Yamaha YZ450F, Owner'S Service Manual

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INSP
ADJ
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
→
Regap.
Spark plug gap:
0.7 ~ 0.8 mm (0.028 ~ 0.031 in)
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
.
T
R
.
.
13 Nm (1.3 m · kg, 9.4 ft · lb)