Rotax 912-UL - BING Constant Depression Carburetor Type 64.3; 1) Description of Carburetor; 2) Attachment; 3) Fuel Supply Control

7.15) BINGconstant
depression carburetor type
64-3
7.15.1)
General
data
The BING
constant depression carburetor type
64-3 comprises
a
cross
draught
butterfly-valve
carburetor with variable choke tube, double-float system arranged
centrally
below the carburetorventuri and a
rotary-valve
type starting carburctor. It
features
a throttle slide which
is
suspended from
a
roll-
diaphragm and
projects
into
the
venturi. It
changes the smallest cross-section
("choke
tube") of the venturi
as a
function
of the vacuum at this
point.
The
throule
valve
diameter
is
36
mm
(1,42
in.).
7.L5.2) Attachmcnt
The
carburetor is secured to
the
engine
using
a
43 mm
(1,7
in.)
diameter
push-on
connection
which
takes a
flexible
connecting
piece
with clamps. On
the
intake
side
the
carburetor is
provided
with a socket having
a
diameter
of 50
mm
(1,97
in.)
and
a length of 12
mm
(0,47
in.)
for
connecting
an air filter
or
intake
silencer.
7.1.5.3)
Fuel
supply control
The float
(12)
of
the carburetor
consists of two
plastic
float
elements
joined
by
a
metal hinge. The float is
arranged centrally below the carburetor choke
tube so that
the carburetor
can
be
tilted very
far in
all directions without
impairing
operation. The
object
of the
float
is to
maintain
the
fuel
level in the
float
chamber
(15)
constant.
When
the
fuel has
reached
a specified
level
in the float chamber,
then the
float
(12)
mounted
on
pin
(14)
is lifted
until the
float needle
(10)
is
pressed
against
the seat of
the
float needle
valve,
thus
preventing
any
further
supply
of
fuel. When
the engine
draws
in fuel
from the
carburetor, the
level in
the
float
chamber
(15)
drops
and so
does
the
float.
The float needle then
opens
the valve again and allows fuel
to
flow
in
from
the
tank.
The float needle
valve
regulates
the fuel supply
in
conjunction with
the
float
but
it
does not
act as a stop valve when the engine is
at
standstill. Minute foreign
bodies may
be
deposited between valve seat and
needle
tip, thus
preventing
complete
closure
of
the valve.
When stopping the engine, thereforc,
the fuel cock
on the tank should
always be closed. In addition the fuel should be
filtered
before
it reaches
the
carburetor. The filter should be selected so that
foreign
bodies
greater
than 0,1 mm
are
filtered out
and the
fuel
supply
is not impeded
to
too
great
an extent.
The
float needle
(10)
contains a
spring-loaded
plunger
which
contacts the
float
hinge.
This
absorbs
vibrations
on the
float
(12).