O.S. engine MAX-12TG-P User manual

It is of vital importance, before attempting to operate
your engine, to read the general 'SAFETY
INSTRUCTIONS AND WARNINGS' section on
pages 2-5 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 vehicle, radio control equipment, etc., are
accessible for checking at the same time.
JAPAN
1
2-5
6-7
8
9
10-11
12
13-15
16
17
18-19
20-26
27-30
31-34
35-37
38-45
46-49
50-52
53-56
CONTENTS
SAFETY INSTRUCTIONS AND
WARNINGS ABOUT YOUR O.S. ENGINE
ENGINE CONSTRUCTION, NOTES WHEN
APPLYING AN ELECTRIC STARTER
INSTRUCTIONS
BASIC ENGINE PARTS
TOOLS, ACCESSORIES, etc.
STANDARD ACCESSORIES
CARBURETOR CONTROLS,
INSTALLATION OF THE CARBURETOR
NOTES CONCERNING THE RECOIL STARTER
GLOWPLUG
ENGINE INSTALLATION
STARTING THE ENGINE &
RUNNING-IN ('Breaking-in)
FINAL ADJUSTMENT
TROUBLE SHOOTING
CARE AND MAINTENANCE
EXPLODED ENGINES VIEWS &
PARTS LIST
CARBURETOR EXPLODED VIEW &
PARTS LIST
O.S. GENUINE PARTS & ACCESSORIES
THREE VIEW DRAWING

2
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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 applies basically to ALL MODEL ENGINES and 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
Model engine fuel is poi-
sonous. Do not allow it to
come into contact with the
eyesormouth.Alwaysstore
it in a clearly marked con-
tainer and out of the reach
of children.
Model engine fuel is also
highly flammable. Keep it
away from an 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 en-
closed space. Model engines, like
automobile 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.
••
•
•

4
!
NOTES
Before starting the engine, always check
the tightness of all the screws and nuts
especially those of joint and movable
parts such as throttle arm. Missing
retightening the loose screws and nuts
often causes the parts breakage that is
capable of harming you.
This engine is intended for model cars.
Do not attempt to use it for any other
purpose.
Mount the engine in your model
securely, following the manufacturer's
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 highspeed engines) may
eventually impair your hearing and such
noise is also likely to cause annoyance
to others over a wide area.
The wearing of safety glasses is also
strongly recommended.
Take care that the glowplug clip or
battery leads do not come into contact
with rotating parts. Also check that the
linkage to the throttle arm is secure.
For their safety, keep all onlookers
(especially small children) well back (at
least 20 feet or 6 meters) when
preparing your model for running.
5
!
NOTES
To stop the engine, fully retard the
throttle stick and trim lever on the trans-
mitter, or, in an emergency, cut off the
fuel supply by pinching the fuel delivery
line from the tank.
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 it is rotated over
compression WITHOUT the glowplug
battery being reconnected.
Pull the operating handle straight out
when starting the engine, so that the cord
does not rub against the vehicle body or
engine. This will help prevent the cord
from being damaged by abrasion or
engine heat.
Do not extend the starter cord more than
40cm (16"). Do not abruptly release the
operating handle. Allow the cord to
rewind smoothly while still holding the
handle.
Do not attempt to disassemble the recoil
starter of the 12TG-X and 12TG-PX.
If you do so, the very strong spring inside
will be suddenly ejected. This can be
very dangerous.

6
Piston
Cylinder Liner
Crankshaft
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
Slight taper
When the engine is cold. When the engine is hot.
7
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 any pumped out fuel from
getting into your eyes. Remove the glowplug.
Pump out surplus fuel.
Install the glowplug.

