Honda BF8, BF9.9 and BF10 Outboard Motors Shop Manual., Page 359Get this manual
11)Loosen the manual valve by turning it turns or morel2)lnstall the drive joint in the position of the gear pump assembly as shown13) Fill the gear pump chamber with the fresh ATF up to the upper edge of the chamberIf the ATF in the valve body contains air bubbles, remove the air bubbles using an oil bottle or equivalent tool[DRIVE JOINT
Do not pour ATF into the valve body gear pump chamber quicklyPour the fluid slowlyTrapped air in the system causes faulty operationRemove the air bubbles in the fluid securely