O.S. Engines 120AX User Manual

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		MIXTURE CONTROLS, STARTING	25-28
	ABOUT YOUR O.S. ENGINE	2-6
	NOTES WHEN APPLYING AN ELECTTRIC STARTER	7	RUNNING -IN, IDLING ADJUSTMENT CHART	29-32
	ABOUT THE ENGINE	8	MIXTURE CONTROL VALVE ADJUSTMENT,	33
			REALIGNMENT OF MIXTURE CONTROL VALVE
	BEFORE STARTING	9-12	SUBSEQUENT STARTINGPROCEDURE,
	GLOWPLUG	13	SUBSEQUENT READJUSTMENT	34
	BASIC ENGINE PARTS	14	CARBURETOR CLEANLINESS	35
	INSTALLATION	15-16	TROUBLE SHOOTING WHEN THE	36-37
			ENGINE FAILS TO START
	INSTALLATION OF SILENCER & ADAPTERS	17-19	CARE AND MAINTENANCE	38-39
	FUEL TANK LOCATION	20-21	ENGINE EXPLODED VIEWS & PARTS LIST	40-41
	NEEDLE-VALVE EXTENSION,		CARBURETOR EXPLODED VIEWS& PARTS LIST	42-43
	THROTTLE LINKAGE	22
	PROPELLER & SPINNER ATTACHMENT	23-24	GENUINE PARTS & ACCESSORIES	44
			THREE VIEW DRAWING	45-46

1

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.

2

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.

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.

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.

4

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.

5

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 glowplugignition 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!

6

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 getting into your eyes.

7

ABOUT THE ENGINE

Two versions are available, the one is without silencer, extension adaptor and 90 degree adaptor and the other is with all of them.

This is a high performance two stroke engine designed for sport and scale models.

Crankcase and cylinder head are of aeroshape design which give advantage of light weight, compact size.

The new 70D carburetor needlevalve assembly has now been angled backward for safety.

New E-5020 silencer (POWER BOX) develops very effective muffling.

Also, the compact body enables it to be fit with in most cowls.

Extension adaptor and 90 degree adaptor offer various silencer installations.

8

STANDARD ACCESSOIES

Glow Plug No.8

(suppplied with the engine)

Needle Valve Extension Cable Set

E-5020 Silencer Extention

Adapter

Silencer Extention Adapter

Retaining Screw (M4x90 2pcs.)

E-5020 Silencer 90 Adapter

Silencer 90 Adapter Retaining

Screw (M4x20 2pcs.)

E-5020 Silencer Assembly

Silencer Retaining Screw (M4x45 2pcs.)

BEFORE STARTING

Tools, accessories, etc.The following items are necessary for operating the engine.

Propellers

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,

props than those shown in the table may be used, but remember that speed the propeller noise will increase if blade tip is raised, due to higher rpm or if a larger-diameter/lower-pitched prop is used.

Sport	15x10-12, 16x8-10

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.

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.

Spinner

Since the 120AXRING 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.

9

FUEL

The 120AXRING 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. 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.

10

GLOWPLUG IGNITER

Commercialy available handy glowplug heater in which the glowplug battery and battery leads are integrated.

FUEL PUMP
Alternatively,	one of	the
purpose-made manual		or
		Manual
electric fuel pumps may be
used to transfer fuel directly
from your fuel container to
the fuel tank.		Electric
Electric Starter and
Starter Battery
Required when starting
the engine.	12-Volt lead-acid battery

Electric Starter

O.S. Super Filter (Fuel Can Filter)

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.

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.

Fuel Tank

A fuel tank of approximately 350cc capacity is suggested. This allows around 10-12 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.

GLOW PLUG

O.S. No.8 glowplug is supplied with the engine.

O.S. Non-Bubble Weight

To prevent the pickup from adhering to the tank wall under suction and restricting fuel flow, slots may be filed I the end of the weight. Alternatively, O.S. Non-Bubble Weight is available as an optional extra.

Fuel Filter

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.

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.

11

TOOLS

HEX Screwdriver

Necessary for engine installation. 1.5mm, 2mm, 2.5mm, 3mm

Phillips Screwdriver

No.1, No.2, etc.

SCREWDRIVER

Necessary for carburetor adjustments. No.1, No.2, etc

Socket Screwdriver

5.5mm, 7mm, 8mm

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.

8mm

End Wrenches

8mm, 12mm, 14mm, etc.

Needle Nose Pliers

12

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. An O.S. No.8 glowplug is supplied with the engine.

Recommended O.S. plugs are the No.8 and A5. 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 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.

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.

13

BASIC ENGINE PARTS

	E-5020 Silencer Extention Adapter
E-5020 Silencer	Glowplug
	Cylinder head

Carburetor Type 70D
Propeller washer	Cover Plate
Propeller nut	Beam Mount
Propeller Locknut	Crankcase
Crankshaft	Drive Hub

14

INSTALLATION

Because the 120AXRING is a powerful, large-displacement, single-cylinder engine, 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. Use at least 4mm steel screws, such as Allen type, with locknuts, for bolting the engine to the bearers.

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

CORRECT

			Side view
Front view

Top surfaces are in the same plane.

INCORRECT

	Top surfaces are not					Opposite beam
	in the same plane.
						Top surfaces are not in the
						same plane.
	Re-align the surfaces					Engine does not rest firmly.
	as necessary

15