8
This manual handles the following five
versions.
MAX-12TG SERIES INSTRUCTIONS
NOTE
As delivered, the engine has its
carburetor lightly fit into its intake.
Secure it according to the INSTALLATION
OF THE CARBURETOR section.
MAX-12TG
with 12E carburetor
MAX-12TG-X
with 12E carburetor
MAX-12TG-P
with 12D carburetor
MAX-12TG-PX
with 12D carburetor
The 12TG Series engines are developed for
1/10 scale R/C cars. They are rear exhaust
engines designed for sport use.
For easier handling, the engines are
equipped with a newly designed 12E or 12D
carburetor. An O.S. No.8 glowplug is also
supplied with the engines. The 12E and 12D
engines have mild and smooth accelerating
characteristics most suitable for sport
running. Recoil starter incorporated
versions which eliminate the need for a
separate electric starter and starter battery
are also available.
MAX-12TG-P
with 12E carburetor
9
MAX-12TG-PX
MAX-12TG
Heatsink Head
Crankcase
Mounting Lugs
Exhaust
Cover Plate
Carburetor
Type 12E
Crankshaft
BASIC ENGINE PARTS Heatsink Head
Drive Hub
Carburetor
Type 12D
Crankshaft
Crankcase
Mounting Lugs
Exhaust
Starter Handle
Recoil Starter
Assembly No.N1
Rear Adaptor

10
Items necessary for starting
TOOLS, ACCESSORIES, etc.
The following items are necessary for operating the
engine.
FUEL
Generally, it is suggested that the user selects a fuel
that is commercially available for model two-stroke
engines and contains 10-30% nitromethane.
As a starting point, we recommend a fuel containing
20% nitromethane, changing to a fuel containing more
nitro if necessary. When the brand of fuel is changed,
or the nitro content increased, it is advisable to repeat
the running-in procedure referred to in the RUNNING-
IN paragraphs.
Please note that with high-nitro fuels,
although power may be increased for
competition purposes, glowplug
elements do not last as long and
engine life will be shorter.
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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.
!
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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.
GLOWPLUG IGNITER
Commercialy available handy
glowplug heater in which the
glowplug battery and battery leads
are integrated.
11
FUEL PUMP
For filling the fuel tank, a simple, poly-
ethylene "squeeze" bottle, with a suit-
able spout, is required.
FUEL FILTER
To be installed in the fuel line between
fuel tank and carburetor to prevent
foreign matter from entering the
carburetor.
STARTER BOX
For starting the engine.
It is not necessary for 12TG-X
and 12TG-PX.
SILICONE FUEL LINE
Heatproof silicone tubing of approx.
5mm o.d. and 2mm i.d. is required for
the connection between the fuel tank
and engine.
TOOLS
HEX SCREWDRIVER
SCREWDRIVER
Necessary for engine installation.
1.5mm, 2mm, 2.5mm, 3mm
Necessary for carburetor adjustments.
No.1, No.2, etc
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.

12
MAX-12TG, MAX-12TG-P
Standard accessories
Engine Mount Spacer 1piece
Glow Plug No.8 1piece
Exhaust Seal Ring 1piece
MAX-12TG-X, MAX-12TG-PX
Glow Plug No.8 1piece
Exhaust Seal Ring 1piece
INSTALLING THE
GLOWPLUG
Fit washer to glowplug and
insert carefully into cylinder-
head, making sure that it is
not cross-threaded before
tightening firmly.
Install the exhaust seal
ring supplied.
Exhaust
Seal Ring
Glowplug
Socket
Wrench
Washer
Use it when the engine interferes
with the car chassis.
13
CARBURETOR CONTROLS
The Needle-Valve(Adjusted at the factory):
Three adjustable controls are provided on this
carburetor.
For adjusting the mixture strength when the throttle
is fully open.
The Throttle Stop Screw
(Adjusted at the factory):
For setting the minimum idle speed:
For adjusting the mixture strength at part-throttle
and idle speed, to obtain steady idling and smooth
acceleration to mid speed.
The Metering Needle
(Adjusted at the factory):
NOTE: Readjustment may be necessary,
occasionally to allow for changes in fuel formula,
gear ratio or clutch engagement point.
Metering Needle
Throttle Stop
Screw
Needle Valve
Ball Link No.5
Dust Cover
Carburetor Type 12D
Fuel Inlet
Needle Holder

