Carburetor - Subaru ER12 Service Manual

11. CARBURETOR

11-1 SPECIFICATIONS
A/C Type
Main Jet
Pilot Jet
Venturi Bore
11-2 FUNCTIONS AND CONSTRUCTION
11-2-1 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 .
11-2-2 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 .
11-2-3 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 .
11-2-4 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 .
Float type
Single
# 66 .3
# 30
φ 12
(mm)
- 50 -