O.S. engine FSA-72 Setup guide

It is of vital importance, before attempting to operate
your engine, to read the general 'SAFETY
INSTRUCTIONS AND WARNINGS' section on pages
2-6 of this booklet and to strictly adhere to the advice
contained therein.
● Also, please study the entire contents of this
instruction manual, so as to familiarize yourself
with the controls and other features of the engine.
Keep these instructions in a safe place so that you
may readily refer to them whenever necessary.
It is suggested that any instructions supplied with
the aircraft, radio control equipment, etc., are
accessible for checking at the same time.
●
●
1
2-6
7
8
9
10-13
20
21
27-28
34-35
36-37
38
17-18
SAFETY INSTRUCTIONS AND WARNINGS
ABOUT YOUR O.S. ENGINE
NOTES WHEN APPLYING AN ELECTTRIC STARTER
ABOUT THE ENGINE
ENGINE PARTS NAME
BEFORE STARTING
INSTALLATION
INSTALLING SILENCER
FUEL TANK & LINES
PROPELLER
GLOWPLUG
CONTENTS
MIXTURE CONTROLS
STARTING
RUNNING -IN ("Breaking-in")
IDLE MIXTURE ADJUSTMENT
CARE AND MAINTENANCE
ENGINE EXPLODED VIEW & PARTS LIST
CARBURETOR EXPLODED VIEWS
& PARTS LIST
GENUINE PARTS & ACCESSORIES
THREE VIEW DRAWING
MEMO
29-30
31-33
39
40
14-16
19
22-23
24-26

2
Remember that your engine is not a "toy", but a highly efficient internal-
combustion machine whose power is capable of harming you, or others, if it is
misused.
As owner, you, alone, are responsible for the safe operation of your engine, so act
with discretion and care at all times.
If at some future date, your O.S. engine is acquired by another person, we would
respectfully request that these instructions are also passed on to its new owner.
SAFETY INSTRUCTIONS AND WARNINGS ABOUT YOUR O.S. ENGINE
The advice which follows is grouped under two headings according to the
degree of damage or danger which might arise through misuse or neglect.
WARNINGS NOTES
These cover events which
might involve serious (in
extreme circumstances, even
fatal) injury.
These cover the many other
possibilities, generally less obvious
sources of danger, but which, under
certain circumstances, may also
cause damage or injury.
3
WARNINGS
Model engine fuel is poisonous. Do not
allow it to come into contact with the eyes
or mouth. Always store it in a
clearly marked container and
out of the reach of children.
Never operate your engine in an en-
closed space. Model engines, like auto-
mobile engines, exhaust deadly carbon-
monoxide. Run your engine only in an
open area.
Model engines generate considerable
heat. Do not touch any part of your
engine until it has cooled. Contact with
the muffler (silencer),
cylinder head or exhaust
header pipe, in particular,
may result in a serious burn.
Never touch, or allow any object to come
into contact with, the rotating
propeller and do not crouch
over the engine when it is
running.
A weakened or loose propeller may
disintegrate or be thrown off and, since
propeller tip speeds with powerful
engines may exceed 600 feet(180 metres)
per second, it will be understood that
such a failure could result in serious
injury, (see 'NOTES' section relating to
propeller safety).
Model engine fuel is also highly
flammable. Keep it away from open flame,
excessive heat, sources of sparks, or
anything else which might
ignite it. Do not smoke or allow
anyone else to smoke, near to it.

4
NOTES
This engine was designed for model
aircraft. Do not attempt to use it for any
other purpose.
Mount the engine in your model securely,
following the manufacturers' recommenda-
tions, using appropriate screws and lock-
nuts.
Be sure to use the silencer (muffler)
supplied with the engine. Frequent
exposure to an open exhaust may
eventually impair your hearing.
Such noise is also likely to cause
annoyance to others over a wide area.
Install a top-quality propeller of the
diameter and pitch specified for the engine
and aircraft. Locate the propeller on the
shaft so that the curved face of the blades
faces forward-i.e. in the direction of flight.
Firmly tighten the propeller nut, using the
correct size wrench.
If you remove the glowplug from the engine
and check its condition by connecting the
battery leads to it, do not hold the plug with
bare fingers.Use an appropriate tool or a
folded piece of cloth.
5
NOTES
Always check the tightness of the propeller
nut and retighten it, if necessary, before
restarting the engine. Also, check the
tightness of all the screws and nuts before
restarting the engine.
If you install a spinner, make sure that it is
a precision made product and that the
slots for the propeller blades do not cut into
the blade roots and weaken them.
Preferably, use an electric starter. The
wearing of safety glasses is also strongly
recommended.
Discard any propeller which has become
split, cracked, nicked or otherwise rendered
unsafe. Never attempt to repair such a
propeller: destroy it. Do not modify a propeller
in any way, unless you are highly experienced
in tuning propellers for specialized
competition work such as pylon-racing.
Take care that the glow plug clip or battery
leads do not come into contact with the
propeller. Also check the linkage to the
throttle arm. A disconnected linkage could
also foul the propeller.
After starting the engine, carry out any
needle-valve readjustments from a safe
position behind the rotating propeller. Stop
the engine before attempting to make other
adjustments to the carburetor.

