O.S. engine MAX-91SZ-Hring 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.
1
CONTENTS
SAFETY INSTRUCTIONS AND
WARNINGS ABOUTYOUR O.S.ENGINE
NOTES ON INSTALLING,
COOLING-FAN AND CLUTCH
NOTES WHEN APPLYING AN ELECTRIC STARTER,
NOTES ON HEATING THE GLOW PLUG
INTRODUCTION, BEFORE STARTING
ENGINE PARTS NAME, INSTALLATION
OF THE STANDARD ACCESSORIES
INSTALLATION OF THE ENGINE,
FACTS ABOUT GLOWPLUGS
CARBURETOR CONTROLS
STARTING, RUNNING-IN ("Breaking-in")
2-5
6
13-15
18-19
22-26
27
29
39
ADJUSTMENT
ADJUSTMENT CHART
INSTALLATION OF THROTTLE SERVO
CARE AND MAINTENANCE
TROUBLE SHOOTING
ENGINE EXPLODED VIEW & PARTS LIST
CARBURETOR EXPLODED VIEW & PARTS LIST
O.S. GENUINE PARTS & ACCESSORIES
THREE VIEW DRAWING
MEMO
34-35
7-8
9-12
20-22
38
16-17
28
30-33
36-37
40

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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 ABOUTYOUR 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
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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.

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4
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.
•
•
5
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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.

6
Notes on installing cooling fan and clutch
Do not use a tool which
locks piston when
installing a cooling-fan
and clutch, or top of
the piston may be
damaged. Also, do not
insert a screw driver or
the similar into the
exhaust port.
It is recommended to use Crankshaft
Clamp 91 (Code No.71530510) available as
an optional tool.
It is made of durable engineering plastic
and locks the crankshaft without risk of
damage to any part of the engine.
Application is as follows:
Remove the crankcase rear cover plate from the
engine and rotate the crankshaft to the bottom
dead center (BDC) position.
Insert the crankshaft clamp so that its grooved
portion surrounds the crankpin and lower end of
the connecting rod and securely tighten the fan
or clutch onto the crankshaft.
Insert this groove onto
the connecting rod.
BDC position
Rotate the crankshaft so that the
connecting rod comes to this position.
7
NOTESWHEN APPLYING AN ELECTRIC STARTER
Because of this 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 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 from
getting into your eyes.

8
Note on heating the glow plug
The heatsink head on the engine is
treated with Alumite which does not
conduct current. Therefore, when
heating a glow plug, connect one
lead to the glow plug and the other
to the head of cover plate retaining
screw.
Example
9
This is a high performance engine
expressly designed for F3C
competition. The engine uses the
same mounting hole spacing as the
O.S. 61SX-H RING WC making them
interchangeable. However, higher gear
ratio is required for the MAX-91SZ-H
RING which generates maximum
power at lower rpm than the 61 size
engines. New design 60M-C carburetor
has three adjustable controls which
enables independent adjustment at
idling, hovering and high speed.
INTRODUCTION
Standard accessories
Glow Plug No.8
Woodruff Key
Needle Adjusting Screw (M2.6x5 2pcs.)
Instruction manual
Carburetor Complete 60M-C
Note:
As delivered, the carburetor is not
installed on the engine.
Carburetor Rubber Gasket
Carburetor Retainer Assembly
(M2.6x18)
Head Gasket
0.2mm 0.1mm

10
Items necessary for starting
Tools, accessories, etc.The following items are
necessary for operating the engine.
BEFORE STARTING
Glow Plug
O.S. No.8 is supplied with the engine.
Battery leads
Glowplug battery
The power source for heating the glowplug may be
either a large heavy-duty 1.5volt dry cell, Ni-cd battery
or glowplug Igniter.
1.5 volt dry cell
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.
Battery leads
glowplug Igniter
Make sure glowplug element
glows bright red inside room
or shadow.
Battery leads
In case of 1.5volt dry cell
12V Battery Starter
Electric starter and starter
battery
An electric starter is recom-
mended for starting.
Hexagon starting shaft
This shaft mounted on an
electric starting motor is driven
into the shaft cup to turn the
engine.
11
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.
Reminder!
Fuel
Model engine fuel is also highly flammable.
Keep it away from open flame, excessive
heat, sources of sparks, or anything else
whichmight ignite it.Do not smoke,or allow
anyone else to smoke, near to it.
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
Install a filter to 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)
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 Filter
Heatproof silicone tubing of approx.
5mm o.d. and 2.5mm i.d. is required
for the connection between the fuel
tank and engine.
Fuel Pump
Silicone Fuel Line

