12XZ
O.S. SPEED 12XZ Spec.
It is of vital importance, before attempting to operate your
engine, to read the general 'SAFETY INSTRUCTIONS
AND WARNINGS' in the following section 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.
SAFETY INSTRUCTIONS AND WARNINGS ABOUT YOUR O.S. ENGINE
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 or abused. As owner, you, alone, are
responsible for the safe operation of your engine, so
act with discretion and care at all times. If at some
future date, your O.S. engine is acquired by another
person, we would respectfully request that these
instructions are also passed on to its new owner.
The advice which follows is grouped under two
headings according to the degree of damage or
danger which might arise through misuse or neglect.
WARNINGS
These cover events which might involve serious
(in extreme circumstances, even fatal) injury.
NOTES
These cover the many other possibilities, generally less
obvious sources of danger, but which, under certain
circumstances, may also cause damage or injury.
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.
When the engine is cold.
NOTES WHEN APPLYING AN ELECTRIC STARTER
ENGINE CONSTRUCTION
Near TDC
Cylinder
Liner
Crankshaft
Slight taper
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.
Piston
When the engine is hot.
WARNINGS
Model engine fuel is poisonous. Do not
allow it to come into contact with the eyes
or mouth. Always store it in a clearly marked
container and out of the reach of children.
Model engine fuel is also highly flammable.
Keep it away from open flame, excessive
heat, sources of sparks, or anything else
which might ignite it. Do not smoke or allow
anyone else to smoke, near to it.
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 enclosed space.
Model engines, like automobile engines, exhaust
deadly carbon-monoxide. Run your engine only in
an open area.
NOTES
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 manufacturers' recommendations, using
appropriate screws and locknuts.
NOTES ON OPERATION
ABOUT THE WARRANTY
Since this is a special SPEED version, individual
special parts are available only for limited period
(one year after finishing the production).
Also, the engine is free of warranty due to damage
and/or wear occurred during running.
While Operating
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.
NOTE
As delivered, the engine has the carburetor
lightly fit into its intake. Secure it changing its
angle according to the car chassis.
ABOUT THE ENGINE
The O.S. SPEED 12XZspec is a high performance
engine meeting IFMAR specification produced by O.S.’s
SPEED TEAM technicians.
Major parts such as cylinder & piston assembly, crankshaft
and crankcase are have been refined to have a powerful
potential equal to more expensive specially tuned or
modified engines. Also, it employs an outer head that has
many drilled holes for lighter weight and better cooling, and
a ceramic rear ball bearing for lower friction loss.
Standard accessories
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.
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.
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.
TOOLS, ACCESSORIES, etc.
The following items are necessary for operating the engine.
Items necessary for starting
FUEL
Generally, it is suggested that the user selects a fuel that is
commercially available for model two-stroke engines 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 shortened.
FUEL FILTER
To installed in the fuel line between fuel
tank and carburetor to prevent foreign
matter from entering the carburetor.
GLOWPLUG IGNITER
Commercialy available handy glowplug
heater in which the glowplug battery and
battery leads are integrated.
STARTER BOX
For starting the engine.
FUEL PUMP
For filling the fuel tank, a simple, polyethylene
"squeeze" bottle, with a suitable spout, is
required.
O.S. SPEED SILICONE FUEL LINE
The connection between the fuel tank and the engine.
2.5mm ID
(optional extra)
TOOLS
O.S. SPEED DRIVER TOOLS
(optional extra)
Glow Plug RP6
T-type head (Turbo head) 1piece
Exhaust Seal Ring 1piece
Dust Cap Set
3mm 1piece 16mm 2pcs.
O.S. SPEED FLYWHEEL KEY
O.S. SPEED
CLUTCH WRENCH & ADJUSTER
O.S. SPEED FLYWHEEL PULLER
O.S. SPEED PLUG WRENCH
BASIC ENGINE PARTS
Outer Head
Carburetor
Type (12F2-B)
Exhaust
Cover Plate
Crankshaft
Mounting Lugs
Crankshaft Bearing (Front)
INSTALLATION OF THE STANDARD ACCESSORIES
Installing the glow plug. Insert RP6 plug supplied into
heatsink-head carefully, making sure that it is not
cross-threaded before tightening firmly.
(All the O.S. T-Type plugs including the RP6 are not
supplied with a washer.)
Install the exhaust seal ring
supplied.
CARBURETOR CONTROLS STANDARD POSITIONS
(POSITIONS WHEN THE ENGINE LEAVES THE FACTORY)
Four adjustable controls are provided on this
carburetor.
Carburetor Reducer
Throttle Stop
Screw
Themo Insulator
The Needle-Valve:
For adjusting air/fuel ratio (air-fuel mixture) at maximum
rpm (fully opened throttle).