6
NOTES
Adjust the throttle linkage so that the engine
stops when the throttle stick and trim lever
on the transmitter are fully retarded.
Alternatively, the engine may be stopped by
cutting off the fuel supply. Never try to stop
the engine physically.
Take care that loose clothing (ties, shirt
sleeves, scarves, etc.)do not come into
contact with the propeller.Do not carry loose
objects (such as pencils, screwdrivers, etc.)
in a shirt pocket from where they could fall
through the propeller arc.
Do not start your engine in an area
containing loose gravel or sand.
The propeller may throw such material in
your face and eyes and cause injury.
For their safety, keep all onlookers
(especially small children) well back (at
least 20 feet or 6 meters) when preparing
your model for flight. If you have to carry
the model to the take-off point with the
engine running, be especially cautious.
Keep the propeller pointed away from you
and walk well clear of spectators.
Warning! Immediately after a glowplug-
ignition engine has been run and is still
warm, conditions sometimes exist whereby
it is just possible for the engine to abruptly
restart if the propeller is casually flipped
over compression WITHOUT the glowplug
battery being reconnected. Remember this
if you wish to avoid the risk of a painfully
rapped knuckle!
7
NOTES WHEN APPLYING
AN ELECTRIC STARTER
Do not over-prime. This could
cause a hydraulic lock and damage
the engine on application of the
electric starter.
If over-primed, remove glowplug,
close needle-valve and apply
starter to pump out surplus fuel.
Cover the head with a rag to
prevent pumped out fuel from
getting into your eyes.

8
STANDARD ACCESSORIES
F-5030 Silencer Assembly
Silencer Body
ABOUT THE ENGINE
Exhaust Header Pipe
(W/M11 Lock Nuts)
Please note that this engine is not supplied
with any tools (e.g. Allen keys, wrenches, etc.)
This is the fourth model from the new FS
series of the single cylinder overhead valve
four cycle engines.
It features a sharp and modern look and
broad power band to suit a variety of model
types. Newly designed F-5030 silencer
minimizes noise with its soft, low-amplitude
sound. Threaded header pipe allows
adjustments in the distance between
silencer and exhaust and exhaust angle.
New lubricating system eliminates the need
for breather tubing from the crankcase. It
has the same mounting dimensions, drive
hub position and linkage position with the
FL-70.
Glowplug TypeF
9
ENGINE PARTS NAME
Rocker Cover
Drive Hub
Propeller Washer
Crankcase
Beam Mount
Cover Plate
Carburetor
Type 61N
Exhaust Header Pipe
Glow Plug TYPE F
Lock Nut
F-5030 Silencer Body
Cylinder Head
Intake Manifold Propeller Nut
Exhaust Header Pipe Nuts M11

10
Tools, accessories, etc. The following items
are necessary for operating the engine.
BEFORE STARTING
The choice of propeller depends on the design
and weight of the aircraft and the type of flying
in which you will be engaged.
Determine the best size and type after
practical experimentation. As a starting point,
refer to the props listed in the accompanying
table. Slightly larger, or even slightly smaller,
Propellers
Type
props than those shown in the table may be
used, but remember that the propeller noise
will increase, due to higher rpm or if a larger-
diameter/lower-pitched prop is used.
Never touch, or allow any object to come into
contact with, the rotating propeller and do not
crouch over the engine when it is running.
Reminder!
Warning:
Make sure that the propeller is well
balanced. An unbalanced propeller and/or
spinner can cause serious vibration which
may weaken parts of the airframe or affect
the safety of the radio-controlled system.
DO NOT forget the WARNINGS and NOTES
on propeller and spinner safety given on
front pages.
Scale
Sport & Aerobatic
Size(DxP)
12x7-8, 13x6-8
14x6-7
11
Since the FS -72 is intended to
be started with an electric starter,
the addition of a spinner
assembly for centering the starter sleeve is
desirable. Use a heavy-duty, well balanced
spinner either of metal or plastic.
Spinner
FUEL
The FS -72 should be operated on a methanol based
fuel containing not less than 18% (volumetric) castor oil,
or a top quality synthetic lubricant (or a mixture of both),
plus a small percentage (5-20%) of nitromethane for
improved flexibility and power. (The carburetor is
adjusted a little on the rich side at the factory for a fuel
containing 20% lubricant and 15% nitromethane.) Some
commercial fuels also contain coloring additives as an
aid to fuel level visibility. In some cases, these additives
have indicated slightly negative effects on the
performance.
Model engine fuel is poisonous. Do not
allow it to come into contact with the eyes or
mouth. Always store it in a clearly marked
container and out of the reach of children.
Model engine fuel is also highly flammable.
Keep it away from open flame, excessive
heat, sources of sparks, or anything else
which might ignite it. Do not smoke, or allow
anyone else to smoke, near to it.
Reminder!
We would suggest that you use such fuels only if you
are satisfied that they do not adversely affect running
qualities when compared with familiar standard fuels.
When changing to a fuel brand or formula that is
different from the one to which you are accustomed, it is
a wise precaution to temporarily revert to in-flight
running-in procedures, until you are sure that the
engine is running entirely satisfactorily.

