Checking The Spark Plugs - Yamaha TDM900 Owner's Manual

PERIODIC MAINTENANCE AND MINOR REPAIR

Checking the spark plugs

Spar k pl u gs, checki n g
The spark plugs are important engine
components, which
checked periodically, preferably by a
Yamaha dealer. Since heat and
deposits will cause any spark plug to
slowly erode, they
removed and checked in accordance
with the periodic maintenance and
lubrication chart. In addition, the con-
dition of the spark plugs can reveal
the condition of the engine.
The porcelain insulator around the
6
center electrode of each spark plug
should be a medium-to-light tan (the
ideal color when the motorcycle is rid-
den normally), and all spark plugs
installed in the engine should have
the same color. If any spark plug
shows a distinctly different color, the
engine could be defective. Do not
attempt to diagnose such problems
yourself. Instead, have a Yamaha
dealer check the motorcycle.
EAU01880
If a spark plug shows signs of elec-
trode erosion and excessive carbon
or other deposits, it should be
should be
replaced.
Specified spark plug:
DPR8EA-9 (NGK) or
should be
X24EPR-U9 (DENSO)
Before installing a spark plug, the
spark plug gap should be measured
with a wire thickness gauge and, if
necessary, adjusted to specification.
a. Spark plug gap
Clean the surface of the spark plug
gasket and its mating surface, and
then wipe off any grime from the
spark plug threads.
6-7
Spark plug gap:
0.8–0.9 mm
Tightening torque:
Spark plug:
17.5 Nm (1.75 m·kgf)