The durability and lifespan of a chain sprocket can vary depending on several factors such as the quality of the sprocket, maintenance practices, riding conditions, and the overall usage of the motorcycle. While I don't have specific information regarding the Thunderbird 350's chain sprocket, I can provide you with a general estimate.
On average, a well-maintained chain sprocket can last anywhere from 15,000 to 30,000 kilometers. However, this is just a rough estimate, and it's important to note that individual experiences may vary. Regular maintenance tasks such as proper lubrication, tension adjustments, and cleaning can help prolong the lifespan of the sprocket and the entire chain drive system.
To get more accurate information regarding the lifespan of the chain sprocket for the Thunderbird 350, it's best to consult the motorcycle's manufacturer or refer to the owner's manual for specific maintenance guidelines and recommendations.