12
A fuel tank of approximately
220cc capacity is suggested.
This allows around 12 minutes flying time,
dependent upon the type of fuel used, the size
of propeller and on the amount of full-throttle to
part-throttle operation throughout the flight.
Fuel Tank
GLOW PLUG
O.S. Type F glowplug is supplied with the engine.
GLOWPLUG IGNITER
Commercialy available handy
glowplug heater in which the
glowplug battery and battery leads are integrated.
Alternatively, one of the
purpose-made manual or
electric fuel pumps may be used to transfer fuel
directly from your fuel container to the fuel tank.
FUEL PUMP
Manual Electric
Electric Starter and
Starter Battery
Required when starting
the engine. 12-Volt lead-acid battery
Electric
Starter
Install a filter on the outlet tube of your
refueling container to prevent entry of
foreign matter into fuel tank. O.S. ‘Super Filters’
(large and small) are available as optional extras.
O.S. Super Filter (Fuel Can Filter)
S
To prevent the pickup from adhering to
the tank wall under suction and restricting
fuel flow, slots may be filed in the end of
the weight. Alternatively, an O.S. Non-
Bubble Weight is available as an optional
extra.
O.S. Non-Bubble Weight
13
It is recommended to install a good
in-line filter between the fuel tank and
carburetor to prevent entry of foreign matter
into the carburetor.
Fuel Filter
SILICONE FUEL LINE
Heatproof silicone tubing of approx.
5mm o.d. and 2.5mm i.d. is required for the
connection between the fuel tank and engine.
8mm
TOOLS
HEX Screwdriver
SCREWDRIVER
Necessary for engine installation.
1.5mm, 2.5mm
Necessary for carburetor adjustments.
Phillips Screwdriver
No.2, etc.
Socket Screwdriver
5mm, 5.5mm, 7mm
LONG SOCKET WRENCH WITH PLUG GRIP
Recommended for easy removal and
replacement of the angled and recessed
glowplug, the O.S.Long Socket Wrench
incorporates a special grip.
End Wrenches
10-12mm, etc.
Needle Nose Pliers

14
It is suggested to use as heavy and rigid as possible engine mounting for highest performance and
safe running. Conventional wooden mounting beams should be of rigid hardwood and of at least
15mm or 5/8-in square section. Use at least 3mm steel screws, such as Allen type, with locknuts, for
bolting the engine to the bearers..
INSTALLATION
CORRECT
Top surfaces are in the same plane.
INCORRECT
Rear view Side view
Re-align the surfaces
as necessary
Opposite beam
Top surfaces are not in the
same plane.
Engine does not rest firmly.
Top surfaces are not
in the same plane.
Make sure that the mounting beams are parallel and that their
top surfaces are in the same plane.
15
How to fasten the mounting screws.
Hardwood mounting beams
Radial motor mount (cast aluminum)
Tighten second nut
firmlydown onto first nut.
Tighten this nut first.
Steel washer
3mm steel nuts
3mm steel screw
Spring washer or
lock washer
15mm min.
15mm min. Hardwood such as
cherry or maple.
Spring washer
3.5mm
steel Allen screw
● Make sure that these mounting beams are
accurately aligned and firmly integrated with
the airframe, reinforcing the adjacent
structure to absorb vibration. Use 4mm or
larger steel screws, preferably Allen type
hexagon socket head cap screws, with
washers and locknuts, for bolting the engine
to the bearers.
O.S. Radial Motor Mount
A special O.S. radial motor mount (Code
No.71905010) is available, as an optional
extra, for use where firewall type mounting is
required.

