It is not too late to replace a motorcycle spark plug every 15,000 miles. In fact, 15,000 miles is a typical interval for spark plug replacement in motorcycles, although this can vary depending on the specific model and manufacturer recommendations.
Spark plugs play a crucial role in the combustion process by igniting the fuel-air mixture in the engine cylinder. Over time, spark plugs can become worn, fouled, or develop deposits, which can negatively impact their performance. As a result, replacing spark plugs at regular intervals helps ensure optimal engine performance, fuel efficiency, and reliable ignition.
If you have reached or exceeded the 15,000-mile mark and have not yet replaced your motorcycle's spark plugs, it is advisable to do so as soon as possible. By replacing them, you can help maintain the engine's efficiency and prevent potential issues such as misfires, rough idling, or decreased power. Additionally, be sure to consult your motorcycle's owner manual for specific recommendations regarding spark plug replacement intervals for your particular model.