14
Carburetor Type 12E
Mixture Control Screw
Throttle
Stop Screw
Needle Valve
Needle Holder
Fuel Inlet
Throttle Lever
The Needle-Valve(Adjusted at the factory):
Three adjustable controls are provided on this
carburetor.
For adjusting the mixture strength when the throttle
is fully open.
The Throttle Stop Screw
(Adjusted at the factory):
For setting the minimum idle speed:
For adjusting the mixture strength at part-throttle
and idle speed, to obtain steady idling and smooth
acceleration to mid speed.
The Mixture Control Screw
(Adjusted at the factory):
NOTE: Readjustment may be necessary,
occasionally to allow for changes in fuel formula,
gear ratio or clutch engagement point.
(It should be screwed in or out less tan one turn.)
15
INSTALLATION OF THE CARBURETOR
As delivered, the engine has its carburetor lightly fit into
the intake boss. Secure it as follows.
Rotate the retainer screw gently until it stops, then
tighten a further 60-90˚. Do not overtighten the
screw as this will damage the carburetor body.
1.
Rotate the retainer nut
gently until it stops.
Tighten a further 60-90˚
Fuel Inlet
Needle
Holder
Ball Link
Retaining Screw
Loosen the retainer screw, rotate the carburetor to
its correct position and make sure that it is
pressed well down into the intake boss,
compressing the rubber gasket, before
retightening the screw.
NOTE
As delivered, the engine has its carburetor
lightly fit into its intake. Secure it changing its
angle according to the car chassis.
2.
When changing the ball link direction, loosen the
retaining screw with a 1.5mm Hex wrench.
After changed the fuel inlet direction, tighten the
needle holder slowly and gently until it stops. Then,
tighten 45~60 degrees further. Do not tighten further
or the fuel inlet will be distorted, which may result in
fuel leaking.

16
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◆
NOTES CONCERNING THE RECOIL STARTER
REMINDER!
Do not attempt to disassemble the recoil
starter. If you do so, the very strong spring
inside will be suddenly ejected. This can be
very dangerous.
Do not extend the starter cord more than
40cm (16"). Do not abruptly release the
operating handle. Allow the cord to rewind
smoothly while still holding the handle.
Pull the operating handle straight out when
starting the engine, so that the cord does not
rub against the vehicle body or engine.
This will help prevent the cord from being damaged
by abrasion or engine heat.
Try to avoid spilling fuel over the starter unit and its
cord. Some fuels have a detrimental effect on these
parts.
The starter prevents the engine from being rotated
in the wrong direction.The unit will be damaged if you
attempt to force the flywheel in the opposite direc-
tion (i.e. clockwise when viewed from the crankshaft
end).
Starter Handle
16" 40cm MAX!
It is suspected that the engine is over-primed when
the pulling load is too heavy to pull the starter. In this
case, refer to page 7 and TROUBLE SHOOTING
about over priming.
17
GLOWPLUG
The role of the glowplug
Glowplug life
Particularly in the case of very high performance
engines,
glowplugs must be regarded as expendable
items. However, plug life can be extended and engine
performance maintained by careful use, i.e.:
Install a plug suitable for the engine.
Use fuel containing a moderate percentage of
nitromethane unless more is essential for racing events.
Do not run the engine too lean and do not leave the
battery connected while adjusting the needle.
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.
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.
Since the glowplug and fuel combination
used may have a marked effect on per-
formance and reliability, it would be
worthwhile to experiment with different plug types. An
O.S. No.8 glowplug is supplied with the engine. Rec-
ommended O.S. plugs are the No.8 and A5. Carefully
install plug finger-tight, before final tightening with the
correct size plug wrench.

