User Manual

28
During subsequent flights, the needle-valve
can be gradually closed to give more power.
However, if the engine shows signs of
running too lean, the next flight should be
set richer. After a total of ten flights, the
engine should run continuously, on its
optimum needle-valve setting, without loss
of power as it warms up.
After the completion of the running-in adjust
the carburetor at optimum setting referring
to MIXTURE CONTROL VALVE
ADJUSTMENT section and SUBSEQUENT
READJUSTMENT section.
4.
5.
As the needle-valve is closed slowly and grad-
ually, the engine r.p.m. will increase and a
continuous high-pitched exhaust note, only,
will be heard. Close the needle-valve 10-15
degrees and wait for the change of r.p.m.
After the engine r.p.m. increases turn the nee-
dle-valve another 10-15 degrees and wait for
the next change of r.p.m. As the speed of the
engine does not instantly change with needle-
valve readjustment, small movements, with
pauses between, are necessary to arrive at the
optimum setting.
Optimum needle setting(1)
Optimum needle setting(2)
Slowly advance the throttle to its fully open
position, then gradually close the needle-valve
until the exhaust note begins to change. (4-
cycle to 2-cycle)
29
20-45
degrees
Needle-valve adjustment diagram
This diagram is for reference
purposes only.
Actual needle positions may
differ from those shown.
Note :
Practical best(optimum) needle-valve setting
Exhaust note starts to change.
Disconnect battery
leads from glowplug at
about this point.
Clear, high-pitched two-stroke
exhaust note
Maximum rpm
setting("Lean").
STARTING
"Rich" needle-valve
setting when starting
the engine.
The engine may stop if
the battery leads are
disconnected from the
glowplug while the
engine is running rich.
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Intermittent, high-pitched
two-stroke note
superimposed
on low "four-stroke"
sound.
Note: Although this is a two-stroke engine it fires like a four-stroke at these
rich needle-valve settings-i.e. ignition of the fuel charge takes place at
every fourth stroke of the piston instead of at every second stroke.
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