16
THROTTLE LINKAGE
Before connecting the throttle to its servo,
make sure that the throttle arm and linkage
safely clear any adjacent part of the airframe
structure, etc., as the throttle is opened and
closed. Connect the linkage so that the throttle
is fully closed when the transmitter throttle
stick and its trim lever are at their lowest
settings and fully open when the throttle stick
is in its fully-open position. Carefully align the
appropriate holes in the throttle arm and servo
horn so that they move symmetrically and
smoothly through their full travel.
NEEDLE-VALVE EXTENSION
The needle-valve supplied with this engine is
designed to incorporate an extension so that,
when the engine is enclosed within the
fuselage, the needle-valve may be adjusted
from the outside. Cut a commercially available
rod to the required length, bend one end to an
L shape, insert it into needle's center hole and
secure it by tightening the set-screw in the
needle-valve knob with 1.5mm Allen key.
Needle Valve Extension Cable Set (Code No.
72200080) is available from O.S. as an
optional part.
Needle Valve Extension
Cable Set
1.5mm Allen key. Set Screw
17
INSTALLING SILENCER
Apply silicone
sealant.
Exhaust
Header Pipe
Exhaust Header
Pipe Nuts
Screw the exhaust header pipe in the
cylinder head to the bottom and secure it
with the nut. (A short screw in depth may
damage the threads of the cylinder head
due to vibration.)
1.
Screw the silencer on the exhaust header
pipe more than 8mm (10 turns) and secure
it with the nut. (A short screw in depth may
break the silencer or header pipe due to
vibration.) The distance between silencer
and cylinder head can be adjusted by
approximately 7mm by screwing the silencer
on or out the header pipe. Adjust the
silencer position by rotating the silencer.
2.
3. Apply silicone sealant to the threads to
prevent the silencer and header pipe from
loosening and leaking oil.

18
The exhaust outlet of the silencer can be rotated
to any desired position in the following manner:
Loosen the locknut and assembly screw.
Set the exhaust outlet at the required posi-
tion by rotating the rear part of the silencer.
Re-tighten the assembly screw, followed by
the locknut.
Assembly screw
Baffle
Turn to reguired
position
Exhaust outlet
Locknut
Exhaust pressure nipple
Model engines generate considerable heat.
Do not touch any part of your engine until
it has cooled. Contact with the muffler
(silencer), cylinder head or exhaust header
pipe, in particular, may result in a serious
burn. Keep your hands and face away from
exhaust gas or you will suffer a burn.
Reminder!
1)
2)
3)
"O" Ring
"O" Ring
19
FUEL TANK & LINES
Make sure that the tank is well rinsed out
with methanol or glow fuel before installation
and that the pickup weight is well clear of
the bottom of the tank when held vertically.
Plug (commercially available)
For carburetor
Approx. 10mm
Approx.
1/3
Carburetor Center Line
Locate the fuel tank as close to the
engine as possible to minimize fuel
level pressure variation.
For Silencer
Approx.
2/3
Be sure to use a pressurized fuel system by
connecting the muffler pressure nipple to the
vent-pipe of the fuel tank.
Use a suitable length of best quality 5mm
OD x 2.5mm ID silicone tubing for fuel
tubing.
The Fuel line pickup weight should be 10mm
away from the back of the tank.
Position the fuel tank so that approximately
1/3 of the tank height is above the center line
of the needlevalve.
Suggested fuel tank capacity is approx
220cc. This will allow 12minute flights.

