Checking The Spark Plug - Yamaha YFM50R Owner's Manual

EBU23211

Checking the spark plug

The spark plug is an important engine component,
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which is easy to check. Since heat and deposits
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will cause any spark plug to slowly erode, the spark
plug should be removed and checked in accor-
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dance with the periodic maintenance and lubrica-
tion chart. In addition, the condition of the spark
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plug can reveal the condition of the engine.
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To remove the spark plug
1. Remove the spark plug cap.
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1. Spark plug cap
2. Remove the spark plug as shown, with the
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1. Spark plug wrench
To check the spark plug
NOTE:
If the spark plug shows a distinctly different color,
the engine could be operating improperly. Do not
attempt to diagnose such problems yourself. In-
stead, have a Yamaha dealer check the ATV.
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spark plug wrench included in the owner's tool
kit.
1. Check that the porcelain insulator around the
center electrode of the spark plug is a medi-
um-to-light tan (the ideal color when the ATV
is ridden normally).
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