Yamaha F100B F100C Outboards Factory Service Manual, Page 92Get this manual
Fuel system
6Turn the throttle valve adjusting screws to adjust the vacuum pressure of carburetors #1, #2, and #3 to the same vacuum variation as carburetor #4
Fuel system
6Turn the throttle valve adjusting screws to adjust the vacuum pressure of carburetors #1, #2, and #3 to the same vacuum variation as carburetor #4