20
PROPELLER
There is a risk, particularly with powerful four-
stroke engines, of the propeller flying off if the
prop nut loosens due to detonation
("knocking") in the combustion chamber when
the engine is operated too lean, or under an
excessively heavy load.
Obviously, this can be very hazardous. To
eliminate such dangers, the O.S. Safety
Locknut Assembly was devised.
Install this as follows:
Install the prop to the engine shaft, followed
by the retaining washer and prop nut and
tighten firmly with a 12mm wrench. (not
supplied).
2.
1.
Add the special tapered and slotted locknut
and secure with a 10mm wrench (not
supplied) while holding the prop nut with the
12mm wrench.
Propeller washer
Propeller nut
Locknut
Make a habit of always checking the
tightness of the propeller before starting
the engine. Remember that, especially with
wooden propellers, there is a tendency for
the material to shrink, or for it to be
reduced by the serrated face of the drive
hub. Retighten the propeller nut if
necessary after loosening the Safety
Propeller Locknut. The locknut should be
tightened firmly after retightening the
propeller nut.
NOTE:
21
Since the compatibility of the
glowplug and fuel may have a
marked effect on performance and
reliability, it is suggested to use the
O.S. Type F plug when it is
necessary to replace.
Carefully install plug finger-tight,
before final tightening with the
correct size plug wrench.
GLOWPLUG
The role of the glowplug
Glowplug life
Particularly in the case of very high performance
engines,
glowplugs must be regarded as expendable
items. However, plug life can be extended and engine
performance maintained by careful use, i.e.:
Install a plug suitable for the engine.
Use fuel containing a moderate percentage of
nitromethane unless more is essential for racing events.
Do not run the engine too lean and do not leave the
battery connected while adjusting the needle.
With a glowplug engine, ignition is initiated by the
application of a 1.5-volt power source. When the
battery is disconnected, the heat retained within the
combustion chamber remains sufficient to keep the
plug filament glowing, thereby continuing to keep the
engine running. Ignition timing is 'automatic' : under
reduced load, allowing higher rpm, the plug becomes
hotter and, appropriately, fires the fuel/air charge
earlier; conversely, at reduced rpm, the plug become
cooler and ignition is retarded.
Apart from when actually burned out, a plug may
need to be replaced because it no longer delivers its
best performance, such as when:
When to replace the glowplug
Filament surface has roughened and turned white.
Filament coil has become distorted.
Foreign matter has adhered to filament or plug
body has corroded.
Engine tends to cut out when idling.
Starting qualities deteriorate.

22
MIXTURE CONTROLS
RELOCATION OF CARBURETOR CONTROLS
Carburetor Retaining Screw
Intake Manifold
Retaining Screw
Remove the intake manifold retaining
screws and carburetor retaining screws.
1.
The carburetor can be turned 180 to
reverse the needle-valve and throttle lever
position.
2.Rotate the intake manifold 180 gently
without removing the carburetor from the
intake manifold.
Re-install the intake manifold and carburetor
retaining screws. Make sure the fitting faces
are clean. Do not over-tighten the screws.
3.
23

TYPE 61N CARBURETTOR
The sequence in which these controls are
adjusted is explained in the succeeding
sections, under Starting, Running-in and Idle
Adjustment.
The Needle Valve
When set to produce maximum power at full
throttle, this establishes the basic fuel/air
mixture strength. The correct mixture is then
maintained by the carburetor's built-in
automatic mixture control system to cover
the engine's requirements at reduced throttle
settings.
The Mixture Control Valve
This meters fuel flow at part-throttle and idle
speeds to ensure reliable operation as the
throttle is opened and closed. The Mixture
Control Valve is factory set for the
approximate best result. First run the engine as
received and readjust the Mixture Control Valve
only if necessary.
Two mixture controls are provided on this
Carburetor.
Needle Valve
Mixture Control
Valve
Air Funnel
Throttle Lever
Fuel Inlet
Rotor Guide Screw

24
STARTING
The FS -72 is not equipped with manual
choke controls, as it is intended for use
with an electric starter only.
A high-torque electric starter not only
makes starting the engine easier, it
dispenses with the need for a choke valve
by turning the engine over fast enough to
the cylinder automatically.
Starting procedure is as follows:
Fill the fuel tank with fuel. When filled,
prevent fuel flowing into the carburetor with
a commercially available fuel stopper, etc.
Release the stopper before starting the
engine.
Make sure that the plug element glows red,
and install the plug in the cylinder head.
1.
2.
Glow Plug Igniter
Pliers
Element glows when energized.
Replace the plug when the
element does not glow or is
burnt out.
WARNING
When checking the plug element hold the
plug with tools, such as pliers, etc.
Do not hold near your face or the fuel
remaining in the filament may burn you.
25
Check that the current to the glowplug is
switched off.
3.
To close the needle-valve, turn it clockwise,
while to open the needle-valve, turn it
counter-clockwise. Turn the needle-valve
clockwise slowly until it stops. This is the
fully closed position.
4.
Open the needle-valve 2.5-3 turns from the
fully closed position and set the throttle in the
fully open position.
5.
Apply the starter and press the starter switch
for 5-6 seconds, or until fuel is seen to
emerge from the exhaust outlet, indicating
that the cylinder is now primed.
Energize the glowplug and apply the starter.
If the starter fails to rotate the engine
completely, this may be due to the cylinder
being over-primed, or to the starter battery
being insufficiently charged.
Turn the prop “backwards” (clockwise) by
hand until it is against compression. This is
to enable the kinetic energy of the prop to
subsequently assist the starter through the
compression stroke to start the engine.
6.
7.
8.
Mark
Close
Open
Fully closed
position
Fully opened
position
1
4

