1998-2006 Yamaha F20/F25 Outboards Service Manual, Page 205Get this manual
[LOWR'" _ SHIMMING 6-19 SHIM SELECTION (FOR USA AND CANADA) 6-19 Pinion gear shim 6-19 Forward gear shim 6-21 Reverse gear shim 6-23 SHIM SELECTION (EXCEPT FOR USA AND CANADA) 6-25 Pinion gear shim 6-25 Forward gear shim 6-27 Reverse gear shim 6-28 BACKLASH MEASUREMENT 6-30 Forward gear 6-30 Reverse gear 6-32