Polaris Trail Boss 330 Quadricycle - Manual (Page 93)

91
MAINTENANCE AND LUBRICATION
Spark Plugs
Spark Plug Condition
Normal
The insulator tip is tan or brown. There are few combustion deposits.
The electrodes are not burned or eroded. This indicates the proper type
and heat range for the engine and the service.
NOTE: The tip should not be white. A white insulator tip indicates
overheating, caused by use of an improper spark plug or
incorrect carburetion adjustments.
Fouled
The insulator tip is black. A damp film covers the firing end. There
may be a carbon layer over the entire nose. Generally, the electrodes
are not worn. General causes of fouling are excessive oil consumption,
improper use of the choke, or incorrect carburetion adjustments.