12
TOOLS
Screwdriver
Necessary for engine installation.
1.5mm, 2mm, 2.5mm, 3mm
Necessary for carburetor adjustments.
No.1, No.2, etc
Phillips Screwdriver
No.1, No.2, etc.
Socket Wrenches
5mm, 5.5mm, 7mm
Hex Wrench
8mm
Recommended for easy removal and replacement of
the angled and recessed glowplug, the O.S.Long
Socket Wrench incorporates a special grip.
EndWrenches
8mm, 13mm, 14mm, etc.
Needle Nose Pliers
Long SocketWrenchWith Plug Grip
13
ENGINE PARTS NAME
Heatsink Head
Carburetor
Typr 60M-C
Crankshaft
Propeller nut Crankcase
Glowplug
Beam Mount
Cover Plate
High Speed
Needle Valve
Fuel Inlet
Mixture Control Valve
Throttle Lever Idle Mixture Control Screw
Mixture Control
Valve Stopper
Thrust Washer
Carburetor Rubber Gasket
Medium Speed Needle Valve

14
JAPAN
INSTALLATION OFTHE CARBURETOR
1.
2.
Retainer screw Carburetor Rubber
Gasket 0.2mm gap
Carburetor Rubber
Gasket
INSTALLATION OF THE STANDARD ACCESSORIES
Retainer screw
Carburetor Retainer
Insertthe carburetor rubber
gasket on the carburetor
body securely.
Then, insert the carburetor
in the crankcase.
Note: In case it is hard to insert the carburetor in
the crankcase, apply oil on the carburetor body.
Do not force it, or damage the carburetor body
and/or crankcase.
Insert the carburetor retainer as illustrated.
Unscrew the retainer screw a little.
Rotate the retainer screw gently until it stops, then
tighten a further 90-120 degrees.
Do not over-tighten the screw as this will damage
the carburetor body.
3.
15
INSTALLING THE GLOWPLUG
Install washer on glowplug
and insert carefully into
Heatsink-head, making sure
that it is not cross-threaded
before tightening firmly.
Glow plug
Washer
The knurled heads of the two needle valves (High-
Speed and Medium Speed) are provided with
diagonal slots for use with a screwdriver.
Alternatively, formore positive location via an Allen
hexagonalkey, these headsalso have M2.6 internal
threads,intowhichM2.6x5mmAllencap-headscrew
may be installed. To avoid risk of damage to the fuel
passageswhentighteningthesescrews,removethe
needle valves from the carburetor and use 'Loctite'
thread-lock compound to secure the screw.
HEX KEY NEEDLE ADJUSTMENT
ABOUTTHE HEAD GASKET
ABOUTTHE WOODRUFF KEY
Needle Adjusting screw
The engine is installed with a 0.2mm thick head
gasket at the factory. If necessary according to the
fuel used, atmospheric conditions and glow plug
used, adjust the thickness with the extra 0.2mm and
0.1mm gasket supplied with the engine.
Use the woodruff key supplied with the engine if the
fan pulley of the model has a groove to accept it.

16
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 4-40
steel Allen type. It is also advisable to use lock
washers or LOCTITE to prevent nuts from loosening.
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.
17
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.
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.

