Aprilia Consumer Service Spa
Technical Service and Training
Release 4 july 99
This material is didactic and
may be changed following the technical
development of the product
SECTION 2: IGNITION SYSTEM
The ignition system is controlled by the control unit. The system is a normal one, known as a
digital transistorised ignition system, which sets the correct timing on the basis of the engine
rpm and throttle position. It is made up of the crankshaft sensor (pick up coil), control unit, two
ignition coils and spark plugs.
1. The ignition coil power supply is governed by the side stand safety circuit and by the gear
position.
2.
The timing is constantly controlled by the throttle position and the rpm
The devices described below affect the timing in the stopping or starting of the ignition
system.
Crankshaft sensor:
The engine pick up coil produces a signal when it meets the projecting part of the
magneto flywheel.
The wave generated is sent to the control unit which calculates the engine rpm; this
signal determines the timing.
Throttle position sensor:
This sensor, mounted on the throttle body, has a variable resistance which changes the
opening value of the throttle. On the basis of this signal, the control unit sets the timing in
response to the engine rpm.
The timing mapping is made up of two factors: the throttle position and the engine rpm.
The ignition is inductive and not the capacitive discharge type. ! NEVER SHORT CIRCUIT TO
GROUND THE L.T. LEADS TO THE COILS
WAVE
FORM
ARRANGE
CIRCUIT
CPU
VIBRATOR
ROM
THROTTLE
POSITION
TEMP.
SENSOR
GEAR
SWITCH
POSITIVO
MAPPING