Subaru Robin EX30 - Manual (Page 52)

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12-1 SPECIFICATIONS
12. CARBURETOR
12-2 FUNCTIONS AND CONSTRUCTION
12-2-1 FLOAT SYSTEM
The fl oat chamber is located below the carburetor body. Through the operation of the fl oat and the needle valve,
the fl oat chamber maintains a constant fuel level while the engine is working.
The fuel fl ows from the tank into the fl oat chamber through the needle valve. When the fuel rises to a specifi c
level, the fl oat rises. When the buoyancy of the fl oat is balanced with the fuel pressure, the needle valve shuts off
the fuel passage, thereby maintaining the fuel at the predetermined level.
12-2-2 PILOT SYSTEM
The pilot system supplies fuel to the engine during idling and low-speed operation.
Fuel is initially metered by the main jet and then metered once again by the pilot jet. At the pilot jet, the fuel is
mixed with air metered by the pilot air jet and then 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.
12-2-3 MAIN SYSTEM
The main system feeds fuel to the engine at medium and high speed operation.
Fuel is metered by the main jet and fl ows 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.
12-2-4 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.
A/C Type Urethane foam element
Main Jet 98.0
Pilot Jet 40.0
Pilot Screw Turning 1-1/2