CARBURETORS (Can't.)
PI
LOT SYSTEM
The
pilot
system
is
designed
to
deliver gasoline during idling and
low-speed driving.
Fuel
for
idling
is
measured by the
pilot
jet, mixed
with
the air,
regulated
with
the air screw, mixed
again
with
the air
from
the
by-pass,
and
delivered
to
the engine through the
pi
lot
outlet.
The concentration
of
fuel-air
mixture
for
idling
is
determined
by
the air screw.
When
the air screw
is
closed, the amount
of
air
is
reduced
and
the fuel-air mixture
is
enriched. When the air
screw
is
opened, the amount
of
air increases
and
the fuel-air
mixture
is
lean.
When
the
throttle
valve opens slightly during low
speed
driving,
gasoline injects through the by-pass in addition
to
the fuel-air
mixture
from
the
pilot
outlet
to
secure smooth operation
of
the engine.
When
the
throttle
valve opens wider, approximately
above
1/8
of
the diameter
of
the main bore, gasoline injects
through the
needle jet. The adjustment
of
the
time
and amount
of
injection
from
the needle
jet
is
chiefly performed
by
the
cutaway furnished on the side
of
the air cleaner
of
the
throttle
valve.
MAIN
SYSTEM
The main system
is
designed
for
delivering fuel between
low
speed
driving
and
high
speed
driving.
The
fuel during the low
speed
driving
is
delivered
from
the
pilot
system
and
the main system. During intermediate
speed
driving (the opening
of
the
throttle
valve
is
above 1/4), the
fuel
is
largely delivered
from
the main system. The fuel during
intermediate
speed
driving flows
into
the needle
jet
through
the main
jet
and
mixes
with
the air measured
by
the air-jet
to
make a fine spray
of
fuel-air
mixture
of
good quality.
70
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