O.S. Engines 50SX User Manual

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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.

CONTENTS

SAFETY INSTRUCTIONS AND WARNINGS ABOUT YOUR O.S. ENGINE

FEATURES OF FX SERIES ENGINES, BEFORE INSTALLING THE ENGINE

BASIC ENGINE PARTS NEEDLE-VALVE LOCATION INSTALLATION OF THE ENGINE THROTTLE LINKAGE, SILENCER FUEL T ANK LOCATION GLOWPLUG FUEL, PROPELLERS MIXTURE CONTROLS BEFORE STARTING

10 12 12 13 15 15 17

STARTING

RUNNING-IN (Breaking-in) IDLING ADJUSTMENT CHART

MIXTURE CONTROL VALVE ADJUSTMENT,

REALIGNMENT OF MIXTURE CONTROL VALVE

SUBSEQUENT STARTING PROCEDURE SUBSEQUENT READJUSTMENT

CARBURETOR CLEANLINESS, ENGINE CARE AND MAINTENANCE

ENGINE EXPLODED VIEWS & ENGINE PARTS LISTS

CARBURETOR EXPLODED VIEWS & PARTS LISTS

GENUINE O.S. PARTS & ACCESSORIES ENGINE THREE VIEW DRAWINGS MEMO

17~18

36 38

41 42

SAFETY INSTRUCTIONS AND WARNINGS ABOUT YOUR O.S. ENGINE

Remember that your engine is not a "toy", but a highly efficient internalcombustion 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.

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

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.

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 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 cooled. Contact with the muffler (silencer), cylinder head or exhaust header pipe, in particular, may result in a serious burn.

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.

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.

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.

NOTES

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.

If you fit 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.

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!

FEATURES OF FX SERIES ENGINES

This range of engines is ideally suited to a variety

• of R/C aircraft, including trainer, sports, aerobatic and scale types.

A separate precision-made needle-valve unit is

• installed at the rear, where manual adjustment is safely remote from the rotating propeller.

With the 50SX, 61FX and 91FX, the needle-valve

• assembly can be installed either horizontally or vertically.

Common to accessories

Glow Plug No.8, Silicone Tube, Instruction Manual

50SX, 40/46FX 61FX 91FX

Note : With these engines, the piston will feel tight at the top of its stroke when the engine is cold. This is normal. The piston and cylinder are designed to achieve a perfect running clearance when they reach their intended running temperature.

873 Silencer Assembly E-4010 Silencer Assembly

E-4020 Silencer Assembly Needle Valve Extension Cable

BEFORE INSTALLING THE ENGINE

Installing the glowplug

Carefully insert plug, with washer, fingertight only, before final tightening with the correct size plug wrench.

Connecting fuel tubing

Connect the short length of fuel tubing (supplied) securely between the needle-valve outlet and carburetor inlet as shown in the illustration on the next page. In the event of the tubing becoming damaged, it should be replaced with a suitable length (as indicated below) of best quality 5mm ODx2mm ID silicone tubing. Use similar material to connect the fuel inlet nipple to the fuel tank.

Type of engines

50SX

46FX

Length

56mm 61FX

46mm

Glow plug

Washer

Type of engines

91FX

Length 54~56mm 62mm

BASIC ENGINE PARTS

Cylinder head

Throttle Stop Screw

Carburetor

Throttle Lever

Crankcase

Fuel inlet

Drive Hub

Crankshaft

Propeller washer

Propeller nut

Glowplug

Beam Mount

Fuel inlet

Needle valve

Fuel outlet

Cover Plate

Silicone Tube

MAX-61FX

NEEDLE-VALVE LOCATION

As delivered from the factory, the MAX-61FX and MAX-91FX installed horizontally. However, if more convenient for a particular installation, the needle-valve may be reinstated vertically behind the cylinder. (See sketch opposite.) Please note that the needle-valve knob has a center hole and set-screw for the fitting of a piano-wire extension (supplied with the 91FX) so that, when relocated vertically, the extension enables adjustments to be made without risk of burning one's fingers on the cylinder head.

The proce is as follows:

RING have their needle-valve assembly

dure for relocating the needle-valve vertically

Using 8mm wrench, remove complete needle-valve holder assembly including needle, from side of cover plate.

Remove fuel inlet assembly from upper boss of cover plate.

Transfer banjo type fuel inlet including washers, to needle-valve holder and carefully screw complete assembly into upper boss vacated by fuel inlet assembly. Tighten very carefully.

Use hexagon-head brass inlet holder (61FX) or plug screw (50SX/91FX) to blank off side boss vacated by needle- valve assembly.

