2000-2005 Yamaha F40B Outboard Service Manual, Page 340Get this manual
_ BACKLASH
Do not install the water pump components when measuring the backlashMeasure both the forward and reverse gear backlashesIf both the forward and reverse gear backlashes are larger than specification, the pinion gear may be too highIf both the forward and reverse gear backlashes are smaller than specification, the pinion gear may be too low
MEASURING THE FORWARD GEAR BACKLASH
1Measure: Forward gear backlash Out of specification -7 AdjustForward gear backlash 0.1-0.3 mm (0.004-0.012 in) Measuring steps (1) Set the shift rod into the neutral position