BOMBARDIER DS 650, Shop Manual

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Section 05 ELECTRICAL
Subsection 05 (IGNITION SYSTEM)
VMR2004_021_05_05A.FM
05-05-5
SPARK PLUG
DISASSEMBLY
Unplug the spark plug cable
Unscrew the spark plug one turn.
Clean the spark plug and cylinder head with pres-
surized air then completely unscrew.
FOULING
Fouling of the spark plug is indicated by irregular
running of the engine, decreased engine speed
due to misfiring, reduced performance, and in-
creased fuel consumption. This is due to a loss of
compression. Other possible causes are: prolonged
idling or low-speed riding, or running on a too rich
mixture due to abuse of choke, a clogged air filter,
a faulty carburetor adjustment, incorrect fuel, de-
fective ignition system, incorrect ignition timing,
incorrect spark plug gap, lubricating oil entering
the combustion chamber, or too cold spark plug.
The plug face of a fouled spark plug has either a
wet black deposit or a black carbon fouling. Such
coatings form a conductive connection between
the center electrode and ground.
SPARK PLUG ANALYSIS
TYPICAL
1. Overheated (light grey, white)
2. Normal (light brown, brown)
3. Fouled (black, wet or dry, dark deposits, grey, melted coating)
The plug face reveals the condition of the engine,
operating condition, method of driving and fuel
mixture. For this reason it is advisable to inspect
the spark plug at regular intervals, examining the
plug face (i.e. the part of the plug projecting into
the combustion chamber).
SPARK PLUG INSTALLATION
CAUTION: Always use the recommended
spark plug.
Prior to installation make sure that contact surfaces
of the cylinder head and spark plug are free of
grime.
1. Using a wire feeler gauge, set electrode gap ac-
cording to the following chart.
2. Apply anti-seize lubricant over the spark plug
threads to prevent possible seizure.
3. Hand screw spark plug into cylinder head and
tighten with a torque wrench and a proper socket.
1. Proper socket
2. Improper socket
4. Torque spark plug to 20 N•m (15 lbf•ft).
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