61FX

Needle Extension

Inlet Holder

Fuel Inlet

Needle-Valve Assembly

Fuel Inlet

45mm

50SX/91FX

Plug Screw (50SX/91FX)

Fuel Inlet

Needle-Valve Assembly

Needle Extension

Needle-Valve Assembly

Fuel Inlet

Plug Screw (50SX/91FX)

45mm

Needle-Valve Assembly

Inlet Holder

INSTALLATION OF THE ENGINE

Installation in the model

A typical method of beam mounting is shown below, left.

Rigid hardwood (e.g. maple)

At least 15mm(5/8")

50SX

46FX

91FX

At least 15mm(5/8")

For 50SX, 40/46FX(Code No. 71913100) For 60FP, 61

Mounting Screw Size

50SX, 40¡46FX

91FX

O.S. radial motor mount (Available as an optional extra part. See parts list)

91FX(Code No. 71905200)

3mm 4mm

Make sure that the mounting beams are parallel and that their top surfaces are in the same plane.

CORRECT INCORRECT

Front view Side view

Top surfaces are in the same plane.

Top surfaces are not in the same plane.

Re-align the surfaces as necessary

Opposite beam

Engine does not rest firmly.

Top surfaces are not in the same plane.

How to fasten the mounting screws.

3-4mm steel nuts

Spring washer or lock washer

3-4mm steel screw

Hardwood mounting beams

Use mounting screws of a diameter (between 3mm and 4mm) appropriate to engine size (see table left).

Tighten second nut firmly down onto first nut.

Tighten this nut first.

Hardwood such as cherry or maple.

Steel washer

O.S. radial motor mount (cast aluminum)

3.5mm steel Allen screw

Spring washer

THROTTLE LINKAGE

Before connecting the throttle-lever/servo linkage,

•

make sure that no part of the linkage interferes with the internal structure of the aircraft or wiring, etc., when the throttle is fully open or fully closed.

Set the throttle lever linkage so that the throttle ro-

•

tor is (a) fully open when the transmitter throttle stick is fully advanced and (b) fully closed when the throttle stick is fully retarded. Adjustment of the throttle rotor opening at the idling position can then be made with the throttle trim lever on the transmitter. (Select throttle-lever and servo-horn hole positions that will avoid excessive pushrod travel causing the throttle to bind at either end.)

Note: When adjusting the throttle lever angle, relative to

the rotor,hold the rotor at about half-way between the open and closed positions while loosening and tightening the fixing screw, otherwise the rotor, rotor guide screw,throttle stop screw or carburettor body may become burred and damaged.

SILENCER

The exhaust outlet of the silencer can be rotated to any desired position in the following manner:

Assembly screw

Exhaust pressure nipple

Loosen the locknut and assembly screw.

Set the exhaust outlet at the required position by rotating the rear part of the silencer.

Re-tighten the assembly screw, followed by the locknut.

NOTE : The standard expansion-chamber type silencer is

quite effective, but reduces power to some degree.

E-4010 Silencer

Cone baffle

Turn to requlred position

Exhaust outlet

Locknut

Reminder!

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.

FUEL TANK LOCATION

Suggested fuel tank capacities are listed opposite. These will allow 12-13 minute flights. Locate the fuel tank so that the top of the tank is 510mm (1/4-3/8") above the level of the needle-valve.

Be sure to use a pressurized fuel system by

• connecting the muffler pressure nipple to the ventpipe of the fuel tank.

50SX

Suggested Fuel Tank Capacities

approx 300cc

46FX

Attention to tank height

61FX 91FX

approx 350cc approx 450cc

Fuel level

10mm

GLOWPLUG

Since the glowplug and fuel combination used may have a marked effect on performance and reliability, it would be worthwhile to experiment with different plug types. Recommended O.S. plugs are Nos. 8, A5 and A3. Carefully install plug finger-tight, before final tightening with the correct size plug wrench.

The role of the glowplug

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.

Glowplug life

Particularly in the case of very high performance engines,

glowplugs must be regarded as expendable 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.

When to replace the glowplug

Apart from when actually burned out, a plug may need to be replaced because it no longer delivers its best performance, such as when:

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.

•

FUEL

Select, by practical tests, the most suitable fuel from among the best quality fuels available in your country for model use. For the best performance, a fuel containing 5% to 20% nitromethane is preferable. Lubricants may be either castor-oil or a suitable synthetic oil ( or a blend of both ) provided that they are always of top quality. For consistent performance and long engine life, it is essential to use fuel containing AT LEAST 18% lubricant by volume. Some fuels containing coloring additives tend to deteriorate and may adversely affect running qualities. Once a satisfactory fuel has been selected and used for a while, it may be unwise to needlessly change the brand or type. In any engine, a change of fuel may cause carbon deposits in the combustion chamber or on the piston head to become detached and lodged elsewhere, with the risk of this causing unreliable operation for a while. If, however, the adoption of a different fuel is unavoidable, check the engine for the first few flights on the new fuel, by temporarily reverting to the running-in procedure.

