Yamaha 2004 YXR660 Service Manual page 359

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3. Spark plug
• Check the spark plug condition.
• Check the spark plug type.
• Check the spark plug gap.
Refer to "CHECKING THE SPARK PLUG"
in chapter 3.
Spark plug gap
0.8 ~ 0.9 mm (0.031 ~ 0.035 in)
4. Ignition spark gap
• Disconnect the spark plug cap from the
spark plug.
• Connect the pulse ignition spark checker
or ignition checker 1 as shown.
2 Spark plug cap
• Turn the main switch to "ON".
• Check the ignition spark gap a.
• Crank the engine by pushing the starter
switch, and increase the spark gap until a
misfiring occurs.
Minimum spark gap
6.0 mm (0.24 in)
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IGNITION SYSTEM
CORRECT
OUT OF
SPECIFICATION
OR NO SPARK
9 - 11
Standard spark plug
DPR8EA-9/NGK
INCORRECT
Repair or replace the spark plug.
MEETS SPECIFICATION
The ignition system is not faulty.
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ELEC