Saito FG-14B & FG-20 Owner's Operating Instruction Manual page 4

6
F G - 1 4 B / F G - 2 0 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
Engine Mounting
and Muffler
Attachment Notes
Photo is of the engine
mount for the FG-20
Mount the FG-14B or FG-20 engine on
aircraft-grade plywood with more than 6mm
thickness or to a mount of equivalent strength,
and firmly fixed, with 4 bolts. We highly
recommend the use of the included Saito
Motor Mount, SAIG1495B for the FG-14B, 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.
Figure 1
FG-14B = 14mm wrench
FG-20 = 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.
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.
F G - 1 4 B / F G - 2 0 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
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. 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.
Diameter x Pitch (inches)
Fg-14B Fg-20
13 x 8" 15 x 6–10"
14 x 6–8" 16 x 6–8"
15 x 4" 17 x 6"
3 blade 15 x7–9"
The engine produces the maximum output
when the engine is running at about 8,500–
9,200 ground rpm for the FG-14B and 8,300–
9,000 ground rpm for the FG-20.
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.
7