26
Check these conditions and, instead of
pressing the starter button after applying
the starter, have the starter spinning before
applying it to the engine, to give it a
"running start".
When the engine starts, slowly open the
throttle, leaving the needle-valve at its rich
starting setting to promote cool running
conditions. However, if the engine slows
down because the mixture is excessively
rich, the needle-valve may be closed a little
to speed it up until it runs evenly.
7.
8.
Note:
Make sure that the throttle linkage is made
so that the throttle is fully closed when the
throttle lever as well as trim lever on the
transmitter are fully pulled down.
How to stop the engine
Pull down the throttle lever and trim lever on
the transmitter fully.
Electric starter
Make sure that the
direction or rotation
is correct.
Now disconnect current to the glowplug and
gradually close the needle-valve so that the
rpm increases.
Make adjustments to the needle in small
steps.
Abrupt changes at this stage are likely to
cause the engine to stall. Restart the engine
by simply applying the starter with the
glowplug re-energized and the throttle at its
starting setting.
27
RUNNING-IN ("Breaking-in")
The recommended procedure is as follows:
Use the same fuel and prop as you intend
for flying your model.
1.
2. Open the needle-valve 2.5-3 turns from the
fully closed position and start the engine.
3. Open the throttle slowly to the mid speed
position, and disconnect the current to the
glowplug.
4. Now open the throttle slowly to the fully
opened position and run the engine for no
more than 5 seconds with the needle-valve
tuned to produced near maximum r.p.m.,
then, immediately, slow the engine down
again by opening the needle-valve
approximately one turn. The rich mixture, so
induced, will cool the engine, at the same
time providing increased lubrication.
All internal-combustion engines benefit from
extra care when they are run for the first few
timesknown as running-in or breaking-in. This
allows the working parts to mate together
under load at operating temperature.
Therefore, it is vitally important to complete the
break-in before allowing the engine to run
continuously at high speed and before
finalizing carburetor adjustments. However,
because O.S. engines are produced with the
aid of the finest modern precision machinery
and from the best and most suitable materials,
only a short and simple running-in procedure is
called for and can be carried out with the
engine installed in the model.
5. Repeat this process, alternately running the
engine fast and slow by means of the
needle-valve, while keeping the throttle fully
open, then begin to extend the short periods
of high-speed operation until two tanks of
fuel have been consumed.

28
WARNING:
When ground running the engine, avoid
dusty or sandy locations. If dust or grit is
drawn into the engine, this can have a
ruinous effect, drastically shortening
engine life in a matter of minutes.
Following the initial running-in session, check
for any looseness in the installation due to
vibration, then allow the engine a period of
moderately rich operation in flight.
For the first flight, have the needle-valve set
on the rich side and adjust the throttle trim on
the transmitter so that the engine does not
stop when the throttle is closed to the idle
setting.
8.
6.
With each successive flight, close the
needle-valve very slightly until, at the end of
about 10 flights, the needle is set for full
power. Do not "over-lean" the mixture in an
attempt to extract more power.
If overheating should be suspected at any
time during flight (i.e.if the engine begins
to "labor") reduce power by partially
closing the throttle and land the aircraft to
enable the needle-valve to be readjusted to
a richer setting.
7.
29
IDLE MIXTURE ADJUSTMENT
Start the engine, open the throttle fully and
set the needle-valve slightly rich (30-45°)
from the highest r.p.m. setting.
Close the throttle to the idle position. Allow
the engine to idle for about 5 seconds, then
reopen the throttle. The engine should
accelerate smoothly back to full speed.
If, instead, the engine responds sluggishly
and emits an excess of white smoke from
the exhaust, the idle mixture is too rich. Turn
the mixture control valve approx. 45°
clockwise to lean the idle mixture.
On the other hand, if the engine hesitates
before picking up speed or even ceases
firing completely, the idle mixture is likely to
be too lean. Turn the mixture control valve
90°counter-clockwise to substantially enrich
the mixture, then back again 45°clockwise.
In paragraphs 3 and 4 above, the 45°total
movements are, of course, approximate. It
will be necessary to fine-tune the mixture
control valve 10-15°at a time to reach the
best setting for optimum throttle response.
Continue re-checking the idle mixture
setting until the engine responds smoothly
and positively to operation of the throttle at
all times.
1.
2.
3.
4.
5.
6.

