O.S. engine MAX-61SX-H RING WC Series Setup guide

It is of vital importance, before attempting to
operate your engine, to read the general
'SAFETY INSTRUCTIONS AND WARNINGS'
section on pages 2-5 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 model, radio control equipment, etc.,
are accessible for checking at the same time.
•
•

CONTENTS
SAFETY INSTRUCTIONSAND WARNINGS
ABOUT YOUR O.S. ENGINE
INTRODUCTION
BASIC ENGINE PARTS,
INSTALLATION OF THE CARBURETOR
INSTALLATION OF THE ENGINE
BEFORE STARTING
FACTS ABOUT GLOW PLUGS
FUEL,CARBURETOR CONTROLS
STARTING
RUNNING-IN,ADJUSTMENT
SUBSEQUENT READJUSTMENTS
CARBURETTOR CLEANLINESS
ADJUSTING CHART
INSTALLATION OF THROTTLE SERVO
CARE AND MAINTENANCE
ENGINE EXPLODED VIEW &
PARTS LIST
CARBURETOR EXPLODED
VIEW & PARTS LIST
THREE VIEW DRAWING
O.S. GENUINE PARTS &ACCESSORIES
2 ~ 5
6
7
8
9
~ 10
11
12
~ 13
19
19
21
22
~ 29
13
~ 15
20
34
15 ~ 18
30 ~ 31
32
~ 33
1

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.
2

WARNINGS
••
•
•
•
Never touch, or allow any
object to come into contact
with, the rotating parts.
Model engine fuel is poison-
ous. 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,oranythingelsewhich
might ignite it. Do not smoke
orallowanyoneelsetosmoke,
near to it.
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 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.
3

NOTES
•
•
•
•
•
These engine were designed for model
helicopters. Do not attempt to use it for any
other purpose.
Mount the engine in your model securely, fol-
lowing the manufacturers' recommendations,
using appropriate screws and locknuts.
Install an effective silencer (muffler). Frequent
close exposure to a noisy exhaust (especially
in the case of the more powerful high-speed
engines) may eventually impair your hearing
and such noise is also likely to cause
annoyance to others over a wide area.
Check the linkage to the throttle arm before
each flight.
Avoid sudden high r.p.m. immediately after the
engine is started, as the clutch will engage and
you may be struck by the rotor.
•
•
After starting the engine, carry out any needle-
valve readjustments after stopping the rotor by
closing the throttle to the lowest r.p.m..
Stop the engine before attempting to make
other adjustments to the carburetor.
Use an electric starter. The wearing of safety
glasses is also strongly recommended.
Press the rotor head down securely.
Take care that the glow plug clip or battery
leads do not come into contact with rotating
parts.
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.
•
•
4

NOTES
•
•
•
Take care that loose clothing (ties, shirt sleeves,
scarves etc.) do not come into contact with the
rotor. Do not carry loose objects (such as pen-
cils, screwdrivers, etc.) in a shirt pocket from
where they could fall through the rotor disc.
For their safety, keep all onlookers (especially
small children) well back (at least 20 feet or 6
metres) 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.
Hold the rotor securely and keep well clear of
spectators.
Warning! lmmediately after a glowplug-ignition
engine has been run and is still warm,
conditions sometimes exist whereby it is just
possible for the engine to restart when turned
over WITHOUT the glowplug battery being
reconnected. Remember this if you wish to
avoid the risk of accidents.
5

Because of initial tightness, a
standard electric starter may have
difficulty in rotating the engine when
cold, before it has been adequately
run-in. In this case, use a high-torque
type starter.
DO NOT, however, confuse tightness
with the symptoms of hydraulic lock
caused by an excess of fuel within the
cylinder - often the result of over-
priming.
Attempting to force the engine to turn
over in this condition may cause
internal damage. Instead, remove the
glowplug, invert the engine and eject
surplus fuel from the combustion-
chamber.
Note:
The MAX-61SX-H RING "WC" is an up-rated
version of the MAX-61SX-H RING helicopter
engine. It is aimed at FAI World
Championship(hence the suffix 'WC') Class
F3C competition. Performance has been
increased and the Type 60B carburetor has
been modified for easier adjustment. High
quality and high performance have been
confirmed in exhaustive flight testing and
in F3C contest results. The 61SX-H has a
traditional sideexhaust layout, whereas the
61RX-H features a rear exhaust for users
who prefer such a configuration. In all other
respects, the two models are of identical
design.
INTRODUCTION
6

