Yamaha F50A Service Manual page 23

Pulser coil
The pulser coil transmits the pulser signals, which are generated in the pulser coil in accordance
with the rotation of the flywheel, to the CDI unit. Among the two protrusions that are provided for
generating signals, one is used for cylinders #1 and #4, and the other for cylinders #2 and #3, thus
enabling the pulser coil to simultaneously ignite two cylinders.
To provide ignition signals to the cylinders, the microcomputer determines the ignition cylinder and
ignition timing. These are based on the cylinder identification signals generated by the protrusion for
identifying cylinders, and on the pulser signals generated by the protrusions for generating ignition
signals.
1 Flywheel
2 Rotating direction
3 Protrusion for cylinders #1 and #4
4 Pulser coil
5 Cylinder identification protrusion
6 Protrusion for cylinders #2 and #3
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