2001 Edition Yamaha F225A and LF225A Outboards Service Manual, Page 213Get this manual
Shimming (counter rotation model) Selecting the reverse gear shims
1Calculate the specified value (M0) as shown in the examples belowNOTE: Measure the bearing retainer at three points to find the clearance average4Select the reverse gear shim(s) (T1)
NOTE: "F" is the deviation of the lower case dimension from standardThe "F" mark is stamped on the trim tab mounting surface of the lower case in 0.01 mm unitsIf the "F" mark is unreadable, assume that "F" is zero and check the backlash when the unit is assembledCalculation formula: Specified value (M0)30.60F100 mm Example: If "F" is (+5), then M030.60(+5)100 mm30.600.05 mm30.65 mm If "F" is (3), then M030.60(3)100 mm30.60 0.03 mm30.57 mm 2Set the thrust bearing to the bearing retainer as shown3Turn the thrust bearing two or three times to seat the bearing retainer, and then measure the bearing height (M)