PERIODIC MAINTENANCE AND MINOR REPAIR
6-8
6
Inspection
The spark plug is an important engine
component and is easy to inspect. The
condition of the spark plug can indicate
the condition of the engine. Normally,
all spark plugs from the same engine
should have the same color on the
white insulator around the center elec-
trode. The ideal color at this point is a
medium-to-light tan color for a motor-
cycle that is being ridden normally. If
one spark plug shows a distinctly differ-
ent color, there could be something
wrong with the engine.
Do not attempt to diagnose such prob-
lems yourself. Instead, take the motor-
cycle to a Yamaha dealer. You should
periodically remove and inspect the
spark plugs because heat and deposits
will cause any spark plug to slowly
break down and erode. If electrode ero-
sion becomes excessive, or if carbon
and other deposits are excessive, you
should replace the spark plug with the
specified plug.
Installation
1. Measure the electrode gap with a
wire thickness gauge and, if nec-
essary, adjust the gap to specifica-
tion.
2. Clean the gasket surface. Wipe off
any grime from the threads.
3. Install the spark plug and tighten it
to the specified torque.
1. Spark plug wrench
Specified spark plug:
DPR7EA-9 (NGK) or
X22EPR-U9 (DENSO)
a. Spark plug gap
Spark plug gap:
0.8 ~ 0.9 mm
E_4xs_Periodic.fm Page 8 Tuesday, November 30, 1999 2:36 PM
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