Honda BF8, BF9.9 and BF10 Outboard Motors Shop Manual., Page 355Get this manual
8) Apply ATF to new O-ring, and install it in the lower groove in the outer tube9) Apply ATF to the new dust sealHolding it with your fin-
gers so that it shapes "U1'and install it in the upper groove in the outer tube
DUST SEAL
10)Attach thin sealing tape around the threads at the end of the piston rod11) Install the cylinderpiston assembly in the outer tube" If it is hard to install the piston rod end in the outer tube, apply ATF to the piston rod end, then insert the piston rod into the outer tube by turning the outer tube8 Take care not to push the piston rod into the cylinder with force8 When the piston rod is pushed into the cylinder with force, push in the free piston in the cylinder as full as it goes with the threaded part of the piston rod facing down and by holding the outer tube and cylinder securely12)After installation, remove the sealing tape from the threads at the end of the piston rod