Yamaha Drag Star XVS650 Owner's Manual page 54

1. Spark plug wrench
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 dif-
ferent color, there could be something
wrong with the engine. Do not attempt
to diagnose such problems yourself.
Instead, take the motorcycle to a
Yamaha dealer. You should periodi-
PERIODIC MAINTENANCE AND MINOR REPAIR
cally remove and inspect the spark
plugs because heat and deposits will
cause any spark plug to slowly break
down and erode. If electrode erosion
becomes excessive, or if carbon and
other deposits are excessive, you
should replace the spark plug with the
specified plug.
Specified spark plug:
DPR7EA-9 (NGK)
X22EPR-U9 (DENSO)
6-8
a. Spark plug gap
Installation
1. Measure the electrode gap with a
wire thickness gauge and, if nec-
essary, adjust the gap to specifi-
cation.
Spark plug gap:
0.8 ~ 0.9 mm
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
2
3
4
5
6
7
8
9