Honda BF20A-BF25A, BF25D-BF30D Outboard Motors Shop Manual., Page 268Get this manual
2CARBURETOR ZAUTION Running the outboard motor without sufficient cooling water will damage the water pump and overheat the engineBe sure that water flows from the cooling system indicator while the engine is runningIf not,stop the engine and determine the cause of the problem
Idle speed
1) Remove the propellerSeal the right and left water screens and the water bottom screen with gummed cloth tape or equivalentStart the engine while distributing the water throughout the outboard motor by using the flushing plug (optional part) or with the outboard motor soaked in the outboard test tank2) Remove the engine cover[THROTTLE STOP SCREW
3) After the engine speed stabilizes, adjust the idle speed to the specified speed by turning the throttle stop screwSpecified idle speed (in neutral)
950 50 min-1 (rpm)
If the idle speed is not stabilized, perform the carburetor synchronization (see below)[10 mm PLUG (3)