Yamaha YZ250F(S) Owner's Service Manual page 588

EC620000
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.
Spark gap test
Check entire ignition
system for connection.
(couplers, leads and
ignition coil)
Check engine stop switch.
Check ignition coil.
Check CDI magneto.
Check neutral switch.
Replace CDI unit.
*marked: Only when the ignition checker is used.
NOTE:
Remove the following parts before inspection.
G
1) Seat
2) Fuel tank
Use the following special tools in this inspection.
G
Dynamic spark tester:
YM-34487
Ignition checker:
90890-06754
No spark
OK
OK
Primary coil
Secondary coil
OK
Pickup coil
Charging coil
OK
OK
IGNITION SYSTEM
Spark
No good
No good
No good
No good
No good
No good
No good
Pocket tester:
YU-3112-C/90890-03112
6 - 3
– +
ELEC
*Clean or replace
spark plug.
Repair or replace.
Replace.
Replace.
Replace.
Replace.
Replace.
Repair or replace.