No, it is not necessary for all motorcycle riders to rev the engine loudly when starting their motorcycles. Revving the engine loudly during startup is primarily a matter of personal preference and style rather than a functional requirement. Some riders may choose to rev the engine to create a distinctive sound or make a statement, but it is not a mandatory practice.
Revving the engine excessively and creating loud noises can be seen as unnecