Yamaha TW125 Owner's Manual page 39

PERIODIC MAINTENANCE AND MINOR REPAIR
To check the spark plug
1. Check that the porcelain insula-
tor around the center electrode
of the spark plug is a medium-to-
light tan (the ideal color when the
motorcycle is ridden normally).
NOTE:
If the spark plug shows a distinctly
different color, the engine could be
defective. Do not attempt to diagnose
such problems yourself.
have a Yamaha dealer check the
motorcycle.
6
2. Check the spark plug for elec-
trode erosion and excessive car-
bon or other
replace it if necessary.
Specified spark plug:
DR8EA (NGK)
a. Spark plug gap
To install the spark plug
Instead,
1. Measure the spark plug gap with
a wire thickness gauge and, if
necessary, adjust the gap to
specification.
Spark plug gap:
0.6–0.7 mm
deposits, and
2. Clean the surface of the spark
plug gasket and its mating sur-
face, 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.
a
6-8
Tightening torque:
Spark plug:
17.5 Nm (1.75 m·kgf)
NOTE:
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 pos-
sible.
4. Install the spark plug cap.