­nance. It is essential to read and follow all the instructions and warnings in the manual, prior to assembly, setup
or use, in order to operate correctly and avoid damage or serious injury.

Age Recommendation: Not for children under 14 years. This is not a toy.

Safety Warnings and Precautions

3

• Never return unused fuel from the fuel tank back into
the fuel container.

• Never attempt to repair or modify a propeller beyond
its intended use.

• Never handle model engines, mufflers and/or tuned
pipes until they have had time to cool. They become
extremely hot when in use.

• Never use hands, fingers, or any other body part to
stop the propeller.

• Never throw any object into a propeller to stop it.

• Never run the engine in the vicinity of loose small

objects, such as gravel or sand, to avoid the propeller
uncontrollably throwing such materials.

• Never wear loose clothing or a loose neckstrap when
operating your model engine as these items could
become entangled in the propeller.

• Never have loose objects such as screwdrivers,
pencils etc. in your pockets when operating your
model engine. These could fall into the propeller.

• Never allow fuel to come into contact with eyes
or mouth. Gasoline and other fuels used in model
engines are poisonous.

• Always ensure spectators, especially children, are at
least 30 feet away when running the engine.

• Always ensure that the propeller is securely attached
to the engine shaft and all retaining fasteners are
tightened properly before EACH flight. Use of blue
threadlock to tighten nuts is advisable.

• Always keep small parts out of the reach of children
as they can be choking hazards.

• Always secure the airplane before powering the
engine.

• Always keep your face and body away from the path
of the propeller blades when starting or running your
engine.

• Always stand behind the propeller when making
carburetor adjustments.

• Always wear safety glasses or goggles when starting
and running your engine.

• Always keep your fuel in a safe place well away from
sparks, heat or anything that can ignite.

• Always ensure the aircraft is secure and will not
move once the engine is started.

• Always rebind your transmitter to your receiver(s)
after setup and before first flight.

• Always ensure the throttle failsafe is set to low
throttle in your transmitter.

• Always perform a range check prior to flight.

• Always cut off the fuel supply (pinch or disconnect

the fuel line to the carburetor) or use the throttle
linkage to shut off the air in order to stop the engine.

• Always ensure gasoline and fuel is stored in a
clearly marked container well away from the reach
of children.

• Always mount the engine securely on a bench mount
or high-quality engine mount.

• Always use the correct size and pitch of propeller for
your engine. Refer to Propeller Chart in this manual.

• Always confirm proper balance of your propeller prior
to installation of the engine. Failure to do so could
cause damage to the engine and/or the airframe.

• Always utilize an electric starter to start your engine.

• Always discard any propeller that is nicked,

scratched, cracked or damaged in any way.

• Always run your model engine in a well-ventilated
area. Model engines produce possibly harmful
carbon monoxide fumes.

• Always store your fuel safely in a sealed, water­resistant container.

• Always store fuel in a cool, dry location. Do not
allow fuel containers to come in direct contact with
concrete, as the fuel may absorb moisture.

• Always responsibly discard fuel if there is
condensation and/or water inside the fuel container.

Model engines produce a substantial amount of power and can create unsafe situations if not used correctly.
Always use common sense and observe all safety precautions when operating, handling or performing any
procedure involving your engine. Failure to follow safety precautions could result in serious injury and property
damage.

4

Table of Contents

Safety Warnings and Precautions ..........................................................2

Introduction to the Saito Gasoline 4-Stroke Engines .............................................4

Components .........................................................................5

FG-14C/FG-17/FG-21 Engine Instructions .................................................5

Engine Mounting and Muffler Attachment ...................................................5

Propeller ........................................................................... 6

Fuel ..............................................................................7

Fuel Tank and Plumbing ................................................................7

Spark Plug .........................................................................8

Carburetor .........................................................................8

Preparation Before Starting the Engine (prior to break-in) ........................................ 9

Starting the Engine (assuming the engine is mounted in an aircraft) ...............................10

Break-in ..........................................................................11

General Operating Procedures (to ensure the long life of the engine) ..............................11

Normal Operation, Maintenance and Additional Information .....................................12

Setting the Needle Valves in the Gas 4-Stroke Engines ........................................12

FG-30B/FG-36B/FG-40 Engine Instructions ............................................... 13

Engine Mounting and Muffler Attachment ..................................................13

Propeller .......................................................................... 14

Fuel .............................................................................15

Fuel Tank and Plumbing ...............................................................15

Carburetor ........................................................................16

Preparation Before Starting the Engine (prior to break-in) ....................................... 17

Starting the Engine (assuming the engine is mounted in an aircraft) ...............................17

Choking the Engine ..................................................................18

Running-In the Engine ................................................................18

Final Adjustment of the Carburetor .......................................................19

