Yamaha F115A Service Manual page 438

LOWR
BACKLASH (REGULAR ROTATION MODELS)
2. Adjust:
• Reverse gear shim
Remove or add shim(s).
Reverse gear
backlash
Less than
0.50 mm (0.020 in)
More than
0.73 mm (0.029 in)
M: Measurement
6-69
E
Shim thickness
To be increased by
(0.62 – M) × 0.58
To be decreased by
(M – 0.62) × 0.58