
It is of vital importance, before attempting to
operate your engine, to read the general
'SAFETY INSTRUCTIONS AND WARNINGS'
section on pages 2-4 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
SAFETY INSTRUCTIONS AND
WARNINGS ABOUT YOUR O.S. ENGINE
NOTES WHEN APPLYING AN
ELECTRIC STARTER
ABOUT THE ENGINE
ENGINE PARTS NAME
RELOCATION OF CARBURETOR CONTROLS
FUEL TANK & LINES
INSTALLATION
EXHAUST HEADER PIPE & SILENCER
PROPELLER
FUEL
CONTENTS
MIXTURE CONTROLS
STARTING
RUNNING-IN ("Breaking-in")
MAINTENANCE
ENGINE EXPLODED VIEW
ENGINE PARTS LIST
CARBURETOR EXPLODED VIEW
& PARTS LIST
O.S. GENUINE PARTS & ACCESSORIES
ENGINE THREE VIEW DRAWINGS
2-4
5
6
7
8
9
10-11
12
13-14
15
16
17
18
19-21
22-23
24
25
26
27
28
GLOWPLUG

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 or
abused. 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.
WARNINGS
These cover events which might involve serious ( in
extreme circumstances, even fatal ) injury.
NOTES
These cover the many other possibilities, generally less
obvious sources of danger, but which, under certain
circumstances, may also cause damage or injury.
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
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 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 an 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.
Never operate your engine in an enclosed space. Model
engines, like automobile engines, exhaust deadly carbonmonoxide. Run your engine only in an open area.
Model engines generate considerable heat. Do
not touch any part of your engine until it has
coole d. Contact with the mu ffler(silencer),
cylinder head or exhaust header pipe, in
particular, may result in a serious burn.
3
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' recommendations, using appropriate
screws and locknuts.
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.
Always check the tightness of the propeller nut and retighten it, if necessary, before restarting the engine,
particularly in the case of four-stroke-cycle engines. If a safety locknut assembly is provided with your engine,
always use it. This will prevent the propeller from flying off in the event of a "backfire", even if it loosens. 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.
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.
Use an electric starter for this engine. The wearing of safety glasses is also strongly recommended.

4
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.
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!
NOTES
5
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.

6
ABOUT THE ENGINE
STANDARD ACCESSORIES
Needle Valve Extension Cable Set
This is an overhead valve four stroke cycle
engine for model aircraft use. This engine has
a largest displacement of 32.4cc in the FS
series and is suitable for scale and sport
models.
The engine is equipped with an easy to adjust
80N carburetor which can be reversed 180°
and supplied with a F-6010 silencer which
produces the milder four stroke sound.
F-6010 Silencer Assembly
Glowplug TypeF
7
ENGINE PARTS NAME
Rocker Cover
Glow Plug TYPE F
Lock Nut
Drive Hub
Crankcase
Beam Mount
Cover Plate
Exhaust Header Pipe
F-6010 Silencer Body
Cylinder Head
Carburetor Type 80N
Intake Manifold
Propeller Washer
Propeller Nut
Exhaust Header Pipe Nut M16

8
N.+M3x22
N.+M3x22
RELOCATION OF CARBURETOR CONTROLS
Carburetor Retaining Screw
Intake Manifold
Carburetor Retaining Screw
2.5x5xL85
Remove the carburetor retaining screws and remove the
silicone tube between the carburetor and cover plate.
Then, pull out the carburetor gently from the intake
manifold.
Rotate the carburetor 180°and insert on the intake
manifold straight and gently. Do not force at an angle or
the O ring inside the carburetor may be damaged.
Re-install the retaining screws. Then, connect the
carburetor and cover plate with a new silicone tube of
2.5mm inner dia and 5mm outer dia 85mm in length cut
from commercially available tubing.
Commercially available silicone tube
1.
2.
3.
Pull out the carburetor gently.
9
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.
For plumbing, use heavy duty silicone tube of 2.5mm inner
dia and 5mm outer dia.
The suggested fuel tank size is 500cc or 14 oz. This will
give approximately 10 minutes running time when some
part-throttle operation is included.
Locate the fuel tank so that the center line of the tank is 10
to 15mm below the center line of the needle-valve.
Approx. 15mm
Approx.
10-15mm
needle-valve Center Line
Fuel Tank Center Line
Locate the fuel tank as close to the engine as possible
to minimize fuel level variation.

