Spark Plug Inspection - Yamaha WR400F Fahrer- Und Wartungshandbuch

ELECTRICAL/SPARK PLUG INSPECTION
EC370000
ELECTRICAL
EC371001

SPARK PLUG INSPECTION

1. Remove:
Spark plug
2. Inspect:
Electrode 1
Wear/damage → Replace.
Insulator color 2
Normal condition is a medium to light
tan color.
Distinctly different color → Check the
engine condition.
NOTE:
When the engine runs for many hours at low
speeds, the spark plug insulator will become
sooty, even if the engine and carburetor are in
good operating condition.
3. Measure:
Plug gap a
Use a wire gauge or thickness gauge.
Out of specification → Re-gap.
Spark plug gap:
0.7 ~ 0.8 mm (0.028 ~ 0.031 in)
Standard spark plug:
CR8E (NGK)
U24ESR-N (DENSO)
4. Clean the plug with a spark plug cleaner
if necessary.
5. Tighten:
Spark plug
NOTE:
Before installing a spark plug, clean the gas-
ket surface and plug surface.
Finger-tighten a the spark plug before torqu-
ing to specification b.
3 - 46
INSP
ADJ
13 Nm (1.3 m · kg, 9.4 ft · lb)