Yamaha TT-R Owner's Manual page 48

PERIODIC MAINTENANCE AND MINOR REPAIR
1. Spark plug wrench
2. Remove the
shown, with the spark plug
wrench included in the owner's
tool kit.
6
To check the spark plug
1. Check that the porcelain insula-
tor around the center electrode
1
of the spark plug is a medium-to-
light tan (the ideal color when the
machine is ridden normally).
NOTE:
If the spark plug shows a distinctly
different color, the engine could be
defective. Do not attempt to diagnose
spark plug as
such
have a Yamaha dealer check the
machine.
2. Check the spark plug for elec-
trode erosion and excessive car-
bon
replace it if necessary.
Specified spark plug:
problems yourself. Instead,
or other deposits,
CR9E (NGK) or
U27ESR-N (DENSO)
6-7
a
a. Spark plug gap
To install the spark plug
1. Measure the spark plug gap with
a wire thickness gauge and, if
necessary, adjust the gap to
specification.
Spark plug gap:
0.7–0.8 mm (0.028–0.031 in)
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.