Reminder!

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.

PROPELLERS

Suggested propeller sizes are listed on page 15. The suitability of the prop depends on the size and weight of the model and type of flying. Determine the best size and type after the engine has been run in. Check the balance of the propeller before fitting it to the engine. Unbalanced propellers cause vibration and loss of power. Wooden propellers are to be preferred. Some nylon propellers are not strong enough to withstand the high power output of these engines and a thrown blade can be very dangerous.

50SX 40FX

46FX 61FX

91FX

11✕6~10,12✕6 10✕6,10.5✕6,11✕6~7

10.5✕6,11✕6~8,12✕6~7 12✕6~8,13✕6~7 15

RING

8,16✕6~8,17✕6

Sport

(3-blade)

Aerobatic

12✕7

11✕8~10,12✕7~9

(

tuned silencer used

12✕9~11

(

tuned silencer used

13✕11~13,14✕10~11

Reminder!

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.

MIXTURE CONTROLS

Two mixture controls are provided on these engines.

The Needle Valve (at rear of engine)

)

•

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 (carburetor)

•

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.

Type of Carburetor

50SX

46FX

40B

61FX 91FX

60C 60F

BEFORE STARTING

Tools, accessories, etc.

The following items are necessary for operating the engine.

1 Fuel

Model glowplug engine fuel of good quality, preferably containing a small percentage of nitromethane.

2 Glowplug

O.S. No.8 glowplug is fitted to the engine.

3 Propeller

Suggested size is 10x6(40FX), 11X6 (46FX), 12X6 (50SX, 61FX), or 15x8(91FX) .

4 Glowplug battery

The power source for heating the glowplug may be either a large heavy-duty 1.5volt dry cell, or preferably, a 2-volt rechargeable lead-acid cell (accumulator).

If a 2-volt cell is employed, use a resistance wire, as shown, to reduce applied voltage, otherwise element

1.5 volt heavy-duty dry battery

or 2 volt rechargeable lead-acid cell (at least 5Ah)

will overheat and burn out.

Warning (Very hot)

Never touch the nichrome wire while the battery is connected.

Resistance coil (nichrome wire)

Battery leads

Adjust applied voltage by changing the position of clip on resistance coil until glowplug element is glowing bright red.

5 Battery leads

Raise

voltage to

increase

brightness.

Lower voltage to

reduce brightness.

Battery leads

These are used to conduct current from the battery to the glowplug. Basically, two leads, with clips, are required, but, for greater convenience, twin leads with special glowplug connectors, as shown on the right, are commercially available.

6 Fuel tank

For installation in the model, a 300cc (10.6oz.) for 50SX and 40,46FX, a 350cc (12oz.) for 61FX, a 450cc (15.8oz.) for 91FX tank, is suggested.

7 Fuel bottle or pump

For filling the fuel tank, a simple, polyethylene "squeeze" bottle, with a suitable spout,is all that is required. Alternatively, one of the purpose-made manual or electric

Fuel bulb

Fuel pumps

fuel pumps may be used to transfer fuel directly from your fuel container to the fuel tank.

8 Electric starter and starter battery

Electric

Manual

Starter

An electric starter is recommended for starting.

9 Fuel can filter

Fit a filter to the outlet tube of your

12V Battery

Fuel Can Filter

refuelling container to prevent entry of foreign matter into the fuel tank.

10 Silicone tubing

This is required for the connection between the fuel tank and engine.

11 Plug wrench

Used for tightening glowplug. The O.S. long plug wrench is available as an optional accessory.

STARTING

Install appropriate propeller and tighten securely.

To facilitate electric starting, Install an O.S. solid aluminium alloy spinner-nut for centering the rubber drive insert of the starter. Alternatively, a good quality spinner, enclosing the propeller boss, may be used, but make sure that it is of precision-made and sturdy construction so that the spinner shell cannot loosen when the starter is used. Close the throttle.

For tightening glowplug

Fill the fuel tank. Do not allow fuel to overflow into

3. the silencer, otherwise the engine may become flooded and difficult to start.

Check that the needle-valve is closed. (Do not overtighten.) Now open the needle-valve counterclockwise to the starting setting:-

•

2 turns for 50SX,40,46,61FX

•

2 turns for 91FX

•

4 turns for 61FX when a tuned silencer is used.

