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Saito FG-84R3 Operating Instructions Manual Page 4

4-stroke gasoline radial engine.
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8. Engine mounting, muffler attachment, and breather waste disposal
FG-84R3 can be installed with mount spacers. As the carb comes out from back of the firewall,
hollow out the firewall as possible as minimum referring to the cutting sheet included.
Make the firewall robust enough because this part has to endure vibration and torque caused by
prop rotation. Especially with a low load prop, engine tend to generate large vibration that is
very dangerous.
It is preferable to apply some adhesives (such as screw lock) on the tip of each cap screw to
avoid looseness when you install the engine.
To ensure that cooling wind passes through the engine, the cowling should be devised. Also
make the air flow outlet larger than the inlet.
Building some baffles inside the cowling to flow the cool air through the surface of the engine
effectively that is highly recommended. Insufficient cooling may cause engine trouble such as
overheat, percolation, or muffler looseness.
The mufflers should be securely inserted deeply into the cylinder and tightened up using
spanners. (Adhesives, such as a screw lock agent, are effective against looseness and leakage.)
Make sure to fix the outlet of the flexible mufflers outside of the cowling using the bracket
included. (Regarding muffler installation, please refer to the attached document.)
For breather treatment, there is also a method in which the aluminum pipe, etc. are fixed at the
muffler outlet to diffuse the hot air together with exhaust gas into the air. (Breather may
function by simply ejecting the tube from the engine).
9. Preparation for engine start (assuming break-in)
(1) Mount the engine on a robust and parallelized test bench or on the fuselage. (Either way, the
engine should be fixed and immobile.)
(2) Check whether the throttle valve becomes fully closed and opened certainly.
(3) Check whether each code of the ignition system is connected certainly.
(4) Use about 1000cc tank for the test bench, or a tank which has appropriate capacity for the fuselage.
(5) For piping, only connecting the carburetor with the tank is needed.(Make sure there's no leakage at
all the connections.) In order to check discharge of the breather, attach a heat-proof and gasoline-
proof transparent tube to the breather nipple.
(6) For fuel, prepare a mixed gasoline with a volume ratio of gasoline : oil = 15 20 : 1 .
(7) Prepare a well balanced 24 x 10 carbon-made prop (Mejzlik is recommended).
 *Prop attaching position
 Since SAITO 4-stroke gas-engine can be manually started in forward direction of the rotation, fix the
prop in the position which facilitates vigorous cranking.
(8) When starting with an electric starter, also attach a spinner. (This way of start is recommended for
(9) As it is difficult to judge clearly the peak condition of 4-stroke engines, prepare a tachometer to
prevent over-throttling or overheat. You can also use digital tachometer (Option).
(10) Prepare a fuel pump for gasoline. (Be sure to attach a filter to the intake port. It is available as an option.)
Caution: If there s anyone stand in front of the engine, be sure to have them move behind the airplane before starting the
engine. Also keep in mind that the exhaust smoke is harmful for health. Keep away one of your arm holding the airplane
away from the prop. Once the engine starts, move behind the airplane. Make needle adjustment or other control from rear. If
the airplane cannot be fixed, ask your assistant to hold the airplane for safety.
10. Method of starting the engine
The following is the procedure with the engine mounted on the airplane. Fill up the tank with fuel.
(Be sure to turn off the switch of the ignition system until just before trying to start up the engine.)
(A) Starting method with a starter (Recommended)
(1) After confirm that the throttle stick is located at the full-close position, turn on the transmitter switch. Then turn on the receiver
switch to check throttle valve and other operation. After that, fully close the throttle valve.
(2) Power on the ignition system.
(3) Open the throttle valve about 1/4 from the full close position by using the throttle stick. (Starting with excessively opened
throttle is dangerous since the airplane jumps forward.)
(4) Apply the starter to the prop and activate for about 5 seconds to start the engine.
(B) Manual starting method (For safety, wear gloves and use a safety stick)
(1) Same as (1) noted above. (The throttle valve must be fully closed. Otherwise, the fuel cannot be manually introduced.)
(2) Make sure to turn off the ignition switch.
(3) Following Chapter 7, perform choking method. ( Choking - Ignition ON - Throttle 1/4 open - Flick )
11. Break-in
(Referring Fig.10, check in advance where the Main needle and Slow needle are placed.)
As Break-in is an important procedure to pull out the maximum performance of the engine, it must be cautiously done.
The purpose of break-in is initial lubrication and adjusting of the mobile parts under the condition with rich fuel mixture.
Never make the fuel mixture lean. Lean fuel mixture could cause seizure even during idling or low speed running.
There s no need to adjust the slow needle at this step as it s already set adequately, so you will adjust only the main needle
during break-in.
(1) After filling up the fuel tank, start the engine as described in the above Chapter 10 and run it for 10 sec in low speed.
(2) Open the main needle 2 turns from that state and use the throttle stick to fully open the throttle valve. If rich air-fuel
mixture can t be obtained, open the main needle additionally. Then continue running for more than 1 tank.
During this initial operation, contact of each part inside the engine will be matched. So make the fuel mixture rich as much
as the engine doesn t stop. Do not care about running smoothness at this step.
Mount spacer
Hollow out
minimum area
Cool air
Muffler outlet
Aluminum pipe
Breather nipple


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