Yamaha XZ10YMXH Owner's Manual page 167

The porcelain insulator around the center
electrode of each spark plug should be a me-
dium-to-light tan color (the ideal color when
the vehicle is ridden normally), and all spark
plugs installed in the engine should have a
similar color. If any spark plug shows a dis-
tinctly different color, the engine could be op-
erating improperly. Do not attempt to
diagnose such problems yourself. Instead,
have a Yamaha dealer check the vehicle.
If a spark plug shows signs of electrode ero-
sion and excessive carbon or other deposits,
it should be replaced.
Specified spark plug:
NGK/CR9EB
Before installing a spark plug, the spark plug
gap should be measured with a wire thick-
ness gauge and, if necessary, adjusted to
specification.
1
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, 9.4 lb·ft)
8-36
8