Ski-Doo Ski Doo SUMMIT 2005 [1295/1429] Disassembly

Ski-Doo Ski Doo SUMMIT 2005 [1295/1429] Disassembly
Section 08 ELECTRICAL
Subsection 02 (SPARK PLUGS)
DISASSEMBLY
First unscrew the spark plug 1 turn.
Clean the spark plug and cylinder head with pres-
surized air, then completely unscrew.
WARNING
Whenever using compressed air, always
wear protective eye wear.
HEAT RANGE
The proper operating temperature or heat range
of the spark plugs is determined by the spark plug
ability to dissipate the heat generated by combus-
tion.
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 firing
end. It runs hotter and burns off combustion de-
posits which might tend to foul the plug during
prolonged idle or low speed operation.
A00E09A
12
1. Cold
2. Hot
CAUTION: Severe engine damage might occur
if a wrong heat range plug is used.
A too hot plug will result in overheating and pre-
ignition, etc.
A too cold plug will result in fouling (shorting the
spark plug) or may create carbon build up which
can heat up red-hot and cause pre-ignition or det-
onation.
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 fu-
el and/or fuel mixing. 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 con-
ductive connection between the center electrode
and ground.
SPARK PLUG ANALYSIS
A00E0AA
123
1. Overheated (light grey)
2. Normal (brownish)
3. Fouled (black)
Theplugelectrodeandpistondomerevealthe
condition of the engine, operating condition,
method of driving and fuel mixture. For this rea-
son it is advisable to inspect the spark plug at
regular intervals, examining the plug electrode
and the piston dome.
mmr2005-043 435

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