2003 Yamaha Motorsports Road Star Midnight Owners Manual - Page 65

2003 Yamaha Motorsports Road Star Midnight Manual

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PERIODIC MAINTENANCE AND MINOR REPAIR The porcelain insulator around the center electrode of each spark plug should be a medium-to-light tan (the ideal color when the motorcycle is ridden 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. If a spark plug shows signs of electrode erosion and excessive carbon or other deposits, it should be replaced. Specified spark plug: DPR7EA-9/NGK or X22EPR-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. Spark plug gap: 0.03-0.04 in (0.8-0.9 mm) 6-8 Clean the surface of the spark plug gasket and its mating surface, and then wipe off any grime from the spark plug threads. Tightening torque: Spark plug: 12.5 ft·lbf (1.75 m·kgf, 17.5 Nm) NOTE: If a torque wrench is not available when installing a spark plug, a good estimate of the correct torque is 1/4-1/2 turn past finger tight. However, the spark plug should be tightened to the specified torque as soon as possible. @ @ a. Spark plug gap EAU01639 Checking the spark plugs The spark plugs are important engine components, which should be checked periodically, preferably by a Yamaha dealer. Since heat and deposits will cause any spark plug to slowly erode, they should be removed and checked in accordance with the periodic maintenance and lubrication chart. In addition, the condition of the spark plugs can reveal the condition of the engine. 6

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PERIODIC MAINTENANCE AND MINOR REPAIR
6-8
6
EAU01639
Checking the spark plugs
The spark plugs are important engine
components, which should be checked
periodically, preferably by a Yamaha
dealer. Since heat and deposits will
cause any spark plug to slowly erode,
they 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.
The porcelain insulator around the cen-
ter electrode of each spark plug should
be a medium-to-light tan (the ideal col-
or when the motorcycle is ridden nor-
mally), and all spark plugs installed in
the engine should have the same color.
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 motorcycle.
If a spark plug shows signs of electrode
erosion and excessive carbon or other
deposits, it should be replaced.
Before installing a spark plug, the spark
plug gap should be measured with a
wire thickness gauge and, if necessary,
adjusted to specification.
Clean the surface of the spark plug
gasket and its mating surface, and then
wipe off any grime from the spark plug
threads.
NOTE:
@
If a torque wrench is not available when
installing a spark plug, a good estimate
of the correct torque is 1/4–1/2 turn
past finger tight. However, the spark
plug should be tightened to the speci-
fied torque as soon as possible.
@
a.
Spark plug gap
Specified spark plug:
DPR7EA-9/NGK or
X22EPR-U9/DENSO
Spark plug gap:
0.03–0.04 in (0.8–0.9 mm)
Tightening torque:
Spark plug:
12.5 ft·lbf (1.75 m·kgf, 17.5 Nm)