Map-Controlled Cdi Unit - Yamaha WR250F Fahrer- Und Wartungshandbuch

MAP-CONTROLLED CDI UNIT

A map-controlled, CDI ignition system is used in the WR250F.
The microcomputer in the CDI unit detects the engine speed and throttle position, thus determining the optimum ignition
timing through the entire operating range. In this way, quick throttle response can be achieved according to various riding
conditions.
Throttle position sensor
I I I I Function of Component
Component
Throttle position sensor
Pickup coil
CDI unit
I I I I Principal of 3-Dimensional Control
Conventionally, ignition timing was controlled only by
engine revolutions (2-dimensional control).
However, ignition timing needs advancement also by
engine load. Thus, accurate ignition timing can be deter-
mined by adding throttle opening to determine ignition
timing (3-dimensional control).
MAP-CONTROLLED CDI UNIT
CDI unit
Detects throttle valve opening and inputs it into the computer in the CDI unit as a
throttle opening signal.
Detects signal rotor revolutions and inputs them into the computer in the CDI unit as
engine revolution signals.
The signals of the throttle position sensor and pickup coil sensor are analyzed by
the computer in the CDI unit, which then adjusts ignition timing for the operation
requirements.
6 - 3
ELEC
Ignition coil
AC magneto rotor
Pickup coil
Function
3-D Image Map of Ignition Timing
(different from actual characteristics)
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