30
CARBURETOR CARE & MAINTENANCE
If you experience difficulty in obtaining a
consistent mixture setting it could be due to
foreign debris in the carburetor. Carefully
disassemble the carburetor and wash in
methanol. Do not use gasoline or kerosene
that can effect the silicone rubber "O" rings.
Debris tends to accumulate in
this area
Mixture Control Valve
Carburetor Body
REALIGNMENT OF MIXTURE CONTROL VALVE
In the course of making carburetor
adjustments, it is just possible that the
Mixture Control Valve may be inadvertently
screwed in or out too far and thereby moved
beyond its effective adjustment range.
Rotate the Mixture
Control Valve until its
slotted head is flush with
the carburetor body.
Then, screw it in by
1mm (two turns). This is
the basic position.
31
VALVE ADJUSTING
Valve clearances are correctly set before
any O.S. engine leaves the factory and, in
normal use, will seldom require adjustment.
However, if, after a considerable amount of
running time, a loss of power is detected, or
if he engine has been disassembled for
repair, these clearances should be checked
and reset as necessary.
For checking and adjusting the valve
clearances, a VALVE ADJUSTING TOOL
KIT is available as an optional accessory.
• Feeler gauge 0.04mm
The kit comes in a plastic case and includes:
(Code No.72200060)
• Feeler gauge 0.1mm
• Hex. key 1.5mm
• Wrench 5mm
CARE AND MAINTENANCE
Please pay attention to the matters
described below to ensure that your engine
serves you well in regard to performance,
reliability and long life.
As previously mentioned, it is vitally important
to avoid operating the engine in conditions
where dust, disturbed by the propeller, may
be deposited on the engine and enter its
working parts.
Remember to keep your fuel container
closed to prevent foreign matter from
contaminating the fuel.
Install a fuel filter to prevent dirt and foreign
matter in the fuel container from entering the
fuel tank. O.S. Super Filters (L) and (S) are
available as optional extras.

32
Install an in-line fuel filter between the tank
and carburetor to prevent dirt and foreign in
the tank from entering the carburetor.
If these precautions are neglected, restriction
of fuel flow may cause the engine to cut out,
or the fuel/air mixture to become too lean
causing the engine to overheat.
Clean these filters periodically.
The use of modern high-performance alcohol
based model engine fuels, while promoting
cooler running, improved anti-detonation
combustion and increased power, have the
disadvantage of causing corrosion due to the
acid by-products of combustion.
The use of nitromethane in the fuel can also
contribute to the problem.
Do not close the needle-valve and mixture
control valve too far as this will cause a lean
setting and over heating of the engine. This
can, in turn, create nitromethane oxide
leading to internal rusting of the engine.
Always adjust the needlevalve slightly on the
rich side of peak rpm.
Do not leave unused fuel in the engine at the
conclusion of a day’s flying. Accepted
practice is to cut off the fuel supply while the
engine is still running at full throttle, then
expel as much fuel residue as possible by
turning the engine over 5-10 seconds with
the electric starter.
Finally, inject some after-run oil through the
glowplug hole and turn the engine over
several times by hand.
33
When the engine is not to be used for some
months (for example, as between flying
seasons), a worthwhile precaution is to
remove it from the airframe and, after
washing off the exterior with alcohol (not
gasoline nor kerosene), remove carefully the
carburetor with intake pipe, glow plug and all
silicone tubing and put them safely aside.
Then, immerse the engine in a container of
alcohol. Rotate the crankshaft while the
engine is immersed. If foreign matter is
visible in the alcohol, rinse the engine again
in clean alcohol. Finally, shake off and dry
the alcohol ,and inject some after-run oil in
the glowplug hole and rotate the crankshaft
several times by hand. Reinstall the
carburetor with intake pipe and glowplug on
the engine and keep it in a dry place after
putting in a vinyl bag.

