Yamaha F200B, Service Manual

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2-7
TECH
FEA
Technical features and description
Knock control
In knock control, the engine ECM receives the knock signal from the knock sensor, which is
installed on the cylinder block between the cylinder banks. The engine ECM retards the ignition tim-
ing and decreases the engine speed according to the amount of knocking to protect the engine from
damage.
If the knocking occurs frequently, the ignition timing is retarded until the knocking is no longer
detected, and the retarded ignition timing is maintained.
Also, a learning function for the knock control has been adopted.
The knock control activates according to the following conditions:
The knock control also activates when the engine temperature sensor is malfunctioning regardless
of the preceding conditions.
Engine
temperature
Engine speed
Less than 20 °C
(68 °F)
20–25 °C (68–77 °F)
More than 25 °C
(77 °F)
Less than 4500 r/min Knock control does
not activate Knock control
activates if conditions
continue for 0.5
second Knock control
activates
4500 r/min or more Knock control
activates