Yamaha F25 - Technical Features and Description; Engine Control System Overview; Power Unit Features; Lubrication, Cooling, and Exhaust Systems

TECH
FEA
2
Technical features and description
Engine control system.............................................................. 2-1
Outline ........................................................................................ 2-1
Ignition control system............................................................. 2-3
Ignition timing control ................................................................. 2-3
Basic ignition timing control........................................................ 2-4
Starting ignition timing control .................................................... 2-4
Acceleration ignition timing control............................................. 2-5
Cold and warm engine ignition timing control............................. 2-6
Engine speed control.................................................................. 2-7
Engine speed control during over-revving.................................. 2-7
Engine speed control during overheating................................... 2-7
Engine speed control during low oil pressure............................. 2-7
Power unit..................................................................................... 2-8
Outline ........................................................................................ 2-8
Balancer ..................................................................................... 2-9
Automatic decompression device (manual starter model) ......... 2-9
Lubrication system .................................................................. 2-10
System diagram ....................................................................... 2-10
Cooling system ......................................................................... 2-11
System diagram ....................................................................... 2-11
Intake and exhaust system.................................................... 2-12
System diagram ....................................................................... 2-12
Carburetor .................................................................................. 2-13
Prime Start system ................................................................... 2-13
Acceleration pump.................................................................... 2-14
PTT unit ....................................................................................... 2-15
Outline ...................................................................................... 2-15
Tilt up operation........................................................................ 2-16
Tilt down operation ................................................................... 2-17
Operation during malfunctions ................................................. 2-18
When the outboard motor hits something in the water............. 2-18