Yamaha Marine Outboards Factory Service / Repair/ Workshop Manual 225G 250B L250B, Page 198Get this manual
SHIMMING (REGULAR ROTATION MODELS) (FOR USA AND CANADA)
(2) Install the shimming gauge, bearingand shim(s) 1Shimming gauge YB-06439 NOTE: If the original shim(s) is unavailable, start with 0.50-mm shim(3) Measure the specified measurement (M)