Perio
d
ic maintenance an
d
a
d
justment
7-8
7
EAU19623
Checkin
g
the spark plu
g
The spark plug is an important engine
component, which should be checked
periodically, preferably by a Yamaha
dealer. Since heat and deposits will
cause any spark plug to slowly erode,
it should be removed and checked in
accordance with the periodic mainte-
nance and lubrication chart. In addi-
tion, 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 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 deal-
er check the vehicle.
If the spark plug shows signs of elec-
trode erosion and excessive carbon or
other deposits, it should be replaced.
Before installing a spark plug, the
spark plug gap should be measured
with a wire thickness gauge and, if
necessary, adjusted to specification.
Clean the surface of the spark plug
gasket and its mating surface, and
then wipe off any grime from the spark
plug threads.
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.
Specifie
d
spark plu
g
:
NGK/LMAR8A-9
1. Spark plug gap
Spark plu
g
g
ap:
0.8–0.9 mm (0.031–0.035 in)
Ti
g
htenin
g
torque:
Spark plug:
13 N·m (1.3 kgf·m, 9.4 lb·ft)
UB74E0E0.book Page 8 Tuesday, May 2, 2017 1:04 PM
