Electrical Parts

Spark Plugs

Spark plugs transmit the high voltage from the ignition coil into the engine's combustion chamber in the form of a spark that must 'jump', or arc, between electrodes that form a gap to ignite the air-fuel mixture. Spark plugs are continuously exposed to extremely high-temperatures and pressures inside the engine, which erode the electrodes over time which will require more voltage from the ignition system. When the service life of the spark plug is reached, they must be replaced to restore engine performance. Inspect for wear and fouling every 4000 mi (7000 km) or 6 months, and the target for replacing them is every 12000 mi (20000 km) or 18 months.


The battery provides the electrical power to start the vehicle and to power electrical components when the engine RPM is low. There are 2 types of batteries: conventional and maintenance-free. Both types have a normal life expectancy, and when the battery power decreases too much, the operation of the starter motor will become weak, and the vehicle will be difficult to start. The voltage potential of both types of batteries should be periodically checked and the battery replaced if needed. Conventional type batteries also require periodic refilling of the battery fluid with distilled water.

Light Bulbs

Motorcycles use incandescent type light bulbs for several functions. These bulbs can fail, or "burn out", for several reasons; the normal life of the light-emitting portion of the bulb is reached, the bulb is subject to an impact if the motorcycle tips over, and electrical problems causing excessive voltage. Headlights and tail lights are obviously necessary for safe operation, and some models use several incandescent bulbs in the instrument panel as warning and indicator lights. Riders need to check that all lights are working before each ride, and replace any failed bulbs to ensure safe operation and to prevent damage to the unit. If a particular light does not function after replacement, there may be some type of electrical failure, so the vehicle will need to be inspected and repaired by a Yamaha dealer.