Yamaha 2004 YP400, Service Manual, Page: 97 / 417

3 - 18
CHK
ADJ
CHECKING THE SPARK PLUG
3. Remove:
• spark plug
CAUTION:
_
Before removing the spark plug, blow away
any dirt accumulated in the spark plug well
with compressed air to prevent it from fall-
ing into the cylinder.
4. Check:
• spark plug type
Incorrect
→
Change.
5. Check:
• electrode
1
Damage/wear
→
Replace the spark plug.
• insulator
2
Abnormal color
→
Replace the spark plug.
Normal color is medium-to-light tan.
6. Clean:
• spark plug
(with a spark plug cleaner or wire brush)
7. Measure:
• spark plug gap
a
(with a wire thickness gauge)
Out of specification
→
Regap.
8. Install:
• spark plug
NOTE:
_
Before installing the spark plug, clean the
spark plug and gasket surface.
9. Connect:
• spark plug cap
10.Install:
• storage box lower plate
Refer to “RIDER SEAT AND STORAGE
BOX”.
Spark plug type (manufacturer)
CR7E (NGK)
Spark plug gap
0.7 ~ 0.8 mm (0.028 ~ 0.031 in)
T
R
.
.
13 Nm (1.3 m · kg, 9.4 ft · lb)