BOMBARDIER SEA-DOO GS 5626 1998, Shop Manual

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Section 08 ELECTRICAL SYSTEM
Subsection 02 (IGNITION SYSTEM)
08-02-16
SPARK PLUGS
Disassembly
First unscrew the spark plug one turn.
Clean the spark plug and cylinder head with pres-
surize air then completely unscrew.
Heat Range
The proper heat range of the spark plugs is deter-
mined by the spark plugs ability to dissipate the
heat generated by combustion.
The longer the heat path between the electrode
tip to the plug shell, the hotter the spark plug op-
erating temperature will be — and inversely, the
shorter the heat path, the colder the operating
temperature will be.
A “cold” type plug has a relatively short insulator
nose and transfers heat very rapidly into the cylin-
der head.
Such a plug is used in heavy duty or continuous
high speed operation to avoid overheating.
The “hot” type plug has a longer insulator nose
and transfers heat more slowly away from its fir-
ing end. It runs hotter and burns off combustion
deposits which might tend to foul the plug during
prolonged idle or low speed operation.
1. Cold
2. Hot
A too “hot” plug will result in overheating and pre-
ignition, etc.
A too “cold” plug will result in fouling or may cre-
ate carbon build up which can heat up red-hot and
cause pre-ignition or detonation.
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: pro-
longed idling, or running on a too rich mixture due
to a faulty carburetor adjustment or incorrect fuel.
The plug face of a fouled spark plug has either a
dry coating of soot or an oily, glossy coating given
by an excess either of oil or of oil with soot. Such
coatings form a conductive connection between
the center electrode and ground.
Spark Plug Analysis
1. Overheated (light grey)
2. Normal (brownish)
3. Fouled (black)
The plug face (and piston dome) reveals the con-
dition of the engine, operating condition, method
of driving and fuel mixture. For this reason it is
advisable to inspect the spark plug at regular inter-
vals, examining the plug face (i.e. the part of the
plug projecting into the combustion chamber) and
the piston dome.
A00E09A
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CAUTION
Severe engine damage might occur if a
wrong heat range plug is used.
A00E0AA
1 2 3