BASIC ENGINE PARTS
Heatsink Head
Carburettor
Typr 60B
Crankshaft
Propeller nut
Crankcase
Drive Hub
Glowplug
Beam Mount
INSTALLING THE GLOWPLUG
Install the washer on the
glowplug and screw
carefully into cylinder-
head, making sure that it
is not cross-threaded
before tightening firmly. Glow plug
Washer
Cover Plate As delivered, the engine has its carburetor lightly
fitted into its intake boss. Secure it as follows.
INSTALLATION OF THE CARBURETOR
Retainer
screw
Carburetor Rubber
Gasket
0.2mm gap
Loosen the retainer screw, rotate the carburetor to
its correct position and press it well down into the
intake boss, compressing the rubber gasket as
shown in the sketch, before re-tightening screw.
Rotate the retainer screw gently until it stops, then
tighten a further 120-180 degrees. Do not over-
tighten the screw as this will damage the thermo-
insulator.
1.
2.
Positioning Mark
MAX-61SX-HRING"WC"
7

Front view
CORRECT
Side view
Top surfaces are in the same plane.
Re-align the surfaces as necessary
INCORRECT
Top surfaces are not
in the same plane. Top surfaces are not in the
same plane.
Engine does not rest firmly.
Make sure that only the under-surfaces
of the engine’s mounting lugs are in
contact with the engine mount.
If the crankcase body touches the
mount, chamfer the edges of the mount.
INSTALLATION OF THE ENGINE
The under-surfaces of all O.S. engine beam
mounting lugs are precision machined flat and
exactyly parallel to the engine's horizontal axis. It is
essential that the engine mounts in the model are
also accurately made and aligned. If they are not,
they will cause stress and distortion within the engine
itself, probably resulting in loss of performance and
internal damage.
The recommended screws for securing the engine to
the engine mounts in the model are 4mm or 6-32 NC
steel Allen type. It is also advisable to use lock
washers or LOCTITE to prevent nuts from loosening.
8

3 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 .
1.5 volt heavy-duty
dry battery or 2 volt rechargeable lead-acid cell (at least 5Ah)
If a 2-volt cell is employed,
use a resistance wire, as
shown, to reduce applied
voltage, otherwise element
will overheat and burn out.
Resistance coil
(nichrome wire)
Adjust applied voltage by changing the position of clip on
resistance coil until glowplug element is glowing bright red.
Battery leads
Raise
voltage to
increase
brightness.
Lower voltage to
reduce brightness.
Warning (Very hot)
Never touch the
nichrome wire
while the battery
is connected.
4 Plug wrench
Used for tightening glowplug. The
O.S. long plug wrench is available
as an optional accessory.
5 Battery leads
These are used to conduct current
from the battery to the glowplug.
Basically, two leads, with clips, are
required, but, for greater conve-
nience, twin leads with special
glowplug connectors, as shown on
the right, are commercially available.
For tightening
glowplug
Battery leads
2 Glowplug
O.S. No.8 glowplug is installed in the engine.
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.
9

Fuel Can Filter 12V Battery Starter
7 Fuel container filter
Install a filter on the outlet tube of
your refuelling container to prevent
entry of foreign matter into the fuel
tank
8 Silicone tubing
This is required for the
connection between the fuel
tank and engine.
9 Hexagon starting shaft
This shaft mounted on an
electric starting motor is driven
into the main body of a
helicopter to turn the engine.
Silicone tube
10 Electric starter and starter
battery
An electric starter is recom-
mended for starting.
6 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
fuelpumpsmay beusedtotransfer
fuel directly from your fuel
container to the fuel tank.
Fuel bulb
Manual
Electric
Fuel pumps
10

Install a plug suitable for the engine.
Use fuel containing a moderate percentage of
nitromethane.
Do not run the engine too lean and do not leave the
battery connected while adjusting the needle.
However, plug life can be extended and engine
performance maintained by careful use, i.e.:
Apart from when actually burned out, a plug may
need to be replaced because it no longer delivers its
best performance, such as when:
When to replace the glowplug
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.
•
•
•
•
•
•
•
•
FACTS ABOUT GLOWPLUGS
The role of the glowplug
Glowplug life
Particularly in the case of very high performance
engines,
glowplugs must be regarded as expendable
items.
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.
Since the compatibility of glowplug and fuel may have
a marked effect on performance and reliability, it may
be worthwhile to choose the R/C type plug found
most suitable after tests. Recommended O.S. plugs
are No.8 and A5. Carefully install plug finger-tight,
before final tightening with the correct size plug
wrench.
11

