9-5 CARBURETOR

9-5-l FUNCTION AND STRUCTURE

(1)Float System

The float chamber is located directly under the carburetor. The float and the needle valves maintain a constant fuel level inside the float chamber while the engine is running.

The fuel in the tank flows into the float chamber through the needle valve. When a certain quantity of the fuel enters the chamber the float rises and when the buoyancy of the valve balances with the fuelin-flow pressure the needle valve is interrupted to keep the fuel at the correct level.

(2)Pilot System

The system controls the fuel supply for engine speeds ranging from idling to low-speed running. The fuel flows through the main jet into the pilot jet where the fuel quantity is measured. Then, the fuel is mixed with air measured in the pilot air jet, and is supplied from the pilot outlet by- pass to the engine. Fuel for idling is supplied mainly from the pilot outlet.

(3)Main System

The system supplies fuel for medium and high speed operations. The fuel is measured in the main jet, and then flows into the main nozzle. Air measured in the main air jet mixes with the fuel from the bleed hole of the main nozzle bursting into the main bore in the form of gas mist. Then it is again mixed with air inducted through the air cleaner to get appropriate density, and finally it is supplied to the engine.

(4)Choke System

The choke system helps start the engine in cold weather.

When the choke is closed and the engine is started, the load to the main nozzle increases and inducts a large quantity of fuel, thus facilitating starting.

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Subaru Robin Power Products R1200 service manual Carburetor