2001-2002 Yamaha 50HP F50Z/T50Z Ouboard 4-stroke engines service manual, Page 17Get this manual
Technical tips 3High-speed operation When the throttle valve approaches its fully open position, the fuel that has been regulated by the main jet and the air that has been regulated by the main air jet are mixed in the main nozzleThe resultant mixture is then sprayed by the main nozzle into the venturiThe air-fuel mixture that is sprayed through the venturi is then fed into the engine