O.S. engine MAX-75AX-BE 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.
1
2-6
7-8
9
10
20-21
22
28-31
15-17
SAFETY INSTRUCTIONS AND WARNINGS
ABOUT YOUR O.S. ENGINE
ENGINE CONSTRUCTION,
NOTES WHEN APPLYING AN ELECTTRIC STARTER
ABOUT THE ENGINE
BASIC ENGINE PARTS
BEFORE STARTING
INSTALLATION
INSTALLATION OF THE STANDARD ACCESSORIES
FUEL TANK LOCATION
MIXTURE CONTROLS
GLOWPLUG
CONTENTS
STARTING
RUNNING -IN, IDLING ADJUSTMENT CHART
MIXTURE CONTROL VALVE ADJUSTMENT
REALIGNMENT OF MIXTURE CONTROL VALVE,
SUBSEQUENT STARTINGPROCEDURE
TROUBLE SHOOTING WHEN THE
ENGINE FAILS TO START
CARE AND MAINTENANCE
ENGINE EXPLODED VIEW & PARTS LIST
CARBURETOR EXPLODED VIEW & PARTS LIST
O.S. GENUINE PARTS & ACCESSORIES
THREE VIEW DRAWING
32
33
34-35
36-37
38-39
40-41
11-14
18-19
23
42-43
44
24-27

2
Remember that your engine is not a "toy", but a highly efficient internal-
combustion 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.
SAFETY INSTRUCTIONS AND WARNINGS ABOUT YOUR O.S. ENGINE
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 NOTES
These cover events which
might involve serious (in
extreme circumstances, even
fatal) injury.
These cover the many other
possibilities, generally less obvious
sources of danger, but which, under
certain circumstances, may also
cause damage or injury.
3
WARNINGS
Never operate your engine in an en-
closed space. Model engines, like auto-
mobile engines, exhaust deadly carbon-
monoxide. 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.
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 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.
O.S. Bio - Ethanol fuel is not poisonous but
harmful. Do not allow it to be swallowed.
Always store it in a clearly marked
container and out of the reach of children.

4
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' recommenda-
tions, using appropriate screws and lock-
nuts.
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.
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.
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.
5
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.

6
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!
7
Piston
Cylinder Liner
Crankshaft
ENGINE CONSTRUCTION
Near TDC
Slight taper
When the engine is cold. When the engine is hot.
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.

8
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 from
getting into your eyes.
9
STANDARD ACCESSORIES
Glow Plug BE-3
(suppplied with the engine)
Needle Valve Extension Cable Set
E-4040 Silencer Assembly
Silencer Retaining Screw (M4x40 2pcs.)
ABOUT THE ENGINE
The MAX-75AX-BE has been developed and
designed to use O.S. Bio-Ethanol fuel only.
Therefore, some parts are different from
those of the MAX-75AX that use conventional
methanol based glow fuel. Also, special
attention is required in it’s handling.
This engine has been developed based on the
MAX-75AX, to use only O.S. Bio-Ethanol fuel.
It develops enough powerto fly general 61 size
sport models.
It is suggested to use propellers which develop
maximum r.p.m. of 8,500~9,500 so that you
may enjoy pleasant exhaust sound keeping it
low.
Glow plug, cylinder head, carburetor, drive hub
and silencer are different from those of the
MAX-75AX.

10
BASIC ENGINE PARTS
Cylinder head
Carburetor Type 61A-BE
Crankshaft
Propeller nut
Propeller washer
Drive Hub
Crankcase
Cover Plate
Glowplug
Beam Mount
Lock nut
11
Tools, accessories, etc. The following items
are necessary for operating the engine.
BEFORE STARTING
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, due to higher rpm or if a larger-
diameter/lower-pitched prop is used.
Propellers
13x9-10, 14x6-8, 15x6
Sport
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.
Reminder!
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.
Since the 75AX-BE 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.
Spinner
It is suggested to use propellers which develop
maximum r.p.m. of 8,500~9,500 so that you
may enjoy pleasant exhaust sound keeping it
low.

