Checking The Spark Plug - Yamaha TT-R125Y Owner's Manual

PERIODIC MAINTENANCE AND ADJUSTMENT

Checking the spark plug

The spark plug is an important engine
component, which should be checked
periodically, preferably by a Yamaha
dealer. Since heat and deposits will cau-
se any spark plug to slowly erode, it
should be removed and checked in
accordance with
maintenance and lubrication chart. In
addition, the condition of the spark plug
can reveal the condition of the engine.
The porcelain insulator around the center
electrode of the spark plug should be a
medium-to-light tan (the ideal color when
the vehicle is ridden normally). If the
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spark plug shows a distinctly different
color, the engine could be operating
improperly. Do not attempt to diagnose
such problems yourself. Instead, have
a Yamaha dealer check the vehicle.
If the spark plug shows signs of
electrode erosion and excessive carbon
or other deposits, it should be replaced.
Specified spark plug:
CR7HSA (NGK)
U22FSR-U (DENSO)
EAU19622
the periodic
1. Spark plug gap
Before installing a spark plug, the spark
plug gap should be measured with a wire
thickness gauge and, if necessary,
adjusted to specification.
Spark plug gap:
0.6-0.7 mm (0.024-0.028 in)
Clean the surface of the spark plug
gasket and its mating surface, and then
wipe off any grime from the spark plug
threads.
Tightening torque:
Spark plug:
13 Nm (1.3 m.kgf, 9.4 ft.lbf)
TIP
If a torque wrench is not available when
installing a spark plug, a good estimate
of the correct torque is 1/4 -1/2 turn past
finger tight. However, the spark plug
should be tightened to the specified
torque as soon as possible.
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