Yamaha Vmax VMX12N Owner's Manual page 45

1. Spark plug wrench
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.
PERIODIC MAINTENANCE AND MINOR REPAIR
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
it if necessary.
Specified spark plug:
DPR8EA-9/NGK or
X24EPR-U9/DENSO
6 - 1 0
replace
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.
Spark plug gap:
0.8-0.9 mm (0.03-0.04 in)
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.