18
ENGINE INSTALLATION
Make sure that the vehicle's engine mounting surfaces
are level and in the same plane. Poor installation may
cause distortion of the crankcase, bearings, etc.,
resulting in erratic running and loss of performance.
Chassis
Chamfer inside edges of bearers.
Do not allow
bottom of
crankcase to
touch chassis.
The recommended screws for securing the engine are
3mm or 4-40 steel Allen hexagon socket type.
If existing holes in the engine mount do not align
perfectly with engine mounting lugs, enlarge them
slightly with a needle-file so that screws are in
alignment with the mounting holes.
Engine Mount
When installing the engine on the chassis, note the
following points.
(Chamfer inside edges of bearers when the engine
mount edges interfere with the engine. Do not
chamfer the engine.)
File
19
JAPAN
NOTE:
When spacers are supplied joined in pairs (see
sketch) separate them as shown.
Either face may be placed downwards.
Avoid forcing the screws. Secure with locknuts. If
the bottom of the recoil starter housing would
otherwise touch the car chassis, install the engine
mount spacers (supplied) between the engine's
mounting lugs and the engine mount. Use the
M3x15 screws provided. With some vehicles, it
may be necessary to make minor trimming
modifications to chassis or body when installing
the engine.
Mount Spacer
Engine Mount Spacer
Separate
Engine Mount
12TG-X AND 12TG-PX INSTALLATION
If existing holes in the engine mount do not align
perfectly with engine mounting lugs, enlarge them
slightly with a needle-file so that screws are in
alignment with the mounting holes.
(Use the mount supplied with the car kit.)

20
STARTING THE ENGINE & RUNNING-IN ('Breaking-in)
PRESSURIZED FUEL SYSTEM
!

Before starting the engine, always check the
tightness of all the screws and nuts especial-
ly those of joint and movable parts such as
throttle arm. Missing retightening the loose
screws and nuts often causes the parts
breakage that is capable of harming you.
Never run your vehicle without installing the air
cleaner. Dust and dirt that may otherwise be drawn
into the engine will rapidly shorten its life.
The somewhat violent changes of vehicle attitude
that occur in off-road running, combined with the
fact that, in buggy type cars, the fuel tank is often
located some distance from the carburetor, means
that fuel 'head' at the carburetor can vary and upset
running.Therefore,it is recommended that a muffler
pressurized fuel feed system be used.
Running- in is a procedure for an engine to come
close to actual running conditions (fuel, r.p.m.,
engine temperature, etc.).
Excessively rich running and prolonged low
speed running should be avoided. Prolonged low
speed running and low temperature running may
result in the oil in the fuel forming varnish that
can result in the piston / liner becoming stuck
together.
Please do not run on a public street, this
could cause serious accidents, personal
injuries and/or propetry damage.
Please do not run near pedestrians or small
children.
Please do not run in small or confined areas.
Please do not run where loud noises can disturb
others, such as hospitals and residential areas.
While Operating RUNNING-IN ('Breaking-in)
21
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Lay the chassis on a stand and start the engine so
that the tires are not in contact with the ground.
The following procedure is suitable when a fuel
containing up to 30% nitromethane is used.
Fill the tank completely with fuel.
Temporarily remove the glowplug to check that it
glows bright red when energized.
Glow Plug Igniter
Pliers
Element glows when
energized.
Replace the plug when the
element does not glow or is
burnt out.
Fuel Pump
Fuel Tank
Do not hold a glowplug with fingers and use
pliers when checking the brightness. Do not
have your face close to the glowplug or boiled
fuel remaining in the coil will burn you.
stand
NOTE:
Be careful not to damage the plug threads when
holding a glowplug with pliers.

22
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→
Turn the needle-valve clockwise until it stops. This
is the fully closed position. Do not force it to turn
further.
Metering needle is set at basic position.
(Refer to P30.)
Needle Valve
Open Close (clockwise)
approx 0.5mm
The carburetor is set as shown below at the
factory. Start the engine as it is.
The needle-valve is set approx. 2.5 turns opened
from the fully closed position.
Approx. 0.5mm open
factory setting
In case of the 12D carburetor
Mixture control screw is set at basic
position. (Refer to P30.)
approx 1mm
In case of the 12E carburetor
Approx. 1mm open
factory setting
Common to 12D/12E carburetors
23
Fuel
Deliver fuel into the carburetor.
Fuel tank side
Note
Check the throttle opening at idle before installing
an air cleaner. After the engine is started, be sure
to install an air cleaner.
If the fuel tank is equipped with a choke button, push
the button to send the fuel to the carburetor. If not,
apply an electric starter to send the fuel to the
carburetor.
Swith on the transmitter and make sure that each
linkage moves correctly.
Fuel tank
choke button
Note
If too much fuel is delivered into the engine, the
engine cannot be started due to over-priming. In
this case, refer to page 7 and TROUBLE SHOOTING
about over-priming.