CARBURETOR CONTROLS
With a fixed-wing model, power failure is rarely a
serious threat to the safety of the aircraft since it can
usually glide down to a safe landing. In a helicopter,
on the other hand, it is vitally imporant that the engine
keeps running and that there is a quick and reliable
response to the throttle in order to ensure safe ascent
and descent of the model.
The High-Speed (Main) Needle Valve
When set to produce maximum power at full
throttle, this establishes the basic fuel/air mixture
strength. This is then maintained by the carburetor's
automatic mixture control system to cover the
engine's requirements at reduced throttle settings.
The Idle Mixture Control Screw
This provides the means of manually adjusting the
60B's mixture control valve. By setting the Mixture
Control Screw for the best idling performance, the
mixture control valve automatically ensures that fuel is
accurately metered to maintain the correct mixture
strength as the throttle is opened.
FUEL
Select, by practical tests, the most suitable fuel from
among the best quality fuels available in your country
for helicopter use. For the best throttle response, a
fuel containing 10% to 30% nitromethane is
preferable. Lubricants may be either castor-oil or a
suitable synthetic oil (or . a blend of both) provided
that they are always of top quality. For consistent
performance and long engine life, it is essential to use
fuel containing AT LEAST 18% lubricant by volume.
Some fuels containing coloring additives tend to
deterriorate and may adversely affect running
qualities. If in doubt compare to a fuel known to be
good.
Modelenginefuelispoisonous.Donotallow
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
whichmightigniteit.Do not smoke, or allow
anyone else to smoke, near to it.
Reminder!
Three adjustable mixture controls are fitted to the Tyoe
60B. They are as follows.
A
B
12

The Medium Speed Needle Valve
This is an extra control that can be brought into
play, if necessary, after adjusting A and B above. It
provides the means of fine-tuning mixture strength
over that all-important part of a helicopter's throttle
range where the model is flying in, or near, the
hovering mode.
C
STARTING
Close
Open
Be sure to use a muffler pressurized fuel feed. Use
the same fuel as you intend to employ for actual
operation of your model.
1.
2.
Opening and closing of the Needle-Valve
Turn the needle clockwise to
close the needle-valve, and turn
the needle counter-clockwise to
open the needle-valve as shown
in the sketch.
High Speed needle-valve:
exactly two turns open from the fully closed
position.(Note: If a different muffler is used, this
setting may require readjustment)
Idle Mixture Control Screw:
exactly two turns open from the fully closed
position.
exactly one turns open from the fully closed
position.
Medium Speed needle-valve:
Idle MIxture Control Screw
High Speed Needle Valve
(Main Needle)
Medium Speed Needle Valve
HEX KEY NEEDLE ADJUSTMENT
Theknurledheadsofthetwoneedlevalves(High-Speed
andMediumSpeed)areprovidedwithdiagonalslots for
use with a screwdriver. Alternatively, formore positive
location via an Allen hexagonal key, these heads also
haveM2.6internalthreads,intowhichM2.6x5mmAllen
cap-head screw may be fitted. To avoid risk of damage
to the fuel passages when tightening these screws,
remove the needle valves from the carburetor and use
'Loctite' thread-lock compound to secure the screw.
13

4.
5.
6.
Checking the rotating direction of the starter
Make sure that the starter rotates
to the direction shown in the
sketch. If the direction is reverse,
reverse the leads on battery.
Inserting the starter shaft
Insert the starting shaft into the
shaft cup securely.
Priming
Without heating the glowplug, open
the throttle a little from the idling
position. Turn the engine using the
starter until the fuel is seen to reach
carburetor.
In case the engine does not stop.
Hold the rotor head, and pinch the silicone tube to
stop the fuel supply. If it still does not stop, pull off the
fuel tubing from the carburetor.
It is necessary to readjust the throttle linkage so that
the carburetor rotor is fully closed when the throttle
stick and throttle trim on the transmitter are fully
pulled Down.
Stopping the engine
Fully pull down the throttle trim on the transmitter.
Starting
Connect the battery to the glowplug and start the
engine by applying the starter. When started, switch
off the starter and withdraw the starting shaft after
making sure the rotation of the starter shaft stops.
Preparation of starting
Make sure that the transmitter
throttle stick is at the fully closed
positionandthethrottletrimatcenter
position, and make sure that idle-up
switch on the transmitter is off. Hold
the rotor head by hand so that rotor
cannot rotate when the engine is Started. Also,
steadythemodel with afoot on the landinggearskid.
7.
8.
9.
3. Preparation of the starter
Install the starting shaft to the
starter securely. Poor installation
swings the starting shaft, which is
dangerous.
14

