O.S. Engines 70SZ-H - Manual (Page 8)

14
BASIC POSITION OF MIXTURE CONTROL VALVE
(Mixture Control Screw)
Thick
Mixture Control Valve
MIxture Control Screw
Lean
As delivered, the Mixture Control Screw is positioned
at 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 may vary due
to various factors such as climatic conditions, fuel,
muffler, main rotor, weight of the model, gear ratio,
etc. Therefore, the Mixture Control Screw position
will vary with each model and set- up, and it is normal
if the Mixture Control Screw position is off center.
86 degrees
As shown in the sketch, the carburetor has
graduation marks. 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 86
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.
Graduations on the carburetor body
Carburetor Rotor
Carburetor Body
Fully closed position
Fully opened position
15
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:
at basic position when the engine leaves the
factory.
exactly one turn open from the fully closed
position.
Medium Speed needle-valve:
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 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.
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.