Buell P3, Service Manual, Page: 90 / 440

2007 Buell P3: Maintenance 1-31
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SPARK PLUG 1.16
GENERAL
Change spark plug at every 10,000 mile (16,000 km) service
interval. Use only Harley-Davidson No. 10R12A plug as a
replacement.
INSPECTION
1. Disconnect cable from both spark plug by pulling on rub-
ber boot (not cable).
2. Remove spark plug and examine.
3. See Figure 1-35. 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 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 indicates a carbu-
retor air-fuel mixture that is too rich, engine idling for
excessive periods of time and/or enrichener usage
for excessive periods of time.
c. A light brown, glassy deposit indicates an over-
heated plug. This condition may be accompanied by
cracks in the insulator or by erosion of the elec-
trodes 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 pow-
dery deposit indicates balanced combustion. Clean
off spark plug deposits at regular intervals.
4. If the plug requires cleaning between tune-ups and
replacement plug is not available, proceed as follows:
a. De-grease firing end of spark plug using ELECTRI-
CAL CONTACT CLEANER. Dry plug with com-
pressed air.
b. Use a thin file to flatten spark plug electrode. A
spark plug with sharp edges on its electrodes
requires 25%-40% less firing voltage than one with
rounded edges.
5. If the plug cannot be cleaned, replace with HD No.
10R12A spark plug.
6. Check electrode gap with a wire-type feeler gauge. Gap
should be 0.035 in. (0.9 mm).
7. Apply Loctite Anti-Seize to threads of spark plug. Install
and tighten to 12-18 ft-lbs (16-24.4 Nm).
8. Connect spark plug cable. Verify that cable is securely
connected to ignition coil and spark plug.
Figure 1-35. Typical Spark Plug Deposits
4636a