-
-
short and simple running-in procedure is required and
can be carried out with the engine installed in the
model. For the first few flights with a new engine i.e.
while the engine is being run-in set the needle-valve
for a slightly rich mixture not excessively rich as this
may result in poor throttle response and cause the
engine to stope. About one half turn open from the
nomal setting will usually suffice.
-
ADJUSTMENT
NOTE:
If the throttle response is poor or the engine
stops due to a temporarily over-rich mixture im-
mediately after the engine is started, pinch the
fuel line for one or two seconds until the engine
r.p.m. increase and the engine runs steadily.
Reminder!
Never touch, or allow any object to
come into contact with, the rotating ro-
tor.
All internal-combustion engines benefit, to some
degree, from extra care when they are run for the first
few times known as running-in or breaking-in.
This is allows the working parts to mate together
under load at operating temperature.
However, because O.S. engines are made with the
aid of the finest modern precision machinely and from
the best and most suitable materrials, only a very
RUNNING-IN ("Breaking-in")
-
Please observe the following before beginning to
make any adjustment.
•High-Speed Needle Valve. Turn this approximately
30˚ (3 to 4 click) at a time, when making initial
adjustments; then in steps of approximately 15˚ (1
to 2 clicks) when making final adjustments.
•Medium-Speed Needle Valve. Turn approximately
45˚ (4 to 5 click) at a time.
15

As a safety measure, first check the transmitter
controls, including the throttle stick and trim lever
positions, and hold the main rotor securely before
starting the engine.
The general course of adjustments procedure is
shown in the ADJUSTING CHART and is correct for
a fuel containing 20% lubricant and 10-30%
nitromethane.
Bear in mind that fuels containing relatively large
percentages of power-boosting nitromethane operate
at richer mixture settings than are needed for mild
fuels and will, therefore, require the High-Speed
Needle Valve to be readjusted accordingly. The type
and percentage of lubricant used is also a factor
here, as noted later in these instructions.
This carburetor is not fitted with a throttle stop
screw. Instead, idling speed is adjusted by
means of the throttle trim lever on the trans-
mitter.
•Idle Mixture Control Screw. A special technique is
required here. If intending to make an adjustment
(e.g. 90˚ in the same direction, before returning it to
the new setting. If this procedure is not followed,
movement of the throttle rotor may become stiff,
resulting in undue loading of the throttle servo.
Existing Position
Richer Leaner
Desired Position
Warm the engine by allowing it to idle for about 30
seconds. If the engine stops, advance the throttle
trim lever slightly to increase the idling rpm. Then
open the throttle sufficiently to 'float' the model
above the ground.
lf, at this time, the engine is slow to pick up and
produces an excess of exhaust smoke, the
mixture is too rich. Correct this condition by
turning the Mixture Control Screw clockwise. lf the
mixture is extremely rich, engine rpm will become
unstable: opening the throttle will produce a great
deal of smoke and rpm may drop suddenly or the
engine may stop. This condition may also be
initiated by an excessively prolonged warming-up
period.
ADJUSTMENT PROCEDURE
1.
16