34
ENGINE EXPLODED VIEW & PARTS LIST
Type of screw
C...Cap Screw N...Round Head Screw
CAP SCREW SETS (10pcs./sets)
Code No. Size
Rocker Support Retaining Screw (1pc.)
Pcs. used in an engine
Cylinder Head Retaining Screw (5pcs.)
Cover Plate Retaining Screw (4pcs.)
Cam Cover Retaining Screw (2pcs.) Intake Manifold Retaining Screw (2pcs.)
Rocker Cover Retaining Screw (2pcs.)
79871020 79871030 79871110 79871150 79871200
M2.6x7 M2.6x10 M3x8 M3x15 M3x20
C.M3x15
C.M3x20
C.M2.6x10
2
35
4
6
1
7 8
C.M2.6x7
N.+M3x22
C.M3x8 C.M2.6x7
910 11
12
13 14
15
16 17
18
19
20
21
22
23
24
27
28
29
25
26
31
30
31-1
32
11-1
23
33-3
33-4
33-2
33-1
33-6
33-5
33
33-3
35
The specifications are subject to alteration for improvement without notice.
Rocker Cover Rocker Arm Retainer (2pcs.) Rocker Support (1pc.) Rocker Arm (1pc.) Tappet Adjusting Screw (1pair) Split Cotter (2pcs.) Valve Spring Retainer (1pc.) Valve Spring (1pc.) Intake Valve (1pc.) Exhaust Valve (1pc.) Cylinder Head (W/Gasket) Cylinder Head Gasket (1pc.) Intake Manifold (1pc.) Carburetor Complete (Type 61N) Piston Ring Piston Piston Pin Connecting Rod Cylinder Liner Cover Plate Crankshaft Crankshaft Ball Bearing (Rear) Crankcase Camshaft Ball Bearing (1pc.) Camshaft Cam Cover Push Rod (2pcs.) Push Rod Cover (1pc.) Push Rod Cover "O" Ring (2pcs.) Cam Follower (2pcs.) Crankshaft Ball Bearing (Front) Drive Hub (W/woodruff key) Woodruff Key Lock Nut Set F-5030 Silencer Assembly Silencer Body Assembly Screw Silencer Gasket (1pc.) Pressure Nipple (No.7) Exhaust Header Pipe Assembly Exhaust Header Pipe Nut M11 (1pc.) Glow Plug Type F
No. Code No. Description
1 2 3 4 5 6 7 8 9
10 11
11-1
12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
31-1
32 33
33-1 33-2 33-3 33-4 33-5 33-6
44304200 45761600 45961410 44861000 45061202 45960400 45960310 45960210 44750100 44751100 44304100 44714100 44369400 44381000 44303400 44303200 44306000 44305000 44303100 44307000 44302000 44230000 44301000 45231100 44362000 44301100 44366000 44366100 27881840 45664000 26531005 44308000 27708200 45810100 44825000 44825100 44825400 44625410 22681957 44825200 45626030 71615009

36
CARBURETOR EXPLODED VIEW
Type of screw
C...Cap Screw M...Oval Fillister-Head Screw
F...Flat Head Screw N...Round Head Screw S...Set Screw N.+M3x6
S.M3x3
1
1-1
2
3
4
5
6
7
8
9
10
9-1
S.M3X3
N.+M3x22
2-1
1-2
7-1
7-2
10-1
11
37
CARBURETOR PARTS LIST
Needle Assembly
"O" Ring (2pcs.)
Set Screw
Needle Valve Holder Assembly
Ratchet Spring
Carburetor Body
Fuel Inlet (No.1)
Carburetor Rubber Gasket (1pc.)
Rotor Guide Screw
Mixture Control Valve Assembly
"O" Ring (L) (2pcs.)
"O" Ring (S) (2pcs.)
Carburetor Rotor
Throttle Lever Assembly
Throttle Lever Retaining Screw
Air Funnel
Set Screw
Carburetor Retaining Screw (2pcs.)
Description
Code No.
No.
Specifications are subject to alteration for improvement without notice.
1
1-1
1-2
2
2-1
3
4
5
6
7
7-1
7-2
8
9
9-1
10
10-1
11
44881970
24981837
26381501
27381940
26711305
44381100
22681953
46115000
45581820
45582300
46066319
24881824
44381200
22081408
22081313
44381300
26381501
45581700

38
The specifications are subject to alteration for improvement without notice.
O.S. GENUINE PARTS & ACCESSORIES
RADIAL MOTOR MOUNT
1/4"-M5
(71905010)
(45810200)
(45810300)
(72200130)
BOOSTER
TERMINAL KIT
PROPELLER LOCKNUT
SET FOR SPINNER
1/4"-M4
(71531000)
(71531010)
(72403050)
(71521000)
SUPER FILTER
LONG SOCKET WRENCH
WITH PLUG GRIP
(L)
VALVE ADJUSTING
TOOL KIT
NON-BUBBLE
WEIGHT
NON-BUBBLE
WEIGHT
(S)
(72200060)
(72109680)
M11 IN-COWL HEADER PIPE
INVERTED 80D
IN-COWL EXHAUST
HEADER PIPE
M11 IN-COWL HEADER PIPE
SIDE 60D
(72109690)
(72200080)
Needle Valve
Extension Cable Set
39
Displacement
Bore
Stroke
Practical R.P.M.
Power output
Weight
SPECIFICATIONS
Dimensions(mm)
THREE VIEW DRAWING
F-5030 Silencer Assembly
54 g / 1.9 oz.
11.79 cc / 0.720 cu.in.
27.0 mm / 1.063 in.
20.6 mm / 0.811 in.
2.400-12.500 r.p.m.
1.2 ps / 11.000r.p.m.
476 g / 16.79 oz.
45
21.3
49.5
59.5
44.1
91
103.6
36
90
108
33.7
UNF1/4-28
4- 3.7
20
11