Close(Clockwise)
Open
(Counter-clockwise)
[Standard Position]
2.5 turns opened from the fully closed position.
[Fully closed position]
Turn the needle-valve clockwise until it stops.
This is the fully closed position.
Do not force it to turn further.
The Mixture Control Valve:
For adjusting acceleration feeling.
(Adjusting range should be within ±1 turn.)
Mixture Control Valve
[Standard Position]
Flush with the carburetor body.
Mixture Control Valve
Carburetor Body
Crankcase
Needle Valve
Ball Link
Needle Valve
Exhaust
Seal Ring
Dust Cover
Metering Needle
The Metering Needle:
For adjusting idle and acceleration feeling.
Ball Link
[Standard Position]
Flush with the ball link body.
Metering Needle
Carburetor Body
The Throttle Stop Screw:
For setting the minimum idle speed:
Carburetor Body
Note:
Sketch shows the carburetor reducer removed.
NOTE: While the Mixture Control Valve and the
Metering Valve are set at the standard position
when the engine leaves the factory, readjustment
may be necessary, occasionally to allow for
changes in fuel formula and climatic conditions
Readjust the controls only when satisfactory
results cannot be obtained with the standard
positions following the instructions mentioned in
the “CARBURETOR ADJUSTMENT” section.
INSTALLATION OF THE CARBURETOR
As delivered, the engine has its carburetor lightly installed
in the intake boss. Secure it as follows.
Retaining
Screw
Loosen the retainer screw, rotate the carburetor to its
1.
correct position and make sure that it is pressed well
down into the intake boss, compressing the rubber
gasket, before retightening screw.
Rotate the retaining screw gently until it stops, then
2.
tighten a further 120-180 , and no more.
Do not overtighten the screw as this will damage the
thermo insulator.
Note
Be careful not to damage the O rings when
removing the carburetor retainer from the engine.
First, remove the Retaining screw, then pull out
each retainer. Do not push the retainers in or the O
rings will get damage.
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.
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.
Chamfer inside edges of bearers.
Slide Valve
[Standard Position]
Approx 0.5mm
Slide Valve
Rotate the retainer screw
gently until it stops.
Tighten a further
120-180
Pull out
"O" Ring
"O" Ring
Do not allow bottom
of crankcase to
touch chassis.
STARTING THE ENGINE & RUNNING-IN ('Breaking-in)
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 becoming gelled and the
piston/liner becoming stuck together.
PRESSURIZED FUEL SYSTEM
It is recommended that a muffler pressurized fuel
feed system be used so that the fuel may be stably
fed to the carburetor.
The following procedure is suitable when a fuel
containing 20% nitro-methane is used.
Set the carburetor controls at the standard positions
1.
(positions when the engine leaves the factory.)
Switch the transmitter and make sure that each
2.
linkage moves correctly.
Make sure rotating direction of the starter box is
3.
correct (counter-clockwise seen from the front edge
of the crankshaft), and turn the engine with the
starter box to draw fuel into the engine.
Connect glowplug battery lead to heat the plug and
4.
start the engine with the starter box.
When the engine does not start or stops right after
being started, try the followings.
Set the needle-valve approx. 2 turns open from the
fully closed position. Do not force the needlevalve to
turn beyond a lightly closed position.
Set the throttle opening a little
wider (approx. 1mm) than the
standard setting by adjusting
the Throttle Stop Screw.
5.
When the engine starts, warm it up by repeatedly
increasing the rpm to medium speed and back
again to a fast idle with the mixture set very rich,
glowplug connected, and the driving wheels clear of
the ground. The rich mixture will provide adequate
lubrication and cooling, indicated by profuse
exhaust smoke.
Attention:
It is vitally important to set the
throttle at the correct position
before starting the engine. If
the engine is allowed to run
with the throttle too far open
under ''no load'' conditions
(i.e. with the driving wheels not in contact with the
ground) it will rapidly over-heat and may be
seriously damaged.
6.
When the engine is warmed up, disconnect the
glowplug battery and try running the car on the
track. If the engine stops soon after running at
around mid speed, the mixture is too rich. Close the
needle-valve 15°.
If the engine still stalls, close the metering needle
15°. Run the car on the track until one tank of fuel
has been consumed, then close the needle-valve
very little (within 10°).
7.
Repeat this procedure (close needle-valve very little
after one tank of fuel has been consumed) until approx.
2 liters of fuel have been consumed, extending gradually
the full throttle running time at the straight. Carefully
observe the exhaust smoke.
Be sure to run the engine with visible white smoke at
all times. If the smoke is not visible, the needle-valve
is closed too far.
Now the RUNNING-IN (Breaking-in) is completed.
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.
How to stop the engine
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.
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.
approx 1mm
Fuel
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