Normal Operation, Maintenance And Additional Information; Setting The Needle Valves In The Gas 4-Stroke Engines - Saito FG-14C Owner's Operating Instruction Manual

Normal Operation, Maintenance and Additional Information

• Be sure to do a range check before flying your
model. It would be wise to do the range check with
the engine running and without it running. As a
simple noise check, after the engine is started, do
the normal range check your radio manufacturer
recommends.
• Be sure to charge the ignition battery and radio
system battery before the first flight of the day.
• To discharge the waste oil, connect a gasoline-proof
line from the breather nipple on the crankcase and
vent it outside of the aircraft.
• Lubrication of the piston, connecting rod, bearings
and cam gear is blow-by lubrication, where the oil in
the fuel goes into the crankcase from the clearance
between the cylinder and the piston. Engine life is
directly affected by the property of the fuel/oil mix.
Please use reliable oil.

Setting the Needle Valves in the Gas 4-Stroke Engines

Use a Tachometer
When setting any 4-stroke engine, it is critical that a
tachometer is used in setting the needle valves. It is
near impossible to set them properly by ear. A good
quality tachometer will go a long way towards improving
your usage of these engines and makes the experience
even more enjoyable. Make the investment.
Set the High-Speed Needle First
A general starting point for the high-speed needle on
the FG-14C carb is 1 turn 20 min. and the FG-17/FG-
21 carb is 1 turn 30 min.
1. Start the engine. Using your tachometer to gradually
lean the high-speed needle valve until the engine
reaches its peak rpm.
a. This will take some patience because it will take a
few seconds after making a 1 click needle change
to register an increase.
b. As you hit the perfect peak setting, you will notice
that there will be no rpm change.
c. Continue to lean the engine until you notice an rpm
decrease. It is only once you have experienced the
rpm decrease can you be sure you have actually
reached the peak setting.
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• Running the engine too lean causes heat; be sure
to run the engine slightly "rich" from peak. Running
too lean will cause "knocking" or engine failure and
has an adverse effect on the connecting rod and the
cam gear.
• Adjustment of the tappet is described in the "Valve/
Tappet Gap Adjustment" section.
• When attaching an exhaust pipe to the cylinder or
attaching a propeller nut, the use of threadlock is
recommended.
• Sometimes it is helpful to tighten an exhaust nut, etc.
when hot.
• When finished flying for the day, be sure to remove
fuel from the carburetor and the fuel tank.
• If the engine will not be operated for a long period
of time, remove the plug, rear cover, cylinder-
head cover, etc., then clean thoroughly and re-oil.
Assemble them in the original condition and place in
a plastic or air-tight container.
2. Once you are sure that you are on the lean side richen
(open) the high-speed needle back to the peak rpm.
3. Open the high-speed needle 2 clicks rich from your
confirmed peak and leave it there. You will likely
notice a small rpm difference on your tachometer, but
you will not likely be able to hear this drop in rpm.
Set the Low-Speed Needle
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 covers/
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.