24
→
→
Now connect glowplug battery lead to heat
the plug filament and start the engine.
In case of the 12TG-X and 12TG-PX
Starter Handle
Pull the starter handle briskly straight out
several times to start the engine.
Start the engine using a starter box, making sure
the engine rotation direction is correct (counter-
clockwise seen from the crankshaft end).
Be sure to install an air cleaner when starting.
In case of the 12TG and 12TG-P
16" 40cm MAX!
Do not extend the starter cord more than 40cm
(16").
Glowplug
Igniter
air cleaner
approx 1mm
approx
1.5mm
Set the needle-valve approx. 2 turns open from the
fully closed position. (Do not close further.)
Set the throttle opening a little wider that the
factory set by adjusting the throttle stop screw.
When the engines does not start
or stops right after started Try the followings.
25
When the engine starts, first allow it to operate in
short runs at the very rich starting settings, with
the glowplug battery still connected and the driving
wheels clear of the ground. The rich mixture will,
under these conditions, provide adequate
lubrication and cooling, indicated by profuse
smoke from the exhaust.
It is vitally important to set the
throttle at the correct position
before attempting to start the
engine. If the engine is allowed to
run with the throttle too far open
under "no load" conditions, it will
rapidly overheat and may be
seriously damaged.
Remember!
RPM High
RPM Low Throttle Stop Screw
Throttle Stop Screw
If the RPM is lowered too much, the engine
stops. Set the idling RPM a little higher when the
engine is new.
Next adjust the idle speed (low engine RPM)
The idle speed should be set so that the car does
not move with the engine running and throttle stick
in the low speed position.
Disconnect the glowplug battery If the car starts
moving (or tires rotate), adjust the throttle stop
screw so that tires may not rotate with steady
idling.

26
Next, disconnect the glowplug battery and try
running the car on the track. If the engine stalls,
open the throttle fractionally, but try to keep the
engine running as rich as possible: if it stops
because of being excessively over-rich, close the
Needle-Valve 15˚ and try again.
Run the car on the track until one tank of fuel has been
consumed, then close the Needle-Valve 15˚ and run
the car for 3 to 5 full tanks of fuel. Repeat this
procedure until approx. 1 liter of fuel have been
consumed, during which time the throttle may be
opened for brief bursts of increased power. If the
engine stops at medium speeds, close the Mixture
Screw 45˚.
Needle
The position of the needle-valve
when starting the engine.
Close the needle-valve approx.
15˚ after running the vehicle for
3 to 5 full tanks of fuel.
Repeat this procedure until
approx. 1 liter of fuel have
been consumed.
Note:
In the event of any major working parts (e.g.
piston/cylinder liner assembly) being replaced or the
fuel being changed, especially to high nitro fuel, the
complete running-in should be repeated.
Warning!
Do not touch rotating parts, engine and silencer
when stopping the engine as they become very hot,
and contact with them may result in a serious burn.
To stop the engine, close the throttle to idle speed
and shut it off completely with the trim lever on the
transmitter then cut off the fuel supply by pinching
the fuel delivery tube to the carburetor.
Fuel
How to stop the engine
27
FINAL ADJUSTMENT
Throttle
Stop Screw
Needle Valve
Metering
Needle
Open Close Close
Open
Needle Valve Metering Needle
More fuel Less fuel More fuel Less fuel
Final adjustment should be carried out only after the running-in has
been completed.
Needle Valve
Throttle
Stop Screw
Mixture Control
Screw
Mixture Control Screw
Needle Valve
Open
More fuel
Close
Less fuel
Open
More fuel
Close
Less fuel
12D carburetor
12E carburetor