Mark

Turn needle-valve clockwise to close (for leaner mixture)

Turn needle-valve counter-clockwise

to open (for richer mixture)

Open

5. Open the throttle approx. one-quarter.

(This is to avoid unnecessarily high r.p.m. when the engine starts.)

Fully closed position

1 4

Fully opened position

3 4

Set at this point

6. Connect battery leads to glowplug. Bring electric starter into contact with spinner-nut

or spinner and depress starter switch for one or two seconds. Repeat if necessary. When the engine starts, withdraw the starter immediately.

Attention : Do not choke the carburettor air intake when applying the starter. This could cause an excessive amount of fuel to be drawn into the cylinder which may initiate an hydraulic lock and damage the engine. If the engine does not start within 10 repeat applications of the starter, remove the glow-plug, check that it glows brightly and that the cylinder is not flooded with fuel. (To eject excess fuel, close needlevalve and apply starter with glowplug removed.) Then try again.

VERY IMPORTANT!

Before being operated at full power (i.e. at full-throttle and with the needle-valve closed to its optimum setting) the engine must be adequately run-in, otherwise there is a danger of it becoming overheated and damaged.

RUNNING-IN ("Breaking-in")

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. The process is as follows.

Install the engine with the propeller intended for

1. your model. Open the needle-valve to the advised starting setting and start the engine. If the engine stops when the glow plug battery disconnected, open the needle-valve to the point where the engine does not stop.Run the engine for one minute with the throttle fully open, but with the needlevalve adjusted for rich, slow "four-cycle"operation.

Now close the needle-valve until the engine speeds up to "two-cycle"operation and allow it to run for about 10 seconds, then reopen the needlevalve to bring the engine back to "fourcycle"operation and run it for another 10 seconds. Repeat this procedure until the fuel tank is empty.

Re-start and adjust the needle-valve so that the

3. engine just breaks into "two-cycle" from "fourcycle" operation, then make three or four flights, avoiding successive "nose-up" flights.

During subsequent flights, the needle-valve can be gradually closed to give more power. However, if the engine shows signs of running too lean, the next flight should be set rich. After a total of ten to fifteen flights, the engine should run continuously, on its optimum needle-valve setting, without loss of power as it warms up.

After the completion of the running-in adjust the carburetor at optimum setting referring to MIXTURE CONTROL VALVE ADJUSTMENT section and SUBSEQUENT READJUSTMENT section.

Optimum needle setting(1)

Slowly advance the throttle to its fully open position, then gradually close the needle-valve until the exhaust note begins to change. (4-cycle to 2-cycle) At this point, disconnect the battery from the glowplug, taking care that the battery leads or glowplug clip do not come into contact with the rotating propeller. If the engine stops when the battery is disconnected, close the needle-valve about 30˚ and restart.

Optimum needle setting(2)

As the needle-valve is closed slowly and gradually, the engine r.p.m. will increase and a continuous highpitched exhaust note, only, will be heard. Close the needle-valve 10-15˚ and wait for the change of r.p.m. After the engine r.p.m. increases turn the needlevalve another 10 -15˚ and wait for the next change of r.p.m. As the speed of the engine does not instantly change with needle-valve readjustment, small movements, with pauses between, are necessary to arrive at the optimum setting.

Needle-valve adjustment diagram

Clear, high-pitched two-stroke exhaust note

Intermittent, high-pitched two-stroke note superimposed on low "four-stroke" sound.

Disconnect battery leads from glowplug at about this point.

Exhaust note starts to change.

Note: Although this is a two-stroke engine it fires like a four-stroke at these rich needle-valve settings-i.e. ignition of the fuel charge takes place at every fourth stroke of the piston instead of at every second stroke.

Practical best(optimum) needle-valve setting

Maximum rpm



setting("Lean").

STARTING

"Rich" needle-valve

setting when starting

the engine.

The engine may stop if the battery leads are disconnected from the glowplug while the engine is running rich.

Note : This diagram is for reference

purposes only. Actual needle positions may differ from those shown.

To stop the engine, close the

• throttle completely to cut off fuel/air supply.

IDLING ADJUSTMENT CHART

Re-set the idling position at a little higher r.p.m.

Refer to the next section.

Engine stops.

Start the engine.

Make sure that the throttle is fully open.

Adjust the neede-valve.

Close the throttle gradually.

Find the idling position.

Fix the idling position.

Open the throttle fully.

Does the engine regain full power?

Continue running at high speed for 10 seconds.

Close the throttle.

Run at idling speed for 5 seconds.

Does the engine stop?

