
Section 08 ELECTRICAL SYSTEM
Sub-Section 02 (IGNITION SYSTEM)
08-02-16
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.
Spark Plug Installation
Prior to installation make sure that contact surfac-
es 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
Spark Plug Chart
NOTE : Refer to next page for Spark Plug
Symbol Explanation.
A00E0AA
123
Watercraft
models
Engine
Spark
plugs
Torque N•m
(lbf•ft)
Gap
mm (inch)
SP
SPI
GTS
587
NGK
BR8ES
24 (17)
0.5-0.6
(.020-.024)
SPX
GTI
HX
717
NGK
BR8ES
24 (17)
0.5-0.6
(.020-.024)
XP 787
NGK
BR8ES
24 (170
0.5-0.6
(.020-.024)
A00E0BA
2
1
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