O.S. Engines FL-70 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
ENGINE CONSTRUCTION
NOTES WHEN APPLYING AN ELECTTRIC STARTER
INTRODUCTION
BEFORE STARTING
ENGINE PARTS NAME
INSTALLATION
SILENCER & EXHAUST HEADER PIPE INSTALLATION
FUEL TANK & LINES
THROTTLE LINKAGE, NEEDLE-VALVE EXTENSION
PROPELLER & SPINNER ATTACHMENT
GLOWPLUG
2-6
10-13
15-16
18-20
22-23
TYPE 60W CARBURETOR, STARTING
RUNNING -IN, CARBURETOR
7
CARBURETOR AIR-BLEED ADJUSTMENT
8
TROUBLE SHOOTING WHEN THE
9
ENGINE FAILS TO START
14
17
21
24
VALVE ADJUSTING
HOW TO SET THE CAMSHAFT TIMING
CARE AND MAINTENANCE
ENGINE EXPLODED VIEWS & PARTS LIST
CARBURETOR EXPLODED VIEWS
& PARTS LIST
GENUINE PARTS & ACCESSORIES
THREE VIEW DRAWING
25-27
27-30
31
32-33
34
35
36-37
38-39
40-41
42-43
44
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.
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.
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
Model engine fuel is also highly
flammable. Keep it away fr om 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. 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
NOTE
ENGINE CONSTRUCTION
With this engine, the piston will
feel tight at the top of its stroke
(TDC) when the engine is cold.
This is normal.
The cylinder bore has a slight
taper.
The piston and cylinder are
designed to achieve a perfect
running clearance when they
reach operating temperature.
Near TDC
Cylinder Liner
Crankshaft
Slight taper
When the engine is cold.
7
Piston
When the engine is hot.
NOTES WHEN APPL YING
AN ELECTRIC STARTER
Do not over-prime. This could
cause 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 coming
into your eyes.
8
INTRODUCTION
The FL-70 is an air-cooled, overheadvalve four stroke engine for model aircraft
use. This engine is suitable for trainer,
sport and scale models.
This engine reduces maintenance by
incorporating the first O.S. ringless
piston/liner assembly. Also, a sealed front
bearing prevents oil leaks. The engine is
fitted with the new easy-to use O.S. 60W
airbleed carburetor. This engine is
designed so that more R/C pilots, from
hobby beginners to skilled Sunday fliers
may enjoy the performance advantages
of four stroke engines – greater fuel
economy, higher torque, lower noise and
realistic sound.
Please note that this engine is not supplied
with any tools (e.g. Allen keys, wrenches, etc.)
STANDARD ACCESSOIES
Glow Plug Type F
(included with the engine)
F-4030 Silencer Assembly
T Nipple
9
BEFORE STARTING
Tools, accessories, etc.The following items are
necessary for operating the engine.
Items necessary for starting
GLOW PLUG
O.S. Type F glowplug is installed in the
engine.
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
electric fuel pumps may be used
to transfer fuel directly from your
fuel container to the fuel tank.
Manual
Electric
FUEL
The FL-70 should be operated on a methanol based
fuel containing not less than 20% (volumetric) castor
oil, or a top quality synthetic lubricant (or a mixture of
both), plus a small percentage (5-15%) of
nitromethane for improved flexibility and power. (The
carburetor is adjusted 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
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.
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.
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.
Fuel Tank
A fuel tank of approximately
300cc capacity is suggested.
This allows around 10 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.
11
Spinner
Since the FL-70 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.
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.
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 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 & Aerobatic
Trainer & Scale
12X7, 12.5X6, 13X6
12.5X6, 13X6-7
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.
12
TOOLS
HEX WRENCH
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 Wrenches
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, 13mm, 14mm, etc.
Needle Nose Pliers
13
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