Apply full throttle.

Does the engine

regain full power immediately?

Yes.

No.

Yes.

Disconnect the battery leads at mid speed.

20-30˚ open from maximum r.p.m. setting.

The position where the lowest possible r.p.m. ,with steady running, is obtained.

Set the throttle opening by means of the throttle trim on the transmitter so that the lowest practical speed, without risk of the engine stopping,is obtained.

MIXTURE CONTROL VALVE ADJUSTMENT

With the engine running, close the throttle and allow it to idle for about five seconds, then open the throttle fully. If, at this point, the engine is slow to pick up and produces an excess of exhaust smoke, the mixture is too rich. Correct this condition by turning the Mixture Control Screw clockwise 15-30˚. If the mixture is excessively rich, engine rpm will become unstable: opening the throttle will produce a great deal of smoke and rpm may drop suddenly or the engine may stop. This condition may also be initiated by excessively prolonged idling. If,on the other hand, the mixture is too lean, this will be indicated by a marked lack of exhaust smoke and a tendency for the engine to cut out when the throttle is opened. In this case, turn the Mixture Control Screw counter-clockwise 90˚to positively enrich the idle mixture, then turn the screw clockwise gradually until the engine regains full power cleanly when the throttle is reopened. Carry out adjustments patiently until the engine responds quickly and positively to the throttle control.

Note: Mixture Control Valve adjustments should

be made in steps of 15-30˚ initially, carefully checking the effect, on throttle response, of each small adjustment.

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. Its basic setting can be re-established as follows: Close the throttle rotor gradually from the fully opened position until it is just fully closed. (Do not turn further.) Then, screw in the Mixture Control Screw until it stops. Now unscrew the Mixture Control Screw as indicated below.

61FX 91FX

approx approx2

50SX 40 · 46FX

approx1 turn

turns

SUBSEQUENT STARTING PROCEDURE

Once the optimum needle-valve setting has been established (see page 19, Needle-valve adjustment diagram) the procedure for starting may be simplified as follows.

Open the needle-valve one half-turn (180°) from

1. the optimum setting.

Set the throttle one-quarter open from the fully

2. closed position, energize the glowplug and apply the electric starter. When the engine starts, reopen the throttle and re-adjust the needle-valve to the optimum setting.

Note: When re-starting the engine on the same day, provided that atmospheric conditions have not changed significantly, it may be practicable to restart the engine on its optimum(running) setting.

SUBSEQUENT READJUSTMENT

Once the engine has been run-in and the controls properly set up, it should be unnecessary to alter the mixture settings; except to make minor adjustments to the Needle-Valve occasionally, to take account of variations in climatic conditions. The use of a different fuel, however, particularly one containing more, or less, nitromethane and/or a different type or proportion of lubricating oil, is likely to call for some readjustment of the Needle-Valve. Remember that, as a safety measure, it is advisable to increase the Needle-Valve opening by an extra half-turn counter-clockwise, prior to establishing a new setting. The same applies if the silencer type is changed. A different silencer may alter the exhaust pressure applied to the fuel feed and call for a revised NeedleValve setting. The use of a different glowplug may also require compensating carburetor readjustments.

CARBURETOR CLEANLINESS

The correct functioning of the carburetor depends on its small fuel orifices remaining clear. The minute particles of foreign matter that are present in any fuel, can easily partially obstruct these orifices and upset mixture strength so that engine performance becomes erratic and unreliable. O.S.'Super-Filters'(large and small ) are available, as optional extras, to deal with this problem. One of these filters, fitted to the outlet tube inside your refueling container, will prevent the entry of foreign material into the fuel tank. It is also recommended that a good in-line filter be installed between the tank and needle-valve. Do not forget to clean the filters regularly to remove dirt and lint that accumulate on the filter screen. Also, clean the carburetor itself occasionally.

ENGINE CARE AND MAINTENANCE

At the end of each operating session, drain out any

1. fuel that may remain in the fuel tank.

Next, energize the glowplug and try to restart the

2. engine to burn off any fuel that may remain inside the engine. Repeat this procedure until the engine fails to fire. Remove the glowplug and eject any residue by rotating the engine with an electric starter for 4 to 5 seconds while the engine is still warm.

Finally, inject some after-run oil into the engine.

3. Rotate the engine a few times by hand, to make sure that it is free, and then with an electric starter for 4 to 5 seconds to distribute the oil to all the working parts.

Note: Do not inject after-run oil into the carburetor as this may cause the O-ring inside the carburettor to deteriorate.

These procedures will reduce the risk of starting difficulties and of internal corrosion after a period of storage.