10
INSTALLATION
It is suggested to use Lock Washers (available as an optional
extra) with engine installing screws or apply LOCTITE to the
screws to prevent them from loosening.
Because the FS-200S is a powerful, large-displacement,
single-cylinder four-stroke-cycle engines, it is essential to use
very substantial engine mounting. Conventional wooden
mounting beams should be of rigid hardwood and of at least
15mm or 5/8-in square section.
Make sure that these mounting beams are accurately aligned
and firmly integrated with the airframe, reinforcing the
adjacent structure to absorb vibration. Use 5mm or larger
steel screws, preferably Allen type hexagon socket head cap
screws, with washers and locknuts, for bolting the engine to
the bearers. As an alternative to wooden beam mounting, a
special O.S. cast aluminium radial motor mount, complete with
5mm mounting screws, is available as an optional extra part
(Code No.71904200) , when front bulkhead (firewall) type
mounting is called for. Engine installation should, be made in
such a way that basic maintenance can be conveniently
carried out.
How to fasten the mounting screws.
Hardwood mounting beams
O.S. radial motor mount
(cast aluminum)
Tighten second nut firmly
down onto first nut.
Tighten this nut first.
Steel washer
5mm steel nuts
5mm steel screw
Spring washer
or lock washer
15mm min.
15mm min.
Hardwood such as
cherry or maple.
Spring washer
5mm steel
Allen screw
CORRECT
Top surfaces are in the same plane.
INCORRECT
Front 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.
11
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. For this purpose, a Needle
Valve Extension Cable Set is supplied with the engine. If a
longer extension is reguired, 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
Set Screw
Knob
Cable

12
EXHAUST HEADER PIPE & SILENCER
IInstall these in the following sequence.
Screw the exhaust header pipe into the exhaust port until it
“bottoms”, then unscrew it approximately 90 degrees,and
secure with locknut.
Screw the silencer onto the header pipe more than 10mm and
maximum 30mm to achieve the desired exhaust angle and
tighten the other locknut.
The application of a heatproof silicone sealant to the threads of
the exhaust system is recommended to reduce the risk of joints
loosening and the leakage of exhaust gases and oil residue.
Also, make a habit to check the tightness periodically and
retighten if necessary.
The exhaust outlet can be rotated every 90 degrees by
removing the four assembly screws and rotate the rear part so
that the exhaust outlet can point required direction.
Be careful not to move the two gaskets and baffle plate at this
time.
Reminder:
Model engines generate considerable heat and contact
with the header pipe or silencer may result in a serious
burn. If you need to tighten the silencer joints, which may
loosen when they are hot, use a thick folded cloth for
protection.
M2.6x12
Gasket
Baffle plate
Can be rotated
by 90 degrees.
Exhaust outlet
Cap Screw
Silencer Assembly Screw
Apply silicone sealant.
Apply silicone sealant.
13
15x12-14, 16x12-14
17x10-13, 18x6-10
17x12-13, 18x8-12, 20x8
PROPELLER
The choice of propeller depends on the design and weight of
the aircraft and on 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, props than those shown in the table may be used, but
remember that propeller noise will increase if blade tip velocity
is raised, due to higher rpm or if a larger-diameter / lower-pitch
prop is used.
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-control system.
DO NOT forget the WARNINGS and NOTES on propeller
and spinner safety given on pages 2,3 and 4.
Warning:
Type
Size (DxP
)
/ Scale
Sport
1.
PROPELLER & SPINNER ATTACHMENT
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:
To be equal
To be equal
Ream to 8.1mm dia.
Ream the propeller shaft hole to 8.1mm bore with an
appropriate reamer, checking that the hole is exactly
centered.