28
Run the vehicle (with throttle fully open) over the
longest available straight course, in order to
observe the model's speed. Next return the car to
the starting point, close the Needle-Valve 15˚ and
repeat the run, taking note of the improvement in
performance.
Continue with further runs, gradually reducing the
Needle-Valve setting and aiming to achieve the
highest straight-line speed. Remember, however,
that, if the Needle-Valve is shut down too far, the
engine will overheat and be accompanied by visibly
diminished exhaust smoke and the model will lose
speed. At this point, throttle down immediately, stop
the vehicle and reopen the Needle-Valve 15˚.
With the engine running, close the throttle and
allow it to idle for about five seconds, then reopen
the throttle fully. If, at this point, the engine puffs
out an excessive amount of smoke and the
vehicle does not accelerate smoothly and rapidly,
it is probable that the idle mixture is too rich.
Carry out adjustments patiently, under actual
running conditions, until the engine responds
quickly and positively to the throttle control.
In this case, turn the Metering Needle or Mixture
Control Screw clockwise 15˚.
If, on the other hand, the engine tends to speed
up momentarily and then cut out abruptly when
the throttle is opened, the idle mixture is too lean.
Correct this by turning the Metering Needle or
Mixture Control Screw counter-clockwise 15˚.
Adjust high RPM running. Adjust medium and low RPM running.
Carry out adjustment by 15
degrees at a time for both
closing and opening.
29
With the optimum mixture control position, light
smoke is visible during high speed running,and the
engine rpm increases smoothly during acceleration.
Remember that, if the engine is operated with the
fuel/air mixture slightly too lean, it will overheat and
run unevenly.
As with all engines, it is advisable to set both the
needle-valve and metering needle or Mixture
Control Screw slightly on the rich side of the best
rpm setting, as a safety measure.
If the engine runs too fast with the throttle closed,
the Throttle stop screw should be turned counter-
clockwise to allow the throttle opening to be
reduced.
Finally, beyond the nominal break-in period, a
slight readjustment toward a leaner needle setting
may be required to maintain maximum
performance.
NOTE
The above mentioned needle opening is a guide. It
varies according to the fuel used and silencer.
Usually, when a lower nitro content fuel used, it will
be necessary to close the needle-valve.
Do not close the needle-valve too much or rust will
be generated and the engine will be damaged.
Warning!
Mixture adjustments (whether via the Metering
Needle, or the Needle-Valve) cannot be made
accurately under 'no-load' conditions, which, in
any case, are not advised, since such operation
carries the risk of seriously damaging the engine
through over-revving and overheating.

30
In case of the 12D carburetor
In case of the 12E carburetor
Carburetor Body
Mixture Control Screw
Throttle
Lever
REALIGNMENT OF METERING NEEDLE AND
MIXTURE CONTROL SCREW
In the course of making carburetor adjustments, it
is just possible that the Metering Needle and the
Mixture Control Screw may be inadvertently
screwed in or out too far and thereby moved
beyond its effective adjustment range.
The basic positions can be found by rotating the
Metering Needle until its slotted head is flush with
the ball link body.
Slide Valve
Carburetor Body
Metering Needle
Rotate the Metering
Needle until its slotted
head is flush with the
ball link body. This is the
basic position.
Ball Link
Rotate the Mixture Control
Screw until its slotted
head is flush with the ball
link body.
This is the basic position.
Note:
Readjustment of the needle-valve may be
necessary to allow for changes in fuel formula,
gear ratio, clutch engagement point and muffler.
Also, needle setting may vary to atmospheric
conditions within the day. Readjust it according to
actual engine running.
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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
Air cleaner and silencer inside is dirty.
Clean or replace fuel filter.
Replace cleaner element and clean inside silencer.
Over priming Remove glowplug and pump out 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 servo linkage Connect correctly after setting servo at neutral.
Reverse rotating direction of starter box. Mare sure it rotates counter clockwise seen
from crankshaft side.
Recoil starter slips. Inject cleaner spray into starter cord crevis
on the body.

