Yamaha YZ450F(Y), Owner'S Manual

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6-3
IGNITION SYSTEM
IGNITION SYSTEM
INSPECTION STEPS
Use the following steps for checking the possibility of the malfunctioning engine being attributable to ignition system failure
and for checking the spark plug which will not spark.
*marked: Only when the ignition checker is used.
• Remove the following parts before inspection.
1. Seat
2. Fuel tank
• Use the following special tools in this inspection.
Spark gap test Spark → *Clean or replace spark plug.
No spark ↓
Check entire ignition system for connection.
(couplers, leads and ignition coil) No good → Repair or replace.
OK ↓
Check engine stop switch. No good → Replace.
OK ↓
Check ignition coil. (primary coil and secondary
coil) No good →
Replace.
OK ↓
Check CDI magneto. (pickup coil and charging
coil) No good → Replace.
OK ↓ Check neutral switch. No good
→
Repair or replace.
OK ↓
Replace CDI unit.
Dynamic spark tester: YM-34487
Ignition checker:
90890-06754 Pocket tester:
YU-3112-C/90890-03112