14
Install the prop to the engine shaft, followed by the retaining
washer and prop nut and tighten firmly with a 14mm
wrench. (not supplied).
2.
3.
Add the special tapered and slotted locknut and secure
with a 12mm wrench while holding the prop nut with the
14mm wrench. (not supplied).
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:
Note:
Some spinners which are retained at the top of the cone
cannot be used with the prop locknut supplied with the
engine. In this case, optional locknut sets are available
from O.S. – Propeller Locknut Set for Spinner (Code
No.45910200 4mm) and (Code No.45910300 5mm).
Since the FS-200S is intended to be started with an electric
starter, the addition of a spinner assembly for centering the
starter sleeve is desirable. Special propeller locknut sets are
available for use with spinners.
Use a good quality well balanced spinner, enclosing the
propeller boss. Make sure that it is of precision-made and
sturdy construction so that the spinner shell cannot loosen
when the starter is used.
Make sure the spinner notches do not interfere the propeller.
If they do, cut the notches to clear.
15
The FS-200S should be operated on a methanol based fuel
containing not less than 18% castor-oil, or a top quality
synthetic lubricant (or a mixture of both), plus a small
percentage (5-30%) of nitromethane for improved flexibility
and power. The carburettor is adjusted at the factory for a fuel
containing 20% lubricant and 10% 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 performance. 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.
Reminders:
AII 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.
Though not as volatile as gasoline, model engine fuel is
also highly inflammable.
Keep it away from an open flame, excessive heat, sources
of sparks, or anything else that might ignite it. Smoking is
firmly discouraged.
FUEL

16
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.
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.
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.
17
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 idling 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 Screw only if necessary.
Two mixture controls are provided on this
Carburetor.
Needle Valve
Mixture Control Valve
Throttle Lever
Fuel Inlet
Rotor Guide Screw
MIXTURE CONTROLS
The sequence in which these controls are adjusted is
explained in the succeeding sections, under Starting,
Running-in and Idling Adjustment.
CARBURETOR CARE & MAINTENANCE
If you experience difficulty in achieving 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
Carburetor Parts Name
Breather
Inlet Nipple

18
The FS-200S 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 prime the
cylinder.
Starting procedure is as follows:
Check that the current to the glowplug is switched off.
Check that the polarity of the starter battery leads rotates the
engine counter-clockwise when viewed from the front.
Open the needle-valve 3-4 turns from the fully closed
position and set the throttle in the fully open position.
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.
1.
2.
3.
4.
5.
6.
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.
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.
7.
8.
Close the throttle-arm to within 15-20° of the fully closed
position and slowly turn the prop "backwards" (clockwise)
by hand approximately 1.5 turns until it is arrested by
compression.This is to enable the kinetic energy of the prop
to subsequently assist the starter through the compression
stroke to start the engine.
STARTING
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.
19
RUNNING-IN ("Breaking-in")
For long life and peak performance, every engine needs
special treatment when new, know as “running-in” or
“breaking-in”. This is a procedure during which the
engine is operated under strictly controlled conditions at
the beginning of its life, in order to avoid the risk of
immediate damage to certain components through
becoming overheated or stressed and to help working
surfaces to become smoothed and aligned for maximum
mechanical efficiency thereafter. With some engines, this
can require a tediously protracted period of bench
running, but, as O.S. engines are manufactured to fine
tolerances and from the finest quality materials, a
relatively brief running-in period is sufficient and can be
completed with the engine installed in the aircraft.
Prolonged running with too rich a mixture and/or low
speed will not complete the proper running-in. On the
other hand prolonged low speed running may cause the
oil in the fuel to congeal, which may result in seizure of
the piston and cylinder liner.
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 3-4 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.
5.
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.
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.

