2001-2002 Yamaha 50HP F50Z/T50Z Ouboard 4-stroke engines service manual, Page 15Get this manual
Technical tips Carburetor operation 1Idle and low-speed operation Since the vacuum at the venturi is low when the throttle valve is opened slightly, the main nozzle does not supply any air-fuel mixture to the engineWhen the engine is operating at idle, the fuel that passes through the pilot jet and the air that passes through the pilot air jet mix, enabling the air-fuel mixture that has been regulated by the pilot screw to be fed through the pilot outletBecause the throttle valve opens slightly when the engine is operating at low speeds, air-fuel mixture also starts to be fed from the bypass holes