Honda BF35A-BF45A Outboard Motors Shop Manual., Page 231Get this manual
At tilt lock When the tilt lever is the "LOCK" position, the piston does not move as the change valve cam is also in the "LOCK" position and the oil passage closesTILT LEVER
CHANGE VALVE CAM
At tilt updown
When the tilt lever is set in the "FREE" position, the change valve cam lifts the check valve push rod and opens the check valve, resulting in the oil flowing into the oil passageWhen tilting up the outboard motor, the oil in the oil chamber enters the oil chamber II and the outboard can be tilted up easily because of the nitrogen gas in the nitrogen gas chamberWhen tilting down the outboard motor, the oil in the oil chamber 1flows the oil chamber and the outboard motor lowers by its own weight