Commonly Located: The ignition coil is generally located on the upper portion of the frame, near the top of the engine. It can commonly be found above the radiator.
Physical Description: The ignition coil is normally a squarish shape with one to three smaller wires leading into the wiring harness and one larger wire leading to the spark plug. While some ignition coils have a removable spark plug wire, most do not. The wire leading to the spark plug is covered by a thick rubber boot. The spark plug wire boot is usually a separate piece that can be replaced independent of the ignition coil.
Function: When the engine is at top dead center, the pickup coil signals the ignition coil to send a high voltage pulse to the spark plug. The spark plug wire boot ensures that none of this energy escapes on it's way to the spark plug. This high voltage pulse is what causes the spark that ignites the air and fuel mixture in the cylinder.
Maintenance Costs: The ATV ignition coil is a common wear item; therefore, it is not recommended to purchase a used coil as a replacement. Fortunately, the ignition coil is relatively inexpensive.