Honda BF35A-BF45A Outboard Motors Shop Manual., Page 406Get this manual
12) Remove the bottom piece from the cylinderRemove and discard the O-ringReplace the O-ring with new one during reassembly [I] BOTTOM PIECE
Clean the threads of the bottom piece14) Remove the piston and free piston from the cylinderRemove and discard the O-rings and discard themReplace the O-rings with new ones during reassembly
[41 151 FREE PISTON PISTON ROD
161 CYLINDER
VALVE BODY