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
T H R O T T L E L I N k A G E A N D P R O P E L L E R
3
2
E N G I N E M O U N T I N G A N D M U F F L E R A T T A C H M E N T
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 break-
in 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
14387 SAI FG_20andFG_36 Manual.indd 2-3
12/16/08 2:09:12 PM
