Operation Manual

PERIODIC MAINTENANCE AND MINOR REPAIR
6-8
6
2. Remove the spark plug as shown,
with the spark plug wrench includ-
ed in the owner’s tool kit.
To check the spark plugs
1. Check that the porcelain insulator
around the center electrode on
each spark plug is a medium-to-
light tan (the ideal color when the
motorcycle is ridden normally).
2. Check that all spark plugs installed
in the engine have the same color.
NOTE:
@
If any 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 motorcycle.
@
3. Check each spark plug for elec-
trode erosion and excessive car-
bon or other deposits, and replace
it if necessary.
To install a spark plug
1. Measure the spark plug gap with a
wire thickness gauge and, if nec-
essary, adjust the gap to specifica-
tion.
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 tight-
en it to the specified torque.
1. Spark plug wrench
Specified spark plug:
DPR7EA-9 (NGK) or
X22EPR-U9 (DENSO)
a. Spark plug gap
Spark plug gap:
0.8–0.9 mm
U5SCE0.book Page 8 Thursday, June 7, 2001 11:24 AM