O.S. Engines 12XZ Speed Spec II - Manual (Page 10)

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STARTING THE ENGINE & RUNNING-IN ('Breaking-in)
PRESSURIZED FUEL SYSTEM
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 break-
age 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 the 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 becoming gelled and
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)
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The following procedure is suitable for these
engines when the O.S. T-1060 tuned silencer
and a fuel containing 20% nitromethane are
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.
Turn the needle-valve clockwise until it stops. This
is the fully closed position. Do not force it to turn
further.
Metering needle and mixture control valve
are set at basic position. (Refer to P25.)
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.
Throttle is set approx. 0.5mm open.
Approx. 0.5mm open
factory setting with the
reducer removed