32
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
Air cleaner and silencer inside is dirty.
Clean or replace fuel filter.
Replace cleaner element and clean inside silencer.
Engine overheated Wait until engine cools.
Incorrect clutch release Adjust the tension of clutch spring.
Glowplug battery disconnected too soon. Do not disconnect plug battery and wait until
r.p.m. becomes stable.
Air bubbles in fuel Install O rings to the tank screws to prevent
bubbles.
33
Cause Corrective action
Cause Corrective action
Unstable idle
Unsuitable glowplug Use suggested glowplug in the instructions.
Unsuitable fuel Do not use extremely high nitro or
low oil content fuel.
Extremely light flywheel Use heavier flywheel
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.
Replace seal ring.
Check the connections and secure them.
Fuel tubing from tank is split or broken. Replace the tubing.

34
Cause Corrective action
Cause Corrective action
Poor response
Deteriorated glowplug Replace glowplug.
Incorrect carburetor settings Readjust low r.p.m. range with metering
needle or mixture control screw.
Incorrect setting of transmitter Exponential function.
Check the transmitter setting.
Poor r.p.m. drop
Throttle position open too far. Close throttle stop screw to adequate position
to lower idle r.p.m.
Carburetor not fully seated Install carburetor securely.
Incorrect linkage Make sure the throttle servo linkage does not
bind and is connected correctly.
Metering needle or mixture control screw
closed too far.
Open the metering needle or mixture control
screw a little.
35
CARE AND MAINTENANCE
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.
Afterwards,energize the glow-plug and try to restart
the engine, to burn off any fuel that may remain
inside the engine. Repeat this procedure until the
engine fails to fire. Do this while the engine is still
warm.
Care and maintenance after the running is very
important. Be sure to carry out the following
procedures.

36
Then, inject some after-run oil into the engine, and
rotate the engine with an electric starter or the
recoil starter for 4 to 5 seconds to distribute the oil
to all the working parts.
Finally, when cleaning the exterior of the
engine, use methanol. Do not use gasoline
or any petroleum based solvent that might
damage the silicone fuel tubing.
Note:
Do not inject a petroleum based after-run oil into
the carburetor as this may cause the O-rings
inside the carburetor to deteriorate. These
procedures will reduce the risks of starting
difficulties or corrosion after a period of storage.
37
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 to the pickup 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.
Dirt and dust may lodge in marked places.
CHECKING THE ENGINE
If the engine suffers a loss of performance after a
long period of running it may be due to the wearing of
parts. It is suggested that the worn parts be replaced
when the following symptoms are detected.
Engine sound changes and easily overheats.
Power has dropped considerably.
Idle is unstable and/or engine tends to stop
at idle.
In most cases, ball bearings, cylinder & piston assembly,
connecting rod and/or crankcase have become worn
out or abnormal. Check the parts carefully and replace
them if necessary.

38
C.M3x16
1
2
3
5
4
6
7
89
10
11
12
14
13
15
C.M2.6x7
16
MAX-12TG ENGINE EXPLODED VIEW
Type of screw
C...Cap Screw M...Oval Fillister-Head Screw F...Flat Head Screw N...Round Head Screw S...Set Screw
39
1 2 3 4 5 6 7 8 9
10 11 12 13 14 15 16
21414000 21413000 21536000 21817000 21415000 21428000 25381701 20810007 21458000 22631020 21411010 21931000 21412020 21411400 21417000 23763000 71608001 21427200

MAX-12TG ENGINE PARTS LIST
The specifications are subject to alteration for improvement without notice.
Description
Code No.
No.
Heatsink Head Cylinder & Piston Assembly Piston Pin Piston Pin Retainer (2pcs.) Connecting Rod Carburetor Complete (Type 12E) Carburetor Retainer Assembly Propeller Nut Drive Hub Crankshaft Ball Bearing (Front) Crankcase Crankshaft Ball Bearing (Rear) Crankshaft Gasket Set Cover Plate Screw Set Glow Plug No.8 Exhaust Seal Ring