Checking The Spark Plug - Yamaha ZUMA 125 Owner's Manual

Periodic maintenance and adjustment

Checking the spark plug

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. Place the vehicle on the center-
stand.
2. Remove panel B. (See page 7-7.)
3. Remove the spark plug cap.
1. Spark plug cap
4. Remove the spark plug as shown,
with the spark plug wrench includ-
ed in the tool kit.
1
1. Spark plug wrench
To check the spark plug
EAUT1838
1. Check that the porcelain insulator
TIP
If the spark plug shows a distinctly dif-
ferent color, the engine could be oper-
ating improperly. Do not attempt to
diagnose such problems yourself. In-
stead, have a Yamaha dealer check
the vehicle.
2. Check the spark plug for electrode
Specified spark plug:
1
3. Measure the spark plug gap with a
1. Spark plug gap
Spark plug gap:
To install the spark plug
1. Clean the surface of the spark plug
7-8
around the center electrode of the
spark plug is a medium-to-light tan
(the ideal color when the vehicle is
ridden normally).
erosion and excessive carbon or
other deposits, and replace it if
necessary.
DENSO / U22ESR-N
wire thickness gauge and, if nec-
essary, adjust the gap to specifica-
tion.
1
0.7–0.8 mm (0.028–0.031 in)
gasket and its mating surface, and
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