20
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.
8.
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.
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.
6.
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.
7.
Note:
Remember that, when the engine is not yet fully run-in,
the carburettor cannot be expected to give its best
response in flight. Abrupt operation of the throttle, for
example, may cause the engine to stall. Therefore, at this
time ,the aircraft should, as far as is possible, be flown at
an altitude sufficient to enable an emergency landing to
be safely made if the engine stops.
Once the engine has demonstrated that it can be safely
operated at full power, the carburettor can be adjusted for
optimum throttle response, following the instructions given
in the next section.
9.
21
In the course of making carburetor adjustments, it is just
possible that the Mixture Control Valve setting may be
upset.
Its basic setting can be re-established as follows:
First, set the throttle lever at fully closed position.
Turn the Mixture Control Valve counter-clockwise until it
stops, then screw it out 3 turns. This is the basic position.
REALIGNMENT OF MIXTURE CONTROL VALVE
Start the engine, open the throttle fully and set the needlevalve slightly rich (45-60°) 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 idling 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.
IDLE MIXTURE ADJUSTMENT
1.
2.
3.
4.
In paragraphs 3 and 4 above, the 45° total movements are,
of course, approximate. It will be necessary to fine-tune the
mixture control screw 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.
5.
6.
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. Also, a 5.5mm wrench (not supplied) is
required for this purpose.
• Wrench 5.5mm
• 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

22
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 dust in the fuel
container from entering the fuel tank. O.S. Super Filters (L)
is available as an optional extra.
Install an in-line fuel filter between the tank and carburetor
to prevent foreign matter 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 antidetonation combustion and increased power, have the
disadvantage of causing corrosion due to the acid byproducts 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 510 seconds with the electric starter.
Finally, inject some after-run oil through the glowplug hole
and turn the engine over several times by hand.
23
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.

24
Type of screw
C...Cap Screw M...Oval Fillister-Head Screw
F...Flat Head Screw N...Round Head Screw S...Set Screw
ENGINE EXPLODED VIEW
79871020
79871030
79871040
79871120
79871080
79871100
M2.6x7
M2.6x10
M2.6x12
M3x10
M3.5x12
M3.5x20
CAP SCREW SETS
(
10pcs./sets
)
Code No.
Size
Rocker Support Retaining Screw (1pc.)
Pcs. used in an engine
Cylinder Head Retaining Screw (6pcs.)
Cover Plate Retaining Screw (4pcs.)
Cam Cover Retaining Screw (3pcs.)
Silencer Assembly Screw (4pcs.)
Rocker Cover Retaining Screw (2pcs.)
C.M2.6x10
C.M3.5x20
C.M3.5x12
C.M2.6x7
C.M3x10
N.+M3x22
2
3
4
6
7
8
5
9
18
17
19
20
22
24
25
26
30
31
23
33
27
28
11
12
21
14
13
15
N.+M3x6
1
10
16
29
29
32
31-1
34
35
36
37
38
39-2
39-3
C.M2.6x12
39-1
39
39-4
39-5
25
The specifications are subject to alteration for improvement without notice.
123456789
101112131415161718192021222324252627282930
31
31-1
32333435363738
39
39-1
39-2
39-3
39-4
39-5
44504200
44514300
45761600
44561400
44561000
44561200
45560410
45560310
45560210
45560220
44550000
44551000
44504100
44514100
44514110
44569400
44581000
44503400
44503200
44506000
28117000
44505001
44503100
44507000
29061410
44502001
27930000
44501000
45231100
44562000
44501100
44501110
44566000
44566100
45566310
44564000
29431000
44508000
45910100
44525000
44525100
44525110
22681957
44525200
44525210
71615009
72200080
Description
Code No.No.
Rocker Cover
Rocker Cover Gasket
Rocker Arm Retainer (2pcs.)
Rocker Support
Rocker Arm (1pc.)
Tappet Adjusting Screw (1pair)
Split Cotter (2ps./1pair)
Valve Spring Retainer (1pc.)
Intake Valve Spring (1pc.)
Exhaust Valve Spring (1pc.)
Intake Valve (1pc.)
Exhaust Valve (1pc.)
Cylinder Head (W/Gasket)
Head Gasket (2pcs.)
Intake Manifold Gasket (2pcs.)
Intake Manifold
Carburetor Complete (Type 80N)
Piston Ring
Piston
Piston Pin
Piston Pin Retainer
Connecting Rod
Cylinder Liner
Cover Plate
Cover Gasket
Crankshaft
Crankshaft Ball Bearing (Rear)
Crankcase (W/Screw)
Camshaft Ball Bearing (1pc.)
Camshaft
Cam Cover (W/Gasket)
Cam Cover Gasket
Push Rod (2pcs.)
Push Rod Cover (1pc.)
Push Rod Cover "O" Ring (2pcs.)
Cam Follower (2pcs.)
Crankshaft Ball Bearing (Front)
Drive Hub (W/Collet)
Lock Nut Set
F-6010 Silencer Assembly
Silencer Body
Silencer Gasket (2pcs.)
Pressure Nipple (No.7)
Exhaust Header Pipe Assembly
Exhaust Header Pipe Nut m16 (1pc.)
Glow Plug Type F
Needle Valve Extension Cable Set
ENGINE PARTS LIST

