Checking The Spark Plugs - Yamaha FJR13AX(C) Owner's Manual

To install the panel
1. Place the panel in the original posi-
tion, and then install the bolts and
the quick fastener screws.
1. Panel E
1. Panel F
2. Install the seats.
PERIODIC MAINTENANCE AND MINOR REPAIR

Checking the spark plugs

The spark plugs are important engine
components, which should be checked
periodically, preferably by a Yamaha
dealer. Since heat and deposits will
cause any spark plug to slowly erode,
they should be removed and checked
in accordance with the periodic mainte-
nance and lubrication chart. In addition,
the condition of the spark plugs can re-
veal the condition of the engine.
The porcelain insulator around the cen-
ter electrode of each spark plug should
be a medium-to-light tan (the ideal color
when the vehicle is ridden normally),
and all spark plugs installed in the en-
gine should have the same color. If any
spark plug shows a distinctly different
color, the engine could be operating im-
properly. Do not attempt to diagnose
such problems yourself. Instead, have
a Yamaha dealer check the vehicle.
If a spark plug shows signs of electrode
erosion and excessive carbon or other
deposits, it should be replaced.
6-11
EAU19642
Specified spark plug:
NGK/CR8E
DENSO/U24ESR-N
Before installing a spark plug, the spark
plug gap should be measured with a
wire thickness gauge and, if necessary,
adjusted to specification.
1. Spark plug gap
Spark plug gap:
0.7–0.8 mm (0.028–0.031 in)
Clean the surface of the spark plug
gasket and its mating surface, and then
wipe off any grime from the spark plug
threads.
6