Honda Outboards BF40A/BF50A Service Manual, Page 408Get this manual
BF40A-BF50A 6) Remove the spool valve cap using commercially available 2.8 mm driver bit[1SPOOL VALVE CAP
[2] DRIVER BIT, 2.8 mm (Commercially available)
7) Apply small squirt of air pressure to the oil hole in the spool valve cap to remove the valve BRemove the valve from the spool valve capRemove the O-rings from the spool valve cap and valve and discard themReplace the O-rings with the new ones during reassembly