18
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
60M'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.
Three adjustable mixture controls are incorporated in the
Type 60M-C. They are as follows.
A
B
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
Idle MIxture Control Screw
High Speed Needle Valve
(Main Needle)
Medium Speed
Needle Valve
Needle
Adjusting screw
As the idle mixture control screw is installed with
LOCTITE, it may initialy feel stiff, and it is suggested
to use a littli oversized screwdriver. The screw can be
turned only 90 degrees either way. Do not force to turn
further, or it may break or cause trouble.
NOTE
90 degrees
90 degrees
19
BASIC POSITION OF MIXTURE CONTROL SCREW
(Mixture Control Valve)
Thick
Mixture Control Valve
MIxture Control Screw
Lean
As delivered, the Mixture Control Screw is
positioned at approximately the center as shown in
the sketch.
Mixture gets lean when the Mixture Control Screw
is turned right, while mixture gets rich when the
Mixture Control Screw is turned left.
With a model helicopter, adjustments vary with
combined various factors such as climatic
conditions, fuel, muffler, main rotor, weight of the
model, gear ratio, etc. Therefore, Mixture Control
Screw position varies with each model and set- up,
and it is normal if the Mixture Control Screw
position is off the center.
89 degrees
When the triangle mark on the carburetor rotor meets
the far right mark, the throttle is fully closed. When
the triangle mark meets the top mark, the throttle is
fully open. The range is 89 degrees. You may use
the other three marks as the reference marking of
throttle opening to your preference when hovering.
WARNING!
Never try to check the triangle mark position
while the engine is running and rotor is
rotating, or you may be hit by rotating rotor which
results in serious injury. Stop the engine and
rotor before checking the triangle mark position.
Carburetor Rotor
Carburetor Body
Fully closed
position
Fully opened position
As shown in the sketch, the carburetor has
graduation marks.
GRADUATIONS ON THE CARBURETOR BODY

20
STARTING
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:
at basic position when the engine leaves the
factory.
exactly two turn open from the fully closed position.
Medium Speed needle-valve:
Close
4.
5.
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.
3. Preparation of the starter
Install the starting shaft to the
starter securely.
Improper installation will allow the
shaft to swing creating a
dangerous situation.
21
6. Priming
Without energizing the glowplug, open the throttle
a little from the idling position. Turn the engine
over 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 fuel line to stop the
fuel supply. If it still does not stop, pull off the fuel line
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
cannotrotatewhentheengineisStarted.Also,steady
the model with a foot on the landing gear skid.
7.
8.
9.
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
rotor.

22
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
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.
RUNNING-IN ("Breaking-in")
ー
ADJUSTMENT
Please observe the following before beginning to
make any adjustment.
High-Speed Needle Valve. Turn this approximately
30 degrees (3 to 4 click) at a time, when making
initial adjustments; then in steps of approximately
15 degrees (1 to 2 clicks) when making final
adjustments.
Medium-Speed Needle Valve. Turn approximately
30 degrees (3 to 4 click) at a time.
Idle Mixture Control Screw. Turn approximately 5
degrees at a time. It turns approximately 90
degrees both side from the center. Turn left to
enrich the idle mixture and turn right to lean the idle
mixture.
23
The general course of adjustment procedure is
shown in the ADJUSTING CHART and is correct
for a fuel containing 20% lubricant and 15-30%
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.
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.
This carburetor is not equipped with a throttle
stop screw. Instead, idling speed is adjusted
by means of the throttle trim lever on the
transmitter.
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 idle 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 5 degrees. 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. 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 5 degrees to
enrich the mixture.
ADJUSTMENT PROCEDURE
1.

24
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.
2. 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 will have
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.
When satisfactory hovering flight has been achieved,
land the modeI again and re-check the engine's idle
qualities.
25
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
idle performance, fine tuning 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 30 degrees, or 3-4 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.

26
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
carburetor 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 wrench
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 previously 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.

27
ADJUSTING CHART
High Speed Needle Valve - 2 turns opened from fully closed position.
Medium Speed Needle Valve - 2 turns opened from fully closed position.
Start the engine
Warm up the engine
Observe the mixture condition while "floating" the model
Turn the Idle Mixture
Control Screw counter-
clockwise 5 degrees Idling OK
Turn the Idle Mixture
Control Screw
clockwise 5 degrees
Lean mixture Rich mixture
Observe the hovering mixture condition
Open the High Speed
Needle Valve
(Turn counter-clockwise)
Hovering OK
Lean mixture Rich mixture
Close the High Speed
Needle Valve
(Turn clockwise)
Land the model
Idle for approx: 10 seconds, then reopen throttle to
observe transition ("Float" the model)
Idling OK
Lean mixture Rich mixture
High Speed Flight
Lean mixture Rich mixture
High Speed Flight OK
Fine tuning of hovering mixture
Open the Medium
Speed Needle Valve Hovering OK
Adjustment completed
Open the High Speed
Needle Valve
(Turn counter-clockwise)
Close the High Speed
Needle Valve
(Turn clockwise)
Fine tuning of idling mixture
Lean mixture Rich mixture
Idling OK
Lean mixture Rich mixture
Close the Medium
Speed Needle Valve
Turn the Idle Mixture
Control Screw
clockwise 5 degrees
Turn the Idle Mixture
Control Screw
clockwise 5 degrees
Turn the Idle Mixture
Control Screw counter-
clockwise 5 degrees
Turn the Idle Mixture
Control Screw counter-
clockwise 5 degrees

