Checking The Spark Plug - Yamaha AEROX YQ50 Owner's Manual

PERIODIC MAINTENANCE AND ADJUSTMENT

Checking the spark plug

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 ac-
cordance with the periodic mainte-
nance and lubrication chart. In addition,
the condition of the spark plug can re-
veal the condition of the engine.
The porcelain insulator around the cen-
ter electrode of the spark plug should
be a medium-to-light tan (the ideal color
when the vehicle is ridden normally). If
6
the spark plug shows a distinctly differ-
ent color, the engine could be operating
improperly. Do not attempt to diagnose
such problems yourself. Instead, have
a Yamaha dealer check the vehicle.
If the spark plug shows signs of elec-
trode erosion and excessive carbon or
other deposits, it should be replaced.
Specified spark plug:
NGK/BR8HS
EAU19622 Before installing a spark plug, the spark
plug gap should be measured with a
wire thickness gauge and, if necessary,
adjusted to specification.
1
ZAUM0037
1. Spark plug gap
Spark plug gap:
0.6–0.7 mm (0.024–0.028 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:
20 Nm (2.0 m·kgf, 14 ft·lbf)
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 speci-
fied torque as soon as possible.
6-7