Yamaha YZ250 User Manual

6-2
IGNITION SYSTEM
ELEC
EC620000
IGNITION SYSTEM
EC621003
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.
*Clean or replace
spark plug.
Primary coil
Secondary coil
Repair or replace.
Spark
Check entire ignition
system for connection.
Spark gap test
No good
No good
No good
No good
No good
No good
No Spark
Check “ENGINE STOP”
button.
Pick-up coil
Source coil
Check ignition coil.
Check CDI magneto.
Replace CDI unit.
Replace.
Replace.
Replace.
Replace.
Replace.
*marked: Only when the ignition checker is used.
NOTE:
9
Remove the following parts before inspection.
1) Seat
2) Fuel tank
9
Use the following special tools in this inspection.
Dynamic spark tester:
YM-34487
Ignition checker:
90890-06754
Pocket tester:
YU-3112-C/90890-03112
OK
OK
OK
OK
Replace.
Check spark plug cap.
No good
OK
1P8-9-30-6 21/5/04 11:42 AM Page 4

Yamaha YZ250 Specifications

General

Engine Type	249cc liquid-cooled 2-stroke; reed-valve inducted
Bore x Stroke	66.4mm x 72.0mm
Compression Ratio	8.9~10.6:1
Ignition	CDI
Transmission	5-speed; multiplate wet clutch
Final Drive	Chain
Suspension Rear	KYB® single shock; fully adjustable, 12.4-in travel
Brakes Front	Hydraulic disc, 270mm
Brakes Rear	Hydraulic disc, 240mm
Tires Front	80/100-21
Tires Rear	110/90-19
Length	85.8 in
Width	32.5 in
Wheelbase	58.5 in
Ground Clearance	14.2 in
Fuel Capacity	2.1 gal
Wet Weight	227 lb
Suspension Front	KYB® inverted fork; fully adjustable, 11.8-in travel
Fuel Delivery	Keihin PWK38S carburetor