What is a common sign of engine overheating in a motorcycle?

Smoke or steam coming from the engine is a clear and immediate indication of engine overheating in a motorcycle. When an engine overheats, the coolant can begin to boil and escape as steam, or oil and other fluids can burn off, creating smoke. This phenomenon serves as a visible signal to the rider that the engine is experiencing temperatures beyond its normal operating range, which can lead to severe damage if not addressed promptly.

The other signs mentioned, while potentially related to engine performance issues, are not direct indicators of overheating. A decrease in fuel efficiency may occur due to various factors, including engine wear or misalignment, but it does not specifically point to overheating. Excessive engine noise might suggest mechanical issues such as poor lubrication or loose components, rather than overheating. Lastly, hard starting could indicate fuel system problems or issues with electrical components but is not a direct symptom of high engine temperatures.