28
INSTALLATION OF THROTTLE SERVO
Servo output arm
Throttle arm
After the engine is installed in the helicopter, please
observe the following recommendations when linking
the throttle servo to the carburetor.
Locatetheservoso thatitsoutputarmand the
throttle pushrod are, as close as possible,
directry in line with carburetor's throttle arm,
as shown.
Throttle control rod A and B should be equal length.
Set the linkage so that the servo output arm and
throttle arm are parallel when the throttle stick on the
transmitter is at middle position. If differential throttle
movement is required, make necessary adjustment
at the transmitter.
27mm
29
CARE AND MAINTENANCE
The minute particles of foreign matter, that are
present in any fuel may, by accumulating and
partially obstructing fuel flow, cause engine
performance to become erratic and unreliable.
O.S. 'Super-Filters' (large and small)are available,
as optional extras, to deal with this problem.
One of these filters, installed on the outlet tube
inside your refueling container, will prevent the
entry of foreign material into the fuel tank. It is also
recommended that a good in-line filter be installed
between the tank and carburetor.
1.
Finally,injectsomeafter-runoilintotheengine.Rotate
the engine a few times by hand, to make sure that it
is free, and then with an electric starter for 4 to 5
seconds to distribute the oil to all the working parts.
These procedures will reduce the risk of starting
difficulties and of internal corrosion after a period of
storage.
Donot inject after-run oil into the carburetor as this may
cause the O-rings inside the carburettor to deteriorate.
Note:
2.
3.
4.
Do not forget to clean the filters regularly to remove
dirt and lint that accumulate on the filter screens.
Also, clean the carburetor itself occasionally.
At the end of each operating session, drain out any
fuel that may remain in the fuel tank. Next, energize
the glowplug and try ot restart the engine to burn off
any fuel that may remain inside the engine.
Repeat this procedure until the engine fails to fire.
Removetheglowplugandejectanyremainingfuel/oil
residue by rotating the engine with an electric starter
for 4 to 5 seconds while the engine is still warm.
When storing a helicopter installed with an engine or
placingitattheairtieldstationary,placearestunderone
side of the skid, which make a next engine start easier
due to draining the surplus oil.
Skid
Rest

30
TROUBLE SHOOTING Symptom
Cause Corrective action
Engine fails to fire.
Fuel tank is empty.
Fuel not reaching the engine. Fill the tank with fuel and repeat
Priming procedure.
Glowplug element is burnt out.
Glowplug battery discharged Replace glowplug. Recharge or replace the battery.
Clogged fuel filter
Silencer inside is dirty. Clean or replace fuel filter.
Clean inside silencer.
Over priming Remove glowplug and pump excess fuel.
Fuel tubing is disconnected. Connect fuel tubing securely.
Fuel tubing is kinked, split or has a hole.
Check the tubing carefully and replace if necessary.
Incorrect carburetor settings Return the needle valve
and mixture control valve to basic position.
Incorrect servo linkage Re-linkage after setting servo at neutral.
Reverse rotating direction of electric starter. Mare sure it rotates counter clockwise seen
from crankshaft side.
31
Symptom
Cause Corrective action
Engine fires intermittently but does not run.
Insufficient fuel in the tank. Fill the tank with fuel.
Deteriorated glowplug Replace glowplug.
Clogged fuel filter
Silencer inside is dirty. Clean or replace fuel filter.
Clean inside silencer.
Engine overheated Wait until engine is cooled.
Disconnecting plug battery too soon. Do not disconnect plug battery and wait until
r.p.m. become stable.
Air bubbles in fuel Fit O rings to the tank screws to
prevent bubbles.

