Yamaha YBR250 2007 Service Manual page 319

TROUBLESHOOTING
The ignition system fails to operate
(no spark or intermittent spark).
Check:
1. Main and ignition fuses
2. Battery
3. Spark plug
4. Spark
5. Spark plug cap resistance
6. Ignition coil resistance
7. Crankshaft position sensor resistance
8. Main switch
9. Engine stop switch
10. Lean angle sensor
11. Wiring connections (of the entire ignition
system)
NOTE:
• Before troubleshooting, remove the following
part(s):
1. seat
2. side cowling (left)
3. fuel tank side covers (left and right)
4. fuel tank
• Troubleshoot with the following special tool(s).
Pocket tester
90890-03174
Spark dynamic tester
90890-06754
1. Main and ignition fuses
• Check the main and ignition fuses for
continuity.
Refer to "CHECKING THE FUSES" in
chapter 3.
• Are the main and ignition fuses OK?
YES NO
Replace the fuse(s).
IGNITION SYSTEM
2. Battery
• Check the condition of the battery.
Refer to "CHECKING AND CHARGING
THE BATTERY" in chapter 3.
Minimum open-circuit voltage
12.8 V or more at 20°C (68°F)
• Is the battery OK?
YES
3. Spark plugs
• Check the condition of the spark plug.
• Check the spark plug type.
• Measure the spark plug gap.
Refer to "CHECKING THE SPARK
PLUGS" in chapter 3.
Spark plug
DR8EA (NGK)
Spark plug gap
0.6~0.7 mm (0.024 ~ 0.028 in)
• Is the spark plug in good condition, is it of
the correct type, and is its gap within
specification?
YES
7-9
ELEC
NO
• Clean the battery
terminals.
• Recharge or
replace the battery.
NO
Re-gap or replace
the spark plug.