out 2 1/3 turns.
• Idle needle valve: With the throttle
barrel closed, turn the needle valve all
the way clockwise and then back out
4 turns.
• Set the throttle barrel at the fully
closed position before making any
adjustments.
General Operating
Procedures
(to ensure the long life of the engine)
• Do not operate the engine with a
“lean” mixture.
• Regularly check all screws and nuts
on both the engine and muffler.
• After 1 to 2 hours of operation,
valve adjustment may be necessary.
Adjust the valves as shown in the
Engine Maintenance and Valve/
Tappet Adjustment Sections.
• The Saito engines are
equipped with a “breather” nipple.
It is recommended that a length of
Tygon-type tubing be attached to this
crankcase breather nipple and routed
away from the engine compartment
so the excess oil can be expelled
outside of the aircraft.
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. If there is no
malfunction noted, it is normal.
• 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, in which 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.
• 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
T R O U B L E S H O O T I N G G U I D E
11
10
N O R M A L O P E R A T I O N A N D M A I N T E N A N C E
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, clean thoroughly and re-oil.
Then assemble them in the original
condition and place in a plastic or air-
tight container.
Troubleshooting
Guide
If the engine does not start:
• Check and use a new spark plug
if needed.
• Check fuel lines.
• Check for proper mechanical
function by turning the engine over.
• Check that the carburetor is
correctly installed.
Mechanical Faults
If the engine cannot be turned over
easily:
• It is likely that the piston in the
cylinder is seized.
• Visually examine the piston and
crankcase to find the likely cause of
the engine's mechanical problem.
Engine Maintenance
Do not needlessly disassemble your
Saito single-cylinder engine.
If you must disassemble your engine,
please refer to the following steps.
• Cylinder screws should be loosened
in a crisscross pattern.
• Assemble the cam gear lining up
the timing mark at the “6 o’clock”
position. The crankshaft must be
positioned at the “12 o’clock” or
“top dead center” (TDC) position.
Refer to figure below:
• Reassemble the piston, rod, rocker
arm, pins, pushrod, tappet, etc. in
their original positions. Engine
parts are mated after running
the engine and must be
reassembled as close as possible to
their original position.
• Assemble the engine, reversing
the crisscross pattern used in the
disassembly. Prior to tightening
each of the screws, apply a drop of
oil to prevent thread damage.
• Normal engine maintenance, such
as adjusting the valves or carburetor,
is permissible without voiding the
warranty. If you have any questions
concerning maintenance
procedures, please contact the Saito
Horizon Service Center at
877-504-0233. Our technicians will
be happy to advise you on
maintenance issues.
Cam (Intake or Exhaust)
Bench Mark
14387 SAI FG_20andFG_36 Manual.indd 10-11
12/16/08 2:09:13 PM
