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Saito FG-21 Instructions Manual Page 5

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(10) Prepare a fuel pump for gasoline. (Be sure to attach a filter to the intake port. It is available as an option.)
(11) In order to check discharge of the breather, attach a heat-proof and gasoline-proof transparent tube.
(12) Prepare a battery for the electric starter.
Caution: If there's anyone stands forward, be sure to have them move behind the airplane prior to start 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. On starting the engine,
move to the rear of the airplane. Make needle adjustment or other control from the 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 using an electric starter for the engine mounted on the airplane.
(1) Fill up the tank with fuel. (Be sure to turn off the switch of the ignition system during filling up the fuel.)
(2) 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.
(3) Open the main needle to 1+1/2 ~2 turns or so. (This value is not the peak value.)
(4) Power on the ignition system.
(5) 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.)
(6) Apply the starter to the prop and activate for about 5 seconds to start the engine.
11. Break-in
As Break-in is an important procedure to pull out the maximum performance of the engine, it must be cautiously implemented.
The purpose of break-in is initial lubrication and adjusting of mobile parts under the condition with rich fuel mixture.
Never make the fuel mixture lean. Lean fuel mixture could cause seizure even if the engine drops to idling and runs at low speed.
(1) After filling up the fuel tank, start the engine as described in the above section "10" and operate it at a low speed in the condition for
about 5 seconds.
(2) Next, in the condition of (1), fully open the throttle valve, turn back the main needle to make the air-fuel mixture very rich in the
range where the engine does not stall (5,000 rpm or less). Operate in this condition with 2 (or more) tanks. (Conduct this step
checking the density of the exhaust and the breather' waste oil (inky-black waste oil)).
(3) Next, after filling up the tank, re-start the engine. With the throttle valve fully opened, throttle the main needle and operate the
engine for one tank at 7500 – 8,000 rpm.
(4) Next, after filling up the tank, re-start the engine. With the throttle valve fully opened, turn the main needle from the rich to the peaks
several times. When the peak become stable, open the throttle valve from low speed to high speed several times to check the
response. And gradually elongate the time of high-speed operation. Conduct this operation for one tank.
(5) When the revolution is stabilized at peak, the ground-level break-in is completed. After adjusting the tappet gap in the manner of
section "14", adjust the carburetor according to the following section. The running-in is completed by performing some 20 flights in
a little rich condition. Subsequently, the flight should be performed in such a rich condition as far as not to influence the flight.
12. Adjustment of carburetor
The principal method of adjustment is the same as that for our glow engine
* The slow needle is set so that idling rotation may be 1800rpm to 2100rpm at the factory default. However, since it may vary depending
on the condition at the time of operation, adjust it so as to meet the operating condition. (For the slow needle's reference value, refer to
the figure in the section "7").
In principle, a carburetor is adjusted by first achieving peak (the highest revolution) with the main needle and then performing idling (low
speed revolution) with the throttle valve and the slow needle. (Unless the peak is certainly achieved, idling adjustment will be difficult
and not stabilized.)
(1) After filling up the fuel tank, start the engine in the manner of Section "10" and then fully open the throttle valve with the throttle
(2) By turning the main needle depending on the rotating meter and the exhaust sound, achieve peak carefully.
* As for adjusting the main needle in the case of actual flight, setting the peak in the perpendicular attitude with a propeller in the
upward direction is recommended if it's possible. In that adjusting, it'll be rich enough in the horizontal attitude so it's more similar
to the condition during the actual flight.
Caution: Over closing the main needle is very dangerous because it may cause knocking and propeller nut loosening. Then, turn the main
needle CCW immediately to make it rich a little.
(3) Next, close the throttle valve until the engine operates stably with an idling rotation of around 1,800 - 2,000rpm, adjusting the slow
needle with the (-) screw driver and the throttle valve carefully.
*Since the richness level of the air-fuel mixture varies corresponding to the nature of the airframe, please adjust it depending on the
user's skill.
Generally, in a scale flight in which the stability of a low-speed zone is considered as important and the engine is operated slowly,
adjust the air-fuel mixture to be relatively lean. In an acrobatic flight in which the early stand-up from a low speed is considered as
important, adjust the air-fuel mixture to be slightly rich.
(4) After the idling is set, get the throttle valve slowly fully opened. If the revolution becomes slow or goes up suddenly, adjust carefully
until it changes linearly from idling to peak, by fine-tuning with the slow needle.
(5) After the above adjustment is completed, open the throttle valve from idling to peak quickly. If the revolution does not achieve peak
immediately but get delayed as the throttle valve is fully opened, fine-tune the main needle and perform the same process from
idling to peak quickly. Repeat this carefully until the response improves.
* The key to make the engine last for long life is operating with the slightly rich condition as far as it doesn't effect to the flight.
Adjustment is needed depending on the engine attachment direction, the propeller, the fuel, the plug, the climate condition, etc.


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