PERIODIC MAINTENANCE AND MINOR REPAIR
6-7
6
EAU19543
Checking the spark plugs
The spark plugs are important engine
components, which are easy to check.
Since heat and deposits will cause any
spark plug to slowly erode, the spark
plugs should be removed and checked
in accordance with the periodic mainte-
nance and lubrication chart. In addition,
the condition of the spark plugs can re-
veal the condition of the engine.
To remove a spark plug
1. Remove the spark plug cap.
2. Remove the spark plug as shown,
with the spark plug wrench includ-
ed in the owner’s tool kit.
To check the spark plugs
1. Check that the porcelain insulator
around the center electrode on
each spark plug is a medium-to-
light tan (the ideal color when the
vehicle is ridden normally).
2. Check that all spark plugs installed
in the engine have the same color.
NOTE:
If any spark plug shows a distinctly dif-
ferent color, the engine could be defec-
tive. Do not attempt to diagnose such
problems yourself. Instead, have a
Yamaha dealer check the vehicle.
3. Check each spark plug for elec-
trode erosion and excessive car-
bon or other deposits, and replace
it if necessary.
To install a spark plug
1. Measure the spark plug gap with a
wire thickness gauge and, if nec-
essary, adjust the gap to specifica-
tion.
1. Spark plug cap
1. Spark plug wrench
Specified spark plug:
NGK/DPR8EA-9
1. Spark plug gap
Spark plug gap:
0.8–0.9 mm (0.031–0.035 in)
U5WM22E0.book Page 7 Tuesday, August 10, 2004 9:26 AM
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