EXPLODED VIEW (50SX)

C.M3✕15

C.M2.6✕18

q-1

i-1

i-10

✽ Type of screw

C…Cap Screw F…Flat Head Screw N…Round Head Screw S…Set Screw

i-8

i-9

i-6

i-5

i-7

i-3

C.M3✕8

S.M3

i-2

i-4

ENGINEN PARTS LIST (50SX)

No.

Code No.

25204010

25203100

25303400

25203200

25206000

25217000

25205000

25681010

25281140

23981700

23210007

23209003

27708010

-1

27708200

46120000

26731002

25201000

26730005

25202010

25214000

25207010

-1

25207100

-2

24081970

-3

24981837

-4

26381501

-5

46181940

-6

46181941

-7

26711305

-8

46181950

-9

22881300

-10

22681953

25613000 71608001 25425000 22681957 25425310 25425400

Cylinder Head Cylinder Liner Piston Ring Piston Piston Pin Piston Pin Retainers Connecting Rod Carburetor (Type 40B) Carburetor Spacer

Carburetor Retainer

Propeller Nut

Propeller Washer Drive Hub

Woodruff Key Thrust Washer Crankshaft Ball Bearing (F) Crankcase Crankshaft Ball Bearing (R) Crankshaft

Gasket Set

Cover Plate Assembly

Cover Plate Body Needle

"O"

Set Screw

Needle Valve Holder Assembly

Needle Valve Holder Ratchet Spring Fuel Inlet

Plug Screw Fuel Outlet

Screw Set Glow Plug No.8 873 Silencer Assembly

Pressure Fitting

Assembly Screw

Retaining Screw (2pcs.)

Specifications are subject to alteration for improvement without notice.

Description

Ring

EXPLODED VIEW (40,46FX)

C.M3X15

N.+M3.5X6

r-2

r-1

6-1

-2

✽Type of screw

C…Cap Screw F…Flat Head Screw N…Round Head Screw S…Set Screw

C.M3X8

S.M3X3

r-7

r-4

r-6

r-5

r-3

ENGINEN PARTS LIST (40,46FX)

No. Description

Cylinder Head

Cylinder & Piston Assembly

Piston Pin

Piston Pin Retainer

Connecting Rod

Carburetor (Type 40B)

-1

Carburetor Rubber Gasket

-2

Carburetor Retaining Screw (2pcs.)

Propeller Nut

Propeller Hub

Drive Hub

Thrust Washer

Crankshaft Ball Bearing (F)

Crankcase

Crankshaft Ball Bearing (R)

Crankshaft

Gasket Set

Cover Plate Assembly

-1

Cover Plate Body

-2

Fuel Outlet

-3

Needle

-4

"O"

Ring

-5

Set Screw

-6

Needle Valve Holder Assembly

-7

Ratchet Spring

Screw Set

873 Silencer

Pressure Fitting Assembly Screw Retaining Screw (2pcs.)

Specifications are subject to alteration for improvement without notice.

40FX 46FX

25604000 25603000 25406000 24817100 25305002 25681010 46215000 25081700 23210007 23209003 25608000 46120000 26731002 25601000 26730005 25602020 25614000 25607000 25607100 22681953 22681980 24981837 26381501 27381940 26711305 25613000 25425000 22681957 25425310 25425400

Code No.

25604010 25603010 24806301 24817100 25305002 25681010 46215000 25081700 23210007 23209003 25608000 46120000 26731002 25601100 26730005 25602020 25614010 25607000 25607100 22681953 22681980 24981837 26381501 27381940 26711305 25613000 25425000 22681957 25425310 25425400

EXPLODED VIEW (61FX)

C.M3✕15

6-1

6-2

r-5

r-3

r-4

C.M3.5

✽ Type of screw

N.M3.5✕6

r-1

r--10

r-2

r-9

r-11

r-7

r-6

C…Cap Screw F…Flat Head Screw N…Round Head Screw S…Set Screw

C.M3✕8

r-8

ENGINEN PARTS LIST (61FX)

No.

Code No.

