Spark Plug Inspection - Yamaha DT501988 Owner's Manual

H-203
Spark plug inspection
The spark plug is an important engine com-
ponent and is easy to inspect. The condition
of the spark plug can indicate something of
the condition of the engine. The ideal color
on the white porcelain insulator around the
center electrode is a medium to light tan colol
for a motorcycle that is being ridden normally.
Do not attempt to diagnose any problems
yourself. Instead, take the motorcycle to a
Yamaha dealer. You should periodically re-
move and inspect the spark plug because heat
and deposits will cause the spark plug to
slowly break down and erode. If electrode
erosion becomes excessive, or if carbon and
other deposits are excessive, you should re-
place the spark plug with a proper type plug.
Standard spark plug:
BRSES (NGK)
7-15
1. Spark plug gap
Before installing the spark plug, measure the
electrode gap with a wire thickness gauge;
adjust the gap to specification as necessary.
Spark plug gap:
0.7 - 0.8 mm (0.028 - 0.031 in)
When installing the plug, always clean the
gasket surface and use a new gasket. Wipe
off any grime from the threads, and torque.
the spark plug properly.