26
1
1-1
1-2
1-3
1-4
1-5
2
3
4
5
6
6-1
6-2
7
8
8-1
9
10
23881900
22681980
24981837
26381501
27381940
26711305
22681953
44581100
45581820
45771000
44581600
46066319
24881824
44581200
27881400
22081313
44581500
45581700
Type of screw
C...Cap Screw M...Oval Fillister-Head Screw
F...Flat Head Screw N...Round Head Screw S...Set Screw
The specifications are subject to alteration for improvement without notice.
Description
Code No.
No.
EXPLODED VIEW & PARTS LIST
Needle-valve Assembly
Needle Assembly
"O" Ring (2pcs.)
Set Screw
Needle-valve Holder Assembly
Ratchet Spring
Fuel Inlet (Nipple No.1)
Carburetor Body
Roter Guide Screw
Breather Nipple (Nipple No.5)
Mixture Control Valve Assembly
"O" Ring (L) (2pcs.)
"O" Ring (S) (2pcs.)
Carburetor Rotor
Throttle Lever Assembly
Throttle Lever Retaining Screw
Carburetor Rubber Gasket (2pcs.)
Carburetor Retaining Screw
S.3x3
N.+M3x22
N.+M3x6
1-3
1-1
1-2
1-5
1-4
1
2
3
9
4
5
6-1
6-2
6
7
8
10
8-1
27
(72200130)
(71531000)
(72403050)
(71521000)
(71531010)
(71904200)
(72200110)
(72200060)
(79871020)
(79871030)
(79871040)
(79871120)
(79871080)
(79871100)
M2.6x7
M2.6x10
M2.6x12
M3x10
M3.5x12
M3.5x20
BOOSTER TERMINAL KIT
NON-BUBBLE WEIGHT
SUPER FILTER (L
)
LONG SOCKET WRENCH
WITH PLUG GRIP
O.S. GENUINE PARTS & ACCESSORIES
CAP SCREW SET (10pcs.)
The specifications are subject to alteration for improvement without notice.
BLIND NUT (10pcs.)
LOCK WASHER (10sets)
NON-BUBBLE WEIGHT
S
RADIAL MOTOR MOUNT
BOOSTER CABLE SET
VALVE ADJUSTING TOOL KIT
• Wrench 5.5mm
Also, a 5.5mm wrench (not supplied)
is required for this purpose.
(79870040)
(55500003)
M4
M4
(79870050)
M5
(55500004)
M5
(45910300)
(45910200)
PROPELLER
LOCKNUT SET FOR SPINNER
5/16"-M5
5/16"-M4

28
32.4 cc / 1.98 cu.in.
38.0 mm / 1.50 in.
28.6 mm / 1.13 in.
1,800 - 10,000 r.p.m.
2.9 ps / 9,000 r.p.m.
853 g / 30.09 oz.
116g (4.09 oz.)
58
64 25
50~70
37 77
58.5
97~117
82
67
48
30.5
25 119
144
UNF5/16-24
4- 5.1
Dimensions (mm)
THREE VIEW DRAWING
Specifications
Displacement
Bore
Stroke
PracticalR.P.M.
Output
Weight
(Silencer including
exhaust header pipe)
C
Copyright 2007 by O.S.Engines Mfg. Co., Ltd. All rights reserved. Printed in Japan.
60091910 031105
TEL. (06) 6702-0225
FAX. (06) 6704-2722
6-15 3-Chome Imagawa Higashisumiyoshi-ku
Osaka 546-0003, Japan
URL : http://www.os-engines.co.jp