27754000

27753000

26606008

27917000

26025000

27783000

-1

46215000

-2

25081700

45010002

28009002

27758000

29320000

27731000

27751000

29030001

27752000

27914000

27757000

-1

27757100

-2

22681953

-3

27757010

-4

46181950

-5

27757030

-6

22681980

-7

24981837

-8

26381501

-9

27783940

-10

21281800

-11

26711305

27913000 71608001 26028000 22681953 26028100 26625210

Cylinder Head Cylinder & Piston Assembly

Piston Pin Piston Pin Retainer Connecting Rod Carburetor (Type 60C)

Carburetor Rubber Gasket

Carburetor Retaining Screw Propeller Nut Propeller Washer

Drive Hub Thrust Washer Crankshaft Ball Bearing (F) Crankcase

Crankshaft Ball Bearing (R)

Crankshaft

Gasket Set

Cover Plate Assembly

Cover Plate Body Fuel Outlet Fuel Inlet Assembly

Fuel Inlet Inlet Holder Needle

"O"

Ring Set Screw Needle Valve Holder Assembly

"O"

Ring Ratchet Spring

Screw Set Glow Plug No.8 E-4010 Silencer

Pressure Fitting Assembly Screw Retaining Screw (2pcs.)

Specifications are subject to alteration for improvement without notice.

Description

EXPLODED VIEW (91FXRING)

C.M3✕15

8-2

N.M3.5✕6

-1

t-9

-1

t-6

t-8

t-1

-10

t-5

✽ Type of screw

C…Cap Screw F…Flat Head Screw N…Round Head Screw S…Set Screw

t-7

t-3

C.M3.5✕10

S.M3

t-4

t-2

ENGINE PARTS LIST (91FX RING)

Code No.

No.

29504000

29503100

29503400

29053200

45406000

27917000

29505000

29581000

-1

29015019

-2

25081700

45910100

29508000

-1

29008219

46120000

26731002

29501000

29030001

29502000

29514000

29507000

-1

29507100

-2

24081970

-3

24981837

-4

26381501

-5

46181940

-6

46181941

-7

26711305

-8

46181950

-9

22881950

-10

22681953

29513000 71608001 29525000 29525100 26625210 22681957 72200080

Cylinder Head Cylinder Liner

Piston Ring Piston Piston Pin Piston Pin Retainers (2) Connecting Rod Carburetor (Type 60F)

Carburetor Gasket

Carburetor Retaining Screw (2pcs.) Propeller Lock Nut Set Drive Hub

Woodruff Key

Thrust Washer Crankshaft Ball Bearing (F) Crankcase Crankshaft Ball Bearing (R) Crankshaft

Gasket Set Cover Plate Assembly

Cover Plate Body Needle

"O"

Ring Set Screw Needle Valve Holder Assembly Needle Valve Holder Ratchet Spring Fuel Inlet Plug Screw Fuel Outlet

Screw Set Glow Plug No.8 E-4020 Silencer Assembly

Assembly Screw Retaining Screw (2pcs.) Pressure Fitting

Needle Valve Extension Cable Set

Specifications are subject to alteration for improvement without notice.

Description

No.

1-1 1-2

2-1

1-1

1-2

Code No.

22781401 22781420 22781411

27783600 22781800

25681200

26781506

25681100

25681620

22681953

46215000

25081700

CARBURETOR 40B (50SX,40,46FX)

2-1

N.+M3.5X6

Description

Throttle Lever Assembly Throttle Lever Fixing Screw Throttle Lever Mixture Control Valve "O"Ring Carburettor Rotor Rotor Spring Carburettor Body Throttle Stop Screw (W/Spring) Fuel Inlet (W/Washer) Carburettor Gasket Carburettor Fixing Screw

1-2

1-1

✽ Type of screw

C…Cap Screw F…Flat Head Screw N…Round Head Screw S…Set Screw

No.

Code No.

22781401

1-1

22781411

1-2

22781420

27783600

2-1

22781800

27783200

26781506

27783100

25681620

22681953

46215000

25081700

CARBURETOR 60C (61FX)

2-1

N.+M3.5X6

Description

Throttle Lever Assembly Throttle Lever Throttle Lever Fixing Screw Mixture Control Valve "O"Ring Carburettor Rotor Rotor Spring Carburettor Body Throttle Stop Screw (W/Spring) Fuel Inlet (W/Washer) Carburetor Gasket Carburetor Retaining Screw

CARBURETOR 60F (91FXRING)

N.+M3✕6

-1

3-2

N.M3.5✕6

✽ Type of screw

C…Cap Screw F…Flat Head Screw N…Round Head Screw S…Set Screw

Code No.

No.

27881400

29581200

45582300

3-1

46066319

3-2

24881824

29581100

45581820

22681953

29015019

25081700

Description

Throttle Lever Assembly Carburettor Rotor Mixture Control Valve Assembly "O" Ring (L) "O" Ring (S) Carburettor Body Rotor Guide Screw Fuel Inlet (W/Washer) Carburetor Gasket Carburetor Retaining Screw (2pcs.)

Specifications are subject to alteration for improvement without notice.

