Spark Plugs; Inspection - Buell XB 2010 Service Manual

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SPARK PLUGS

INSPECTION

Check spark plugs:
Replace every 10,000 mile (16,000 km) service interval.
Use only Harley-Davidson 10R12X spark plugs.
1. Remove left side air scoop to access front cylinder spark
plug. See 2.49 AIR SCOOPS.
2. Disconnect cable from front spark plug.
3. Using a 5/8 in. box end wrench and 5/8 in. spark plug
socket, remove front spark plug.
4. Remove seat.
5. Remove intake cover and air cleaner assembly. See
2.38 INTAKE COVER and
6. Disconnect cable from rear spark plug (use automotive
spark plug boot remover/installer if required).
7. Using a 5/8 in. wobble socket and 12 in. extension, remove
rear spark plug.
8. See Figure 1-42. Compare your observations of the plug
deposits with the descriptions provided below.
a. A wet, black and shiny deposit on plug base, elec-
trodes and ceramic insulator tip (1) indicates an oil
fouled plug. The condition may be caused by one or
more of the following: worn pistons, worn piston rings,
worn valves, worn valve guides, worn valve seals, a
weak battery or a faulty ignition system.
b. A dry, fluffy or sooty black deposit (2) indicates an
air-fuel mixture that is too rich and/or engine idling for
excessive periods.
c. A light brown, glassy deposit (3) indicates an over-
heated plug. This condition may be accompanied by
cracks in the insulator or by erosion of the electrodes
and is caused by an air-fuel mixture that is too lean,
a hot-running engine, valves not seating or improper
ignition timing. The glassy deposit on the spark plug
is a conductor when hot and may cause high-speed
misfiring. A plug with eroded electrodes, heavy
deposits or a cracked insulator must be replaced.
d. A plug with a white, yellow, tan or rusty brown
powdery deposit (4) indicates balanced combustion.
Clean off spark plug deposits at regular intervals.
4.3 AIR CLEANER ASSEMBLY.
sm00099
1
3
1. Oil-fouled
2. Sooty black deposits
3. Overheated
4. Balanced combustion
Figure 1-42. Typical Spark Plug Deposits
Compressed air can pierce the skin and flying debris from
compressed air could cause serious eye injury. Wear
safety glasses when working with compressed air. Never
use your hand to check for air leaks or to determine air
flow rates. (00061a)
9. If the plugs require cleaning between tune-ups and
replacement plugs are not available, proceed as follows:
a. Degrease firing end of spark plug using ELECTRICAL
CONTACT CLEANER. Dry plug with compressed air.
b. Use a thin file to flatten spark plug electrodes. A spark
plug with sharp edges on its electrodes requires 25-
40% less firing voltage than one with rounded edges.
10. If the plugs cannot be cleaned, replace with 10R12X spark
plugs.
11. Check electrode gap with a wire-type feeler gauge. Gap
should be 0.035 in. (0.9 mm).
NOTES
Start threading rear spark plug with 3/8 in. fuel hose, being
careful not to cross thread spark plug.
Start front spark plug with fingers.
2010 XB Service: Maintenance 1-37
1.15
2
4