Spark Plug Analysis - TGB EST 1000 Service Manual

8-1. ELECTRIC SYSTEM
SPARK PLUG
Troubleshooting Fouled Spark Plug
Fouling of the spark plug is indicated by
irregular running of the engine, decreased
engine speed due to misfiring, reduced
performance, and increased fuel consumption.
This is due to a loss of compression. Other
possible cause are : prolonged idling or low
speed riding, a clogged air filter, incorrect fuel,
defective ignition system, 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

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.
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