Troubleshooting Guide ................................................................19

Carburetor Maintenance ..............................................................20

Valve/Tappet Gap Adjustment ........................................................... 20

FG-14C/FG-17/FG-21 Dimensions, Specifications, Parts List and Exploded View .......................21

FG-30B/FG-36B/F-40 Dimensions, Specifications, Parts List and Exploded View .......................25

Warranty Information ..................................................................33

Introduction to the Saito™ Gasoline 4-Stroke Engines

The Saito four-stroke gasoline series of engines were developed to satisfy a market need for a more cost-effective
and cleaner answer to the then current glow-powered engines. Ever at the forefront of technology, Saito has led
the way many times in developing engines with large displacements in small case sizes. It seemed only natural
that they would also lead the way to a more cost-effective fuel alternative to glow-powered engines.

5

FG-14C FG-17 FG-21 FG-30B FG-36B FG-40

Engine

3 3 3 3 3 3

Valve Adjusting
Tools

3 3 3 3 3 3

Muffler Wrench

3 3 3

Ignition SAIG14C153 SAIG17153 SAIG17153 SAIG30B153 SAIG30B153 SAIG40153

Engine Mount SAIG1495 SAI10095 SAIG2095 SAIG3095/

SAIG3695

SAIG3095/
SAIG3695

SAIG3695

Spark Plug 1/4-32;

SAIG20120

1/4-32;
SAIG20120

1/4-32;
SAIG20120

CM-6;
SAIG36120

CM-6;
SAIG36120

CM-6;
SAIG36120

Muffler SAIG1474 SAIG1474 SAIG2074 SAIG3674 SAIG3674 SAIG3674

Muffler
Manifold

SAIG8075B SAI91S75 SAI125A75 SAI120S75A/

SAIG3675

SAI120S75A/
SAIG3675

SAIG3680

Muffler Nut,
2 Pcs

SAIG8080A SAIG8080A SAI125A80 SAI120S80/

SAIG3680

SAI120S80/
SAIG3680

SAIG3680

Spark Plug
Wrench

SAIG20967 SAIG20967 SAIG20967 SAIG36969 SAIG36969 SAIG36969

Components

Engine mount for the FG-21

Mount the FG-14C, FG-17 or FG-21 engine on aircraft­grade plywood with more than 6mm thickness or to
a mount of equivalent strength, then firmly fix with 4
bolts. We highly recommend the use of the included
Saito Motor Mount for the FG-14C (SAIG1495B), FG-17
(SAI10095) or FG-21 (SAIG2095) to mount this engine
to a model aircraft.

NOTICE: 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.

Since this engine is equipped with a floatless carburetor
with a diaphragm pump, the direction of the cylinder in
regards to the position of the fuel tank can be upright
or inverted.

FG-14C/FG-17/FG-21 Engine Instructions

Engine Mounting and Muffler Attachment

6

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 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 and low throttle, low trim completely closes the
throttle barrel.

Throttle Linkage

Propeller

Recommended Propeller Sizes: The recommended
propeller sizes are shown in the table below. 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 the initial break-in and approximately 20
subsequent flights.

Diameter x Pitch (inches)

FG-14C FG-17 FG-21

13 x 8 14 x8 15 x 6–10

14 x 6–8 15 x 6–8 16 x 6–8

15 x 4 16 x 6 17 x 6

3 blade 15 x 7–9

The engine produces the maximum output when the
engine is running at about 8,500–9,200 ground rpm
for the FG-14C and 8,300–9,000 ground rpm for the
FG-17/FG-21.

Propeller and Fuel Consumption

In order to decrease fuel consumption and prolong the life of the engine, choose a propeller that maximizes rpm when
the throttle is fully open, and an airframe that performs 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
will be high, but the fuel consumption is less due to the high-speed needle valve being leaned out more.

Figure 1

FG-14C = 14mm wrench
FG-21 = 17mm wrench

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 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.

NOTICE: Air is necessary to cool the engine during
operation. Make sure 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.

7

Fuel

• Mix a ratio of gasoline to oil of 20:1 for break-in and

continuous operation on all engines.

• A mixture of high-quality 91 octane unleaded

gasoline and a reliable, high-quality 100% synthetic
oil for 2-cycle engines must be used. We recommend
Evolution Oil (EVOX1001Q).

With the use of an oil mixture of 20:1, it is normal to
see a slight amount of carbon buildup on the exhaust
valve itself. This is why it is important that you use a
high-quality synthetic oil instead of standard 2-stroke
oil you may be using in your 2-stroke gas engine.
Although these 2-stroke oils work well in their intended
applications, they can cause a build up of a gummy
residue on the exhaust valve in a 4-stroke gas engine.
This may require service for your engine if the exhaust
valve begins to stick and not seal properly.

