Honda BF50 (5HP), BF5A Outboard Motors Shop Manual 2014, Page 68Get this manual
BF50-BF5A IMPELLER PUMP IMPELLER HOUSING ASSEMBLY: Align the flat surface in the center of the pump with the flat side of the pinion shaft
6 28 mm HEX BOLT (4) ASSEMBLY:
WATER TUBE SEAL RING
Apply Hondaflne Anaerobic thread lock to the thread before Installing
IMPELLER PUMP ASSEMBLY:
FLAT SIDE
Check for wear or cracksInstall the Impeller In the pump housing while turning it counterclockwise