Carburetor - Subaru EX35 Service Manual

13. CARBURETOR

13-1 SPECIFICATIONS
A/C Type
Main Jet
Slow Jet
Venturi Bore
13-2 FUNCTIONS AND CONSTRUCTION
13-2-1 FLOAT SYSTEM
The float chamber is located below the carburetor body. Through the operation of the float and the
needle valve, the float chamber maintains a constant fuel level while the engine is working.
The fuel flows from the tank into the float chamber through the needle valve. When the fuel rises to a
specific level, the float rises. When the buoyancy of the float is balanced with the fuel pressure, the
needle valve shuts off the fuel passage, thereby maintaining the fuel at the predetermined level.
13-2-2 SLOW SYSTEM
The slow system supplies fuel to the engine during idling and low-speed operation.
Fuel is initially metered by the main get and then metered once again by the slow jet.
The fuel / air mixture is fed to the engine through the pilot outlet and the bypass.
During idling, fuel is fed to the engine mainly through the pilot outlet.
13-2-3 MAIN SYSTEM
The main system feeds fuel to the engine at medium and high speed operation.
Fuel is metered by the main jet and flows into the main nozzle. Air metered by the main air jet is
mixed with fuel through the bleed holes of the main nozzle. The fuel/air mist is injected into the
Venturi and mixed once again with air from the air cleaner. This fuel/air mixture is now of optimum
concentration and is fed into the combustion chamber of the engine.
13-2-4 CHOKE SYSTEM
The choke system is for easier start of the engine in cold weather conditions.
When the engine is started with a closed choke, the negative pressure applied to the main nozzle
increases. This causes a larger amount of fuel to be drawn into the carburetor, which in turn makes it
easier to start the engine.
EX35
URETHANE
109
40
(mm) 17
EX40
DUAL URETHANE
107 113
44 49
- 54 -
DUAL
110
51
19