Honda Outboards BF40A/BF50A Service Manual, Page 419Get this manual
BF40A-BF50A 9) Apply ATF to the lower end of the cylinder and install the cylinder to the bottom piece
[2] OUTER TUBE LOWER END
10) Set the cylinderpiston assembly vertically on the vise by holding the bottom piece CAUTION: Take care not to tighten the vise too tight as it damages the bottom piece11)Pour the fresh ATF into the cylinder up to the top edge of the cylinder[1CYLINDER