Yamaha F225F Service Manual page 64

TECH
FEA
Basic ignition timing
The basic ignition timing is divided into 3 types: engine starting ignition timing, idling basic ignition
timing, and normal basic ignition timing.
Basic ignition timing
Engine starting ignition timing
(BTDC 10°)
Idling basic ignition timing
Normal basic ignition timing
Ignition timing restriction
The advancing or retarding of the ignition timing is restricted according to the engine speed, engine
temperature, and dashpot function.
Restriction
Engine speed restriction
Engine temperature restriction
Dashpot function restriction
(when the throttle valve is
closed quickly)
Ignition timing compensation
The ignition timing control makes advance or retard compensations to the ignition timing according
to the engine operating conditions. The compensations are determined according to the signals
from the following sensors.
Compensation
After start-up
For stable idle speed
During dashpot function operation
For shift-cutout control
During acceleration
2-9
Technical features and description
Engine is starting (less than
500 r/min)
Engine speed is at engine idle
speed
Engine speed is more than
engine idle speed
Corresponding sensor
Pulser coil
Engine temperature sensor
Pulser coil and LPS
Criteria
Corresponding sensor
Engine temperature sensor
LPS and pulser coil
LPS, SPS, and pulser coil
Pulser coil and SPS
Air pressure sensor and TPS
Ignition cylinder
All cylinders simultaneously
Each cylinder sequentially
Each cylinder sequentially
Details
The ignition timing is restricted
between BTDC 50° (advance
angle) and ATDC 20° (retard
angle) according to the engine
speed.
The ignition timing is restricted
between BTDC 50° (advance
angle) and ATDC 30° (retard
angle) according to the engine
temperature.
The ignition timing is restricted
to ATDC 20° when the
dashpot function operates.