The high-quality Evolution oil we recommend will still
build up a slight amount of carbon, but we have found
that this build up is easily flaked off during normal
operation of the engine. It will not create the typical
gummy build up.

• 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
or HAN143) in your fuel system.

• The recommended fuel tubing is Evolution

®

Gasoline
Fuel Tubing (EVOA102). DO NOT use a silicone
rubber fuel line for the engine, the fuel tank, or your
fueling system.

• The use of fuel with up to 10% ethanol has been
tested and found to work fine.

• The use of a filtered clunk or sintered clunk on the
fuel pick up line is required. The Evolution In-tank
Felt Filter/Clunk (EVOA106) is designed specifically
for gas engine operation.

Figure 2

Figure 3

Filtered Weight

Gasoline-resistant Rubber Cap

Fuel Tank

Vent Tube

Fueling Tube

Gasoline-resistant Tube

Gasoline-resistant Tube

Carb Nipple

Fuel Filter

Be sure to include a reliable fuel filter in
your fuel system. The drawing to the left
suggests the use of a fuel feed line and
an air intake line. Also, be sure to use a
fuel line that is compatible with gasoline.

Fuel Tank and Plumbing

8

Saito gasoline four-stroke engines come with the Saito
ignition system, composed of the ignition unit, a cord
for the sensor (black and white), 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 carry a rating
of 3 amps.

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.

The Saito ignition has an operating voltage from

4.8–9.0 volts. Saito recommends the use of a 5-cell

Ni-Cd/Ni-MH battery or a 2-cell Li-Po/Li-Ion/Li-Fe with
a minimum of 1000mAh. The recommended battery is
the Team Orion

®

Avionics Li-Fe Receiver Pack 1300mAh

6.6V (ORI60503).

1/4-32
Spark gap = .4 to .5mm (.016 to .020 in)

The FG-14C, FG-17 and FG-21 come with the Saito
1/4-32 spark plug (SAIG20120). When needed,
replace with identical plugs.

Ignition System

Spark Plug

Carburetor

The carburetors used on gasoline four-stroke engines
are exclusive to Saito. Since they have a negative
pressure type fuel pump, the engine can be mounted in
any position.

NOTICE: Always remove fuel from the carburetor
after flight. Not doing so will result in rubber engine
components (such as the diaphragm) deteriorating
over time, causing loss of engine performance.

After a flying session, it is best to remove any fuel
remaining in the carburetor by disconnecting the fuel
line 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.

Cord for plug (mesh)

Plug cap

Sensor

Battery

Cord for
ignition sensor

Cord for
Tachometer display

Cord for battery

Switch (capacity
more than 3A)

Unit

Battery

Voltage [6–8.4V]

Capacity: more than 1,000mA

Figure 4

9

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 carburetor 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-14C: Mount a 14 x 6 plastic or wood propeller.

Be sure it has been balanced. Check the tightness
after every flight.

• FG-17: Mount a 14 x 8 plastic or wood propeller. Be
sure it has been balanced. Check the tightness after
every flight.

• FG-21: Mount a 15 x 6 plastic or wood propeller. Be
sure it has been balanced. Check the tightness after
every flight.

• It is suggested you employ a spinner when using an
electric starter. Check the tightness after every flight.

• Use a tachometer to determine proper needle valve
settings 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: Always keep all spectators,
especially children, are at least 30 feet away
when running or starting the engine.

WARNING: Always ensure the aircraft is
secure and cannot move when preparing to
start the engine. Failure to do so could cause
property damage and serious injury.

To best understand the FG-14C, FG-17 and FG-21
carburetor, you need to know what it is not.

It is not a Walbro carburetor.
It is not a glow carburetor.

As we made strides to bring cheaper gasoline power to
ever smaller engines, this uniquely designed carb was
developed because the currently available carbs from
the lawn power equipment world were way too large to
be included with our smaller powerplants.

Gasoline fuel requires a much finer atomization of the
droplets than glow fuel does. Because the amount of
fuel flowing through the engine is so much lower than
with a typical glow fuel setup (up to 60% less fuel),
maintaining a constant flow and pressure becomes even
more critical. Close inspection of the cat’s eye orifice on
the needle valve body in the FG-14C/21 carb reveals
a miniscule opening; perfectly sized for the proper
atomization of the fuel for your engine.

This new carb features a pump function designed to
provide the correct amount of fuel to the needle valve
assemblies to correctly operate the engines. It is not
designed as a fuel pump to draw fuel from a tank
mounted in the middle of your airplane. The fuel tank
needs to be mounted as close to the centerline of the
Carb assembly as possible; the same as we have had to
do for all these years with our glow engine installations.
If you stray very far from this rule, the engine will run
differently upright and inverted. This usually leads to
comments that an engine doesn’t like to run inverted,
etc., when in reality, the fuel delivery system needs to be
optimized for the engine installation being used.