12
FUEL
O.S. Bio-Ethanol fuel is not poisonous but
harmful. Do not allow it to be swallowed.
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.
Reminder!
A fuel tank of approximately
160~180cc capacity is suggested.
This allows around 10-12 minutes flying time,
dependent upon, the size of propeller and on
the amount of full-throttle to part-throttle
operation throughout the flight.
Fuel Tank
GLOW PLUG
Use the O.S. Bio-Ethanol fuel (BE-1).
Other fuel cannot be used with this engine.
Do not use conventional methanol based glow
fuel, or the engine will not run properly and
strong knocking may occur, which may cause
the propeller to fly off.
The engine is supplied with a special
glow plug (BE-3) designed for this
engine. Use 1.2V~1.5V the same as
conventional glow plugs.
This glow plug has a different thread
size for both the dia. and pitch
purposely so that conventional glow
plugs may not be installed.
13
1,2V〜1.5V
S
GLOWPLUG IGNITER
Commercialy available handy
glowplug heater in which the
glowplug battery and battery leads are integrated.
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.
FUEL PUMP
Manual Electric
Electric Starter and
Starter Battery
Required when starting
the engine. 12-Volt lead-acid battery
Electric
Starter
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. Super Filter (Fuel Can Filter)
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, an
O.S. Non-Bubble Weight is available as
an optional extra.
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.
O.S. Non-Bubble Weight
Fuel Filter 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.

14
8mm
TOOLS
HEX Screwdriver
SCREWDRIVER
Necessary for engine installation.
1.5mm, 2.5mm
Necessary for carburetor adjustments.
Phillips Screwdriver
No.2, etc.
Socket Screwdriver
5mm, 5.5mm, 7mm
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.
End Wrenches
12mm, 14mm etc.
Needle Nose Pliers
15
It is suggested to use as heavy and rigid as possible engine mounting for highest performance and
safe running. Conventional wooden mounting beams should be of rigid hardwood and of at least
15mm or 5/8-in square section. Use at least 3mm steel screws, such as Allen type, with locknuts, for
bolting the engine to the bearers..
INSTALLATION
CORRECT
Top surfaces are in the same plane.
INCORRECT
Front view Side view
Re-align the surfaces
as necessary
Opposite beam
Top surfaces are not in the
same plane.
Engine does not rest firmly.
Top surfaces are not
in the same plane.
Make sure that the mounting beams are parallel and that their
top surfaces are in the same plane.

16
How to fasten the mounting screws.
Hardwood mounting beams
Radial motor mount (cast aluminum)
Tighten second nut
firmlydown onto first nut.
Tighten this nut first.
Steel washer
3mm steel nuts
3mm steel screw
Spring washer or
lock washer
15mm min.
15mm min. Hardwood such as
cherry or maple.
Spring washer
3.5mm
steel Allen screw
● Make sure that these mounting beams are
accurately aligned and firmly integrated with
the airframe, reinforcing the adjacent
structure to absorb vibration. Use 4mm or
larger steel screws, preferably Allen type
hexagon socket head cap screws, with
washers and locknuts, for bolting the engine
to the bearers.
O.S. Radial Motor Mount
A special O.S. radial motor mount (Code
No.71905200) is available, as an optional
extra, for use where firewall type mounting is
required.
17
THROTTLE LINKAGE
Before connecting the throttle to its servo,
make sure that the throttle arm and linkage
safely clear any adjacent part of the airframe
structure, etc., as the throttle is opened and
closed. Connect the linkage so that the throttle
is fully closed when the transmitter throttle
stick and its trim lever are at their lowest
settings and fully open when the throttle stick
is in its fully-open position. Carefully align the
appropriate holes in the throttle arm and servo
horn so that they move symmetrically and
smoothly through their full travel.

18
INSTALLING THE GLOWPLUG
Install washer on glowplug
and insert carefully into
cylinder-head, making sure
that it is not cross-threaded
before tightening firmly.
Glow plug
Washer
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. For this purpose a Needle
Valve Extension Cable Set is supplied with the
engine. If a longer extension is reguired, 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.
Needle Valve
Extension Cable Set
1.5mm Allen key.
Set Screw
INSTALLATION OF THE STANDARD ACCESSORIES
19
INSTALLING SILENCER E40400 Silencer
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.
Reminder!
The exhaust outlet of the silencer can be
rotated by 90 degrees the following manner:
Loosen the locknut and assembly screw.
Set the exhaust outlet at the required posi-
tion by rotating the rear part of the silencer.
Re-tighten the assembly screw, followed by
the locknut.
1)
2)
3)
Assembly screw
Locknut
Exhaust pressure nipple
Secure the silencer to the engine by means of
two retaining screws supplied after the engine
is securely mounted to a test bench or a
model.
It is recommended to seal the fitting faces of
engine exhaust and silencer with silicone
sealant.
Gasket
Baffle plate
Can be rotated
by 90 degrees.