Checking The Spark Plugs - Yamaha YZFR3AN 2021 Owner's Manual

Periodic maintenance and adjustment

Checking the spark plugs

The spark plugs are important engine
components, which
checked periodically, preferably by a
Yamaha dealer. Since heat and depos-
its will cause any spark plug to slowly
erode, they should be removed and
checked in accordance with the peri-
odic maintenance and lubrication
chart. In addition, the condition of the
spark plugs can reveal the condition of
the engine.
The porcelain insulator around the
7
center 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 engine should have the same
color. If any spark plug shows a dis-
tinctly different color, the engine could
be operating improperly. Do not at-
tempt to diagnose such problems
yourself. Instead, have a Yamaha deal-
er check the vehicle.
If a spark plug shows signs of elec-
trode erosion and excessive carbon or
other deposits, it should be replaced.
EAU19643
Specified spark plug:
NGK/CR8E
should be
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.
Tightening torque:
Spark plug:
13 N·m (1.3 kgf·m, 9.6 lb·ft)
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.
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