Honda BF35A-BF45A Outboard Motors Shop Manual., Page 234Get this manual
From the set angle to full open From the operation angle where the diaphragm is at the full stroke position the fully open throttle, the throttle opener cam interconnected to the diaphragm via the assist spring operates, which is called the lost motion mechanism, and the diaphragm does not move further 121
DIAPHRAGM
THROTTLE OPENER CAM
ASSIST PIATE
1 Set angle 3
1 Full open 6
At quick close When the throttle is moved quickly to the fully closed position, the leak jet in the dashpot check valve restricts the air flowing into the diaphragm and the opener cam return spring absorbs the return force of the throttle cam to allow the throttle cam close slowly and, thereby, to prevent incomplete combustion of the engine