Bing Constant Depression Carburetor Type 64.3; 1) Description Of Carburetor; 2) Attachment; 3) Fuel Supply Control - Rotax 912-UL Repair Manual

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).