O.S. Engines 65LA 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
ABOUT YOUR O.S. ENGINE

INTRODUCTION

INSTALLATION OF THE ENGINE

I

NSTALLATION OF SILENCER

NEEDLE-VALVE LOCATION

BEFORE STARTING
ADVICE ON SELECTION OF FUEL,

GLOW PLUG & PROPELLER

STAR TING THE ENGINE

RUNNING-IN (Breaking-in)

2~6

10

~

12

10

12~14

14

~

22

23

CARBURETTOR

CARBURETTOR AIR-BLEED
ADJUSTMENT

7

TROUBLE SHOOTING WHEN THE

8

ENGINE FAILS TO START

9

CARE AND MAINTENANCE

OPTIONAL PARTS & ACCESSORIES

ENGINE EXPLODED VIEW &
PARTS LIST

CARBURETTOR EXPLODED
VIEW & PARTS LIST

THREE VIEW DRAWING

1

23

26

30

37

~

24

25

~

27

28

29

~

35

36

~

38

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.

Fit 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, 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 carburettor.

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 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!

6

INTRODUCTION

THE MAX-40LA, 46LA and 65LA have been developed
to meet the requirements of beginners and sport flyers.
Of modern design and having a separate needle-valve
unit mounted at the rear, where manual adjustment is
safely remote from the rotating propeller, they offer the
advantages of reliability and easy handling, at lower
cost. Like all O.S. engines they are built to standards
of engineering excellence that have evolved through
more than 60 years' experience in the design and
production of model internal-combustion engines.
Advanced modern precision machinery, top quality
materials and the efforts of highly skilled craftsmen and
technicians are combined to ensure a continuation of
the levels of performance, durability and reliability for
which O.S. is world famous.
The MAX-46LA has a larger cylinder diameter , but both
the 40LA and 46LA engines have the same external
dimensions.

The 'midnight blue' external finish may be
decolorized by very high surface temperature or
by certain solvents. Such decolorization does not
affect engine perfor-mance, however.

Cylinder head

Carburettor

Propeller nut

Crankshaft

Fuel inlet

Drive Hub

Propeller washer

Glowplug

Needle valve

Fuel outlet

Cover Plate

Silicone Tube

Crankcase

Connect the short length of fuel tubing supplied
securely between the fuel outlet and the fuel inlet. In
the event of the tube becoming damaged, it should be
replaced with a suitable length of best quality 5mm
ODX2mm ID silicone tubing. Use similar material to
connect the fuel inlet nipple to the fuel tank.

7

INSTALLATION

Installation in the model

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

At least
12mm(1/2")

At least
12mm(1/2")40-46LA
15mm(5/8")65LA

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

CORRECT

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

Rigid hardwood
(e.g. maple)

INCORRECT

How to fasten the mounting screws.

3mm steel nuts
(40-46LA)
4mm(65LA)

Spring washer or
lock washer

Tighten second nut firmly
down onto first nut.

Tighten this nut first.

Steel washer

3.5mm steel screw
(40-46LA)
4mm(65LA)

Hardwood mounting beams

3mm steel Allen screw

Spring washer

Hardwood such as
cherry or maple.

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

Top surfaces
are not in the
same plane.

Engine does
not seat firmly.

O.S. radial motor mount
(cast aluminum)

8

NEEDLE-VALVE EXTENSION

The needle-valve supplied with these engines is
designed to incorporate an extension so that, when
the engine is enclosed within the fuselage, the
needle-valve may be adjusted from the outside.
Cut a commercially available rod to the required
length, bend one end to an L shape, insert it into
needle's center hole and secure it by tightening the
set-screw in the needle-valve knob with 1.5mm. Allen
key.

INSTALLATION OF SILENCER

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

1) Loosen the locknut and assembly screw.

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

3) Re-tighten the assembly screw, followed by the
locknut. The standard silencer is quite effective but
reduces power to some degree.

Assembly screw

Exhaust pressure nipple

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.

Cone baffle

Turn to requlred position

Exhaust outlet

NEEDLE-VALVE LOCATION

As delivered from the factory, the MAX-40LA, 46LA &
65LA have the needle-valve assembly installed
vertically. However, if more convenient for a particular
installation, the needle-valve may be reinstalled
horizontally.
The procedure for relocating the needle-valve is as
follows:

9

Locknut

Remove the two cover-plate screws which secure

1.
the needle-valve assembly bracket, then carefully
remove the two screws by which the needle-valve
unit is attached to the bracket.

2.

Rotate the needle-valve unit through 90˚ and re­attach it to the bracket in the required position (see
sketch right).

Note:
As self-tapping screws are used for unit
attachment, screw them in carefully so that screw
threads match those of the unit body precisely.

3.

Finally, secure the complete assembly to rear cover
plate as before.

Needle Valve unit

Cover plate fitting holes

Needle-Valve
Assembly Bracket

Needle Valve unit attachment screws

Vertical position
(Factory position)

Horizontal position

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. (See
"Advice on selection of fuel, glowplug and propeller")

2 Glowplug

O.S. A3 glowplug is installed in the engine.

3 Propeller

Suggested size is 11X5 (40LA), 11X6 (46LA), or 12X6
(65LA).

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 the element

1.5 volt heavy-duty
dry battery

10

will overheat and burn out.

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

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.

Raise

voltage to

increase

brightness.

Lower voltage to

reduce brightness.

5 Plug wrench

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

6 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.

7 Fuel tank

For installation in the model,
a 200cc(7oz.) for 40.46LA, or
a 350cc(12oz.) for 65LA, is
suggested.

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

9 Fuel can filter

Fit a filter to the outlet tube of
your refuelling container to
prevent entry of foreign
matter into the fuel tank.
(Refer to of STARTING

4

THE ENGINE section.)

11

Fuel bulb

Battery leads

Fuel pumps

Electric

Fuel Can Filter

12V Battery

For tightening
glowplug

Manual

Starter