Timing chains and tensioners are essential for the precise control of valve timing in a motorbike engine. The timing chain connects the crankshaft to the camshaft and ensures that the valves open and close at the right time. A chain tensioner keeps the timing chain at the correct tension to prevent the chain from jumping and thus incorrect valve timing. A worn or defective tensioner can lead to chain slippage and serious engine damage. Regular maintenance and inspection of these components are crucial for the longevity and performance of the engine.