32
Symptom
Cause Corrective action
Symptom
Cause Corrective action
Unstable idle
Unsuitable glowplug Use suggested glowplug in the instructions.
Unsuitable fuel Do not use extremely high nitro or low oil fuel.
Silencer is disconnected or has play Install silencer securely.
Not reaching expected peak r.p.m.
Insufficient warming up or running-in. Set the needle only after warming up.
Complete running-in.
Silencer or manifold is not securely connected
or disconnected. Check the connections and secure them.
Fuel tubing from tank to is split or broken. Replace the tubing.
33
Symptom
Cause Corrective action
Symptom
Cause Corrective action
Poor response
Deteriorated glowplug Replace glowplug.
Incorrect carburetor settings Readjust low r.p.m.range with metering
needle and mixture control valve.
Poor r.p.m. drop
Too much throttle opening at idle. Lower the throttle trim to adequate position
to lower idling r.p.m.
Incorrect carburetor fitting Fit carburetor securely.
Inaccurate linkage Recheck the throttle opening against
the pith angle.
Needle-valve closed too far. Open needle-valve slightly

34
ENGINE EXPLODEDVIEW
Type of screw C…Cap Screw M…Oval Fillister-Head Screw
F…Flat Head Screw N…Round Head Screw S…Set Screw
＊
C.M3x15
C.M3x12
1
2
3
45
6
7
8
910
11 12
13
14
15
16
17
C.M2.6x18
35
The specifications are subject to alteration for improvement without notice.
ENGINE PARTS LIST
Heatsink Head
Cylinder Liner
Piston Ring
Piston
Piston Pin
Piston Pin Retainer (2pcs.)
Connecting Rod
Carburetor Complete 60M-C
Propeller Nut
Thrust Washer
Crankshaft Ball Bearing (Front)
Carburetor Retainer Assembly
Crankcase
Crankshaft Ball Bearing (Rear)
Crankshaft
Gasket Set
Cover Plate
Glow Plug No.8
Woodruff Key
Needle Adjusting Screw
Head Gasket (0.1mm, 0.2mm)
No. Description
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Code No.
29064000
29063100
29503400
29063200
27006000
27917000
29505010
29183000
45010002
46120000
26731002
23981700
29061000
27930000
29062000
29061400
29067000
71608001
27708200
41621100

36
CARBURETOR EXPLODED VIEW
Type of screw
C...Cap Screw M...Oval Fillister-Head Screw
F...Flat Head Screw N...Round Head Screw S...Set Screw
C.M3x8
1
1-1
2
3
3-1
3-2
3-3
4
5
6
7
8
8-1
8-2
8-3
8-4 8-5
8-6
9
9-1
9-2
9-3
9-4
10
37
The specifications are subject to alteration for improvement without notice.
CARBURETOR PARTS LIST
No. Description
Code No.
1
1-1
2
3
3-1
3-2
3-3
4
5
6
7
8
8-1
8-2
8-3
8-4
8-5
8-6 Ratchet Spring
Needle
Needle Valve Assembly
Fuel Inlet
Rotor Guide Screw
"O"Ring (L) (2pcs.)
Carburetor Body
Mixture Control Valve Assembly
Carburetor Rotor
Throttle Lever Retaining Screw (2pcs.)
Throttle Lever Assembly
Mixture Control Screw
Mixture Control Valve Stopper
Needle Valve Holder Assembly
"O"Ring (L) (2pcs.)
"O"Ring (S) (2pcs.)
"O"Ring (2pcs.)
Needle Valve Holder
9
9-1
9-2
9-3
9-4
10 Carburetor Rubber Gasket
Needle
Needle Valve Assembly
"O"Ring (2pcs.)
Needle Valve Holder Assembly
Ratchet Spring
Needle Adjusting Screw (5pcs.)
No. Description
Code No.
27381410
22826131
29183200
29181610
27881810
27881800
27881820
45581820
29183100
27881330
27681340
27081900
27981910
24981837
46181940
46181941
26711305
46181950
27981900
27981910
24981837
27381940
26711305
29015019
41621100