Having provisionally set the idle mixture, the next
step is to adjust the mixture for hovering flight.
Hover the model and actuate the throttle to
observe response over the medium speed range.
lf the engine smokes excessiveIy and throttle
response is poor, the mixture is too rich ; in which
case, land the model and turn the High-Speed
Needle Valve clockwise. Do not close the High-
Speed NeedIe Valve more than the recommended
initial adjustment (3 to 4 clicks) at a time, keeping
it a little on the rich side at this stage. DO NOT
touch the Medium Speed Needle Valve.
lf, on the other hand, hovering is not stable and
response to the throttIe is over-sensitive, or if the
engine tends to overheat, this indicates that the
mixture is too lean and should be corrected by
turning the High-Speed Needle Valve counter-
clockwise.
lf, on the other hand, the mixture is too Iean, this
wiIl be indicated by a marked lack of exhaust
smoke and a tendency for the engine to cut out
when the throttle is opened. ln this case, turn the
Mixture Control Screw counter-clockwise to enrich
the mixture.
2.
When satisfactory hovering flight has been
achieved, land the modeI again and re-check the
engine's idlling qualities.
After about 10 seconds of idling, open the throttle
to 'float' the model. lf the transition is smooth, the
idle mixture is O.K. If the symptoms of either rich
or Iean running are
observed, readjust the Idle
Mixture Control Screw accordingly.
NOTE: With this carburetor, neither the Idle Mixture
Control Screw adjustment, nor the Medium Speed
Needle Valve adjustment has any effect on mixture
strength when the throttle is fully (or almost fully)
open.
Throttle Opening
Fully Closed 1/3 2/3 Fully Open
Fuel Flow
Maximum Minimum
Adjustment range of Idle Mixture
Control Screw
Adjustment range of Medium
Speed Needle Valve
Needle Valve too
far open
Needle Valve too
far closed
High Speed Needle
Valve Setting varies
according to the curve.
17

Now re-check hovering performance It may be
found that (with the High-Speed Needle Valve
now set for optimum full-throttle performance)
hovering will reveal symptoms of slightly lean
running at medium speeds. DO NOT touch the
High-Speed Needle Valve.
Now adjust the High-Speed Needle Valve to
achieve the best performance when the model is
flying at full throttle. lf, at full throttle, acceleration
is poor, the exhaust unduly smoky and the model
fails to reach expected straight line speed, the
mixture is too rich and the High-Speed Needle
Valve setting will need to be reduced.
lf, however, after smoothly acceIerating to
satisfactory high-speed straight and level flight,
power is lost when the model is puIled up into a
climb, the mixture is too lean. ln this case, land the
model immediately and readjust thw High-Speed
Needle Valve to a richer setting.
3.
4. Having now found the optimum setting for the
High-Speed Needle Valve, re-check the engine's
idling performance, finetuning the Idle Mixture
Control Screw, if necessary, to perfect the idle.
5.
It is at this point that the Medium Speed Needle
Valve, previously kept one turn open, may be
brought into operation. Open the Medium Speed
Needle Valve 45˚, or 4-5 clicks, then fine tune until
the optimum hovering performance is obtained. If
on the other hand, hovering reveals rich running,
close the Medium Speed Needle Valve gradually
until the optimum hovering performance is
obtained.
NOTE: It is NOT necessary to open the Medium
Speed Needle Valve if symptoms of lean running at
hovering speeds remain unconfirmed.
18

CARBURETOR CLEANLINESS
The correct functioning of the carburetor depends on
its small fuel orifices remaining clear.
The minute particles of foreign matter that are present
in any fuel can easily partially obstruct these orifices
and upset mixture strength so that engine
performance becomes erratic and unreliable.
It is recommended that fuel is passed through a filter
when the tank is filled and that a good in-line filter is
installed between the fuel tank and carburettor and,
furthermore, that this filter is frequently cleaned to
remove dirt and lint that accumulates on the filter
screen.
Finally, occasionally remove the needle-valve holder
from the carburetor as shown in Photo and extract
any remaining foreign matter that may have lodged in
the location shown in Photo, right.
Remove this with
an 8mm spanner Dirt and fbrous matter
mostly accumulate here
SUBSEQUENT READJUSTMENTS
Once the engine has been run-in and the carburetor
controls properly set up, it should be unnecessary to
alter the mixture settings, except to make minor
changes to the Main (High-Speed) Needle Valve
occasionally, to take account of differences in climatic
condisitions.
However, as oreviously mentioned, the use of a
different fuel, particularly one containing more, or
less, nitromethane and / or a different type or
proportion of lubricating oil, is likely to call for some
modification to the High-Speed Needle-Valve
adjustment.
As a safety measure, it is advisable to increase the
High-Speed Needle Valve setting by an extra half-turn
counter-clockwise, prior to establishing the new
setting. The same applies if the silencer type is
changed. A different silencer may alter the exhaust
pressure applied to the fuel feed and call for a revised
Needle-Valve setting.
The use of a different glowplug, or changes to the
main rotor and its pitch angles may also require
compensating carburetor readjustments.
19