The pump is actuated by the negative pressure pulses
when the intake valves are open and the engine is
drawing fuel into the cylinder. On the latest version
of the carburetor, we enlarged the area of the hole
that delivers these pulses to the pump assembly. It
has greatly improved the pumping action and has
much more tolerance of ‘less than optimum’ fuel tank
locations. But it is still not a Walbro carb and will not
draw fuel from any long distance.

Understanding the Saito Gas Carb for the FG-14C, FG-17 and FG-21

10

The carburetor on the Saito engine comes with the
low-speed needle adjusted to a basic setting. The
high-speed needle will need to be set by the user. The
standard carburetor settings are as follows: The high­speed needle valve is set open counterclockwise from
the fully closed position.

On the FG-14C, FG-17 and FG-21 the low-speed needle
should be set at 7-5/8 from closed.

1. Disconnect the throttle arm from the throttle pushrod.

2. Manually hold the throttle barrel closed.

3. With a small tip flat screwdriver, screw in the idle
adjustment all the way until you feel the throttle
barrel trying to rotate. The low-speed adjustment
is actually not a needle—it is a sleeve that cover/
uncovers a cat’s eye slit in the fuel supply tube.
When you run the low-speed adjustment all the way
in, the sleeve will bottom out against the fixed carb
body and force the barrel to rotate.

4. Now richen the low-speed needle by 7 turns, 35
minutes. In our experience, this will be within an 1/8
of a turn (+/–) from perfect at the low end.

5. Reconnect the throttle pushrod.

6. Once this change is made to the low end, open the
high end by 1/2 turn from where you ran it before,
restart the engine and reset the high-end needle
valve. Please refer to the diagrams.

The minutes listed are in reference to the minute hand
of a clock.

FG-14C FG-17 FG-21

High-speed
needle

1 turn
20 minutes

1 turn
30 minutes

1 turn
30 minutes

Low-speed
needle

7 turns
35 minutes

7 turns
35 minutes

7 turns
35 minutes

Before you first start the engine, make sure 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.

Figure 5—FG-14C/FG-17/FG-21 Carburetor

NOTICE: 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.

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.

Starting the Engine (assuming the engine is mounted in an aircraft)

11

Be sure to have a helper hold the model securely.

• Turn on the transmitter first, then the receiver and
check the operation of the throttle servo and other
controls.

• Turn on the power to the ignition system.

• 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.

• 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.

• If the engine still will not start, unscrew the spark
plug and check its contacts. Clean any possible
excess fuel (an indication of engine flooding) and
screw it in again. Further starting should only be
done with the throttle at idle position. If the plug is
dry, probably not enough fuel has been drawn into
the carburetor. If that is the case, check the fuel feed
and then return to the instructions above.

We strongly urge the use of a tachometer to check rpm
readings when breaking in the engine.

After starting and warming the engine for 30 to 45
seconds, adjust as follows: for initial break-in, do not
exceed 4,000 rpm for the first 10 minutes of operation.
This allows all the parts to mate properly with good
lubrication.

WARNING: Before adjusting the carburetor,
you MUST stop the engine. Failure to do so
will cause the propeller to continue to move if
the engine is not stopped, which could result
in serious injury.

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.

Conrods

Saito has developed a specific aluminum alloy and manufacturing process that allows them to eliminate the need
for a separate bearing material in the lower end of their conrods. The benefit of this is you never have to worry about
the bearing material (usually bronze oilite) rotating in the conrod and blocking off the critical bearing lubrication
holes machined into the bottom of the conrod. This process also allows for smaller crankcases and smaller airplane
applications. It also creates the requirement for the 20:1 oil mixture in our gasoline powered engines.

Do not skip this step. You risk seizing the conrod to the crankshaft.

The most important component to break-in on all Saito 4-stroke engines, and especially the gasoline engines, is
the conrod to crankshaft interface. The break-in process required for all Saito engines is designed to break-in the
conrod to crankshaft interface more than to seat the ring. The ring will seat gradually over time and the engine will
develop more and more power. Ensure the conrod is treated correctly from the beginning.

Break-in

• Do not operate the engine with a “lean” mixture.

• Regularly check all screws and nuts on both the engine and muffler.

• After every 1 to 2 hours of operation, valve adjustment may be necessary. Adjust the valves as shown in the

Engine Maintenance and Valve/Tappet Adjustment Sections.

• Saito engines are equipped with a “breather” nipple. It is recommended that a length of PFM type tubing
(EVOA102) tubing be attached to this crankcase breather nipple and routed away from the engine compartment
so the excess oil can be expelled outside of the aircraft.

General Operating Procedures (to ensure the long life of the engine)