What Causes a Motorcycle Spark Plug to Not Discharge?

[DelGabriela]

Motorcycle spark plugs do not discharge due to a malfunction in the ignition system. Motorcycle spark plug power supply principle: The 15KV voltage on a motorcycle spark plug is generated by a dedicated high-voltage circuit. Inspection methods: Check whether the motorcycle battery has power or if there is voltage but no current output. The motorcycle battery supplies power to the self-excited oscillation circuit for ignition, which converts it into the low-voltage pulse voltage required by the low-voltage coil of the high-voltage coil. If the battery has no power, it cannot generate the low-voltage pulse voltage, preventing the high-voltage coil winding from producing a high-voltage pulse. This results in no voltage on the spark plug, making ignition impossible. Old batteries may show voltage but fail to output current when in use. Solution: Replace with a new battery for testing. If the power supply line from the motorcycle battery to the self-excited oscillation circuit is disconnected or has poor contact, the self-excited oscillation circuit cannot generate the low-voltage pulse voltage required by the low-voltage coil of the high-voltage coil. This prevents the high-voltage coil winding from producing a high-voltage pulse, resulting in no voltage on the spark plug and making ignition impossible. Solution: Carefully check for broken copper traces, cold solder joints, or other circuit disconnection issues. If the transistor or oscillation module in the self-excited oscillation circuit is damaged, or if the inverter capacitor is faulty, no low-voltage pulse will be generated. This prevents the high-voltage coil winding from producing a high-voltage pulse, resulting in no voltage on the spark plug and making ignition impossible. Solution: Remove the transistor and test it with a multimeter to check for damage. Use the multimeter's capacitance setting to measure if the capacitor's capacity has changed. If any part of the self-excited oscillation circuit, its power supply, the low-voltage winding of the high-voltage coil, or the high-voltage winding is disconnected, the high-voltage coil winding cannot produce a high-voltage pulse. This results in no voltage on the spark plug, making ignition impossible. Solution: Carefully inspect the connecting wires and copper traces for breaks, cold solder joints, or other issues.