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PERIODIC MAINTENANCE
CHECKING AND CLEANING
THE SPARK PLUG
The spark plug is an important component
that can be checked relatively easily. As
the effectiveness of the spark plug gradu-
ally falls over time and according to how it
is used, periodic inspections involving re-
moval of the spark plug are required.
WARNING
9
The engine and muffler will still be
very hot immediately after the engine
is stopped. Exercise care not to burn
yourself.
9
When removing or installing the
spark plug, exercise care not to dam-
age its insulator. Poor electrical insu-
lation could cause high voltage leaks
resulting in a fire and serious burns.
1. Stop the engine and remove the engine
switch key.
2. Remove the spark plug cap.
1
2
1. Spark plug cap
2. Spark plug
3. Remove the spark plug using a spark
plug wrench.
1
2
1. Spark plug cap
2. Spark plug wrench
4. Check the spark plug for any signs of
burns.
Burn marks on spark plugs are usually
medium-to-light tan. If there are any
black or white burn marks, consult a
Yamaha dealer.
5. Remove deposits (carbon) from the
spark plug electrode using a plug clean-
er or a wire brush.
6. Check the spark plug number and spark
plug gap.
Spark plug number:
NGK BPR4ES
Spark plug gap:
0.7–0.8 mm (0.028–0.031 in)
1
2
3
1. Spark plug gap
2. Spark plug number
3. Insulator
7T0-28199-70-E0.indd 48
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