Yamaha YJ125T - Manual (Page 41)

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PERIODIC MAINTENANCE AND MINOR REPAIR
EAUT1170
Checking the spark plug
1
ZAUM00**
1. Spark plug cap
The spark plug is an important engine
component, which is easy to check.
Since heat and deposits will cause any
spark plug to slowly erode, the spark
plug should be removed and checked in
accordance with the periodic mainte-
nance and lubrication chart. In addition,
the condition of the spark plug can re-
veal the condition of the engine.
To remove the spark plug
1. Remove panel A. (See page 6-6.)
2. Remove the spark plug cap.
3. Remove the spark plug as shown,
with the spark plug wrench included
in the owner’s tool kit.
To check the spark plug
1. Check that the porcelain insulator
around the center electrode of the
spark plug is a medium-to-light tan
(the ideal color when the vehicle is
ridden normally).
NOTE:
If the spark plug shows a distinctly dif-
ferent color, the engine could be defec-
tive. Do not attempt to diagnose such
problems yourself. Instead, have a
Yamaha dealer check the vehicle.
2. Check the spark plug for electrode
erosion and excessive carbon or
other deposits, and replace it if nec-
essary.
Specified spark plug:
CR7E (NGK)
To install the spark plug
1. Measure the spark plug gap with a
wire thickness gauge and, if nec-
essary, adjust the gap to specifi-
cation.
1
ZAUM0037
1. Spark plug gap
Spark plug gap:
0.7~0.8 mm (0.028~0.032 in)
2. Clean the surface of the spark plug
gasket and its mating surface, and
then wipe off any grime from the
spark plug threads.
3. Install the spark plug with the spark
plug wrench, and then tighten it to
the specified torque.
Tightening torque:
Spark plug:
13 Nm (1.3m • kgf, 9.4ft • lbf)
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