O.S. Engines FS-40S 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,BASIC ENGINE PARTS
INSTALLATION
INSTALLATION OF CHOKE ROD, NEEDLE VALVE

EXTENSION, EXHAUST PIPE ADJUSTMENT(FS-26S)
SILENCER,

LINKAGE OF THROTTLE LEVER
BEFORE STARTING
FUEL AND PRESSURE LINES

ADVICE ON SELECTION OF FUEL,
GLOEPLUG & PROPELLER

STARTING THE ENGINE

2~6

11~12

13~14

~

15

22

~

25~26
27~29

32~35

21
23
24

30
31

36
37
38

RUNNING -IN
CARBURETOR

7

CARBURETOR AIR-BLEED ADJUSTMENT

8

TROUBLE SHOOTING WHEN THE
ENGINE FAILS TO START

9

VAL VE ADJUSTING

10

12

21

CARE AND MAINTENANCE
THREE VIEW DRAWING
ENGINE EXPLODED VIEW
CARBURETOR EXPLODED VIEW

& PARTS LIST
GENUINE PARTS & ACCESSORIES
MEMO

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, 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 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 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 FS Series engines are up-to-date
overhead-valve four-stroke-cycle engines
for model aircraft use and are the outcome of
a long period of technical development. The
FS Series engines are produced by the
world's oldest and largest model engine
manufacturing company; a company which
also pioneered the quantity production of
model four-cycle engines.

Accessories

FS-26S

•Silencer Body

•Choke rod

•Silicone tubing

INSTALLING THE GLOWPLUG

Install washer on glowplug and
insert carefully into cylinder­head, making sure that it is not
cross-threaded before tightening
firmly.

FS-40S

•Silencer Assembly

•Choke rod

•Silicone tubing

Glow plug

Washer

BASIC ENGINE PARTS

Glow plug

Silencer

Carburetor

Fuel inlet

Choke valve

Breather nipple

7

Rocker Cover

Drive Hub

Crankcase

Cover plate

Exhaust pipe

Propeller nut

Propeller
Washer

INSTALLATION

Installation in the model

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

At least 12mm
(1/2") for FS-26S

At least
15mm(19/32") for FS-40S

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
for FS-26S

3.5mm steel nuts
for FS-40S
Spring washer or
lock washer

3mm steel screw
for FS-26S

3.5mm steel screw
for FS-40S

Tighten second nut firmly
down onto first nut.

Tighten this nut first.

Steel washer

Hardwood mounting beams

3mm steel Allen screw
for FS-26S

3.5mm steel Allen screw
for FS-40S

Spring washer

Hardwood such as
cherry or maple.

Front view

Top surfaces are in
the same plane.

Side view

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 rest firmly.

O.S. radial motor mount
(cast aluminum)

8

INSTALLATION OF CHOKE ROD

The FS Series engines are equipped with self­reopening choke valves.
Cut the choke rod (supplied) to the length indicated,
then secire the rod by tightening the set screw, using

1.5mm Allen wrench (supplied), after installing the
engine.

Releasing the
choke rod allows
the choke valve

approx.
7mm

to open.

Frame sides
of fuselage

approx.
2mm

Choke rod

Choke rod

1.5mm
Allen key

Set-screw

NEEDLE VALVE EXTENSION

The needle-valve supplied with this engine is
designed to incorporate an extension so that, when
the engine is enclosed within the fuselage, the
needle-valve may be adjusted from the outside. Cut
the L-shaped rod supplied to the required length,
insert it into needle's centre hole and secure it by
tightening the set-screw in the needle-valve knob with

1.5mm. Allen key supplied.

1.5mm Allen key

Set-screw

EXHAUST PIPE ADJUSTMENT(FS-26S)

The direction of the exhaust pipe may be altered in
accordance with individual installation requirements.
The angle is easily adjusted by loosening the nut that
secures the exhaust pipe to the culinder head. Use
the 10mm spanner supplied. Recheck the tightness of
the nut after the engine has been run, but take care
not to touch the exhaust-pipe as it becomes very hot.

9

SILENCER

The FS-26S and FS-40S are supplied with silencers
as standard equipment.

Installation for FS-26S

Slide the silencer over the exhaust pipe, and secure it
with two set-screwssupplied with the silencer. Re­check tightness of screws when engine is hot.

Installation for FS-40S

Screw the exhaust header pipe into the exhaust port
until it "bottoms", then unscrew it just sufficiently to
achieve the required exhaust outlet angle. Secure the
pipe in this position by tightening the locknut firmly
against the cylinder head with the wrench supplied.
Then, screw the silencer onto the end of the header
pipe and tighten locknut firmly. Re-check tightness of
locknuts when engine is hot.

LINKAGE OF THROTTLE LEVER

First, ensure that the throttle rotor is fully closed when
the throttle-lever is in the closed position. Adjust rotor
stop screw if necessary. Then couple the lever to the
throttle-servo so that the rotor is fully closed when the
transmitter throttle stick and trim lever are in the fully
retarded 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. Type F glowplug is installed in the engine.

3 Propeller

Suggested propellers are shown in the ADVICE ON
SELECTION OF FUEL & PROPELLER section.

10

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.

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.

Battery leads

7 Fuel tank

For installation in the model, a 120cc(4.2oz.)
for FS-26S, a 150cc(5oz.) for FS-40S tank is
suggested.

8 Fuel bottle or pump

For filling the fuel tank, a simple,

Fuel bulb

Fuel pumps

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.

11

For tightening
glowplug

Manual

Electric