O.S. GENUINE PARTS & ACCESSORIES

O.S. GLOW PLUGS

■

No.8

(71608001)

(71605100)

(71605300)

SILENCER EXTENSION

■

ADAPTORS

25425600 26625340 26625500

Type of Engine

50SX. 40.46FX(873

61FX(E-4010).91FX(E-4020

Length 35mm

61FX(E-4010).91FX(E-4020

Code No.

SPINNER NUT

■

Code No.

23024009 45024000

Silencer

)

LONG PROPELLER NUT SETS

■

Type of Engine

Size

)

50SX. 40. 46FX

1/4"-28(L

5/16"-24

61FX. 91FX

SILENCER EXHAUST

■

ADAPTORS

)

Code No. Type of Engine¡Silencer

25425500 26625410

50SX. 40.46FX(873)

61FX(E-4010).91FX(E-4020

Code No. Size Type of Engine

73101000 73101010

PROPELLER NUT SETS

■

1/4"-28

5/16"-24

50SX. 40. 46FX

61FX. 91FX

FOR TRUTURN SPINNERS

(73101020)

)

For 50SX. 40.46FX

EXHAUST

■

HEADER PIPE

(72101230)

For 61FX

91FX

SUPER SILENCERS

■

Code No.

25425020

26028010

Size

873S

E-4010S

Type of Engine

50SX. 40¡46FX

61FX

O.S. SILICONE

■

TUBE ASSEMBLY

Type of Engine

Code No.

72105337 72101338

61FX.91FX

40.46FX

SUPER FI LTER

■

(72403050)

■

LOCK WASHER

Code No.

Size

55500002

55500003

(10Sets)

Type of Engine

50SX. 40.46FX

61FX.91FX

T-4010 TUNED SILENCER

■

(72101120)

For 61FX

LONG SOCKET WRENCH

■

WITH PLUG GRIP

(71521000)

BUBBLE ELIMINATING

■

TANK WEIGHT

(71531000)

MAX-50SXRING

SPECIFICATIONS

Displacement

■

Bore

■

Stroke

■

Practical R.P.M.

■

Power output

■

Weight

■

Dimensions(mm)

8.17 cc (0.499 cu.in.

22.0mm (0.866 in.

21.5mm (0.847 in.

2,000

1.8 bhp / 17,000 r.p.m. 390g (13.76 oz.

) )

20,000 r.p.m.

)

17.5

)

37.7

UNF1/4-28

36 52

60.7 25 121

70.5

18.3

7.5

THREE VIEW DRAWING

MAX

40FX

SPECIFICATIONS

Displacement

■

Bore

■

Stroke

■

Practical R.P.M.

■

Power output

■

Weight

■

MAX

46FX

SPECIFICATIONS

Displacement

■

Bore

■

Stroke

■

Practical R.P.M.

■

Power output

■

Weight

■

6.47 cc (0.395 cu.in.

20.5mm (0.807 in.

19.6mm (0.772 in.

17,000 r.p.m.

2,000

1.36 bhp / 16,000 r.p.m. 386g (13.6 oz.

7.45 cc (0.455 cu.in.

22.0mm (0.866 in.

19.6mm (0.772 in. 2,500

1.62 bhp / 16,000 r.p.m. 375g (13.2 oz.

17,000 r.p.m.

)

17.5

) ) )

)

) )

UNF1/4-28

36.3

60.5

19.5

Dimensions(mm)

MAX

61FX

SPECIFICATIONS

Displacement

■

Bore

■

Stroke

■

Practical R.P.M.

■

Power output

■

Weight

■

9.95 cc (0.607 cu.in.

24.0mm (0.945 in.

22.0mm (0.866 in.

2,000

1.9 bhp / 16,000 r.p.m. 550g (19.42 oz.

) )

17,000 r.p.m.

)

ø4.2

)

ø4.2

UNF5/16-24

100.5

43 61

66.5

29.1

Dimensions(mm)

MAX

91FX

RING

SPECIFICATIONS

Displacement

■

Bore

■

Stroke

■

Practical R.P.M.

■

Power output

■

Weight

■

14.95 cc (0.912 cu.in.

27.7mm (1.091 in.

24.8mm (0.976 in.

2,000

2.8 bhp / 15,000 r.p.m. 550g (19.42 oz.

) )

16,000 r.p.m.

)

43.5

24.7

42.6 61

UNF5/16-24

4-φ4.2

66.5 29.5

81.521.5 103

Dimensions(mm)

6-15 3-Chome Imagawa Higashisumiyoshi-ku Osaka 546-0003, Japan

URL : http://www.os-engines.co.jp

TEL.(06)6702-0225

FAX. (06) 6704-2722

110101

O.S. Engines 50SX User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual