2000-2005 Yamaha F40B Outboard Service Manual, Page 96Get this manual
.1CONTROL SYSTEM (7) Turn the throttle valve adjusting screws so the vacuum pressure of carburetors #1, and #2 are within the specified variationsVacuum variation #3: Base valve #2: #3 mm Hg (6.7 bar, 0.2 in Hg) #1: #310 mm Hg (13.3 bar, 0.4 in Hg)
EXAMPLE
If #3 valve is 300 mm Hg, #2: #3mm Hg300= 295 mm Hg: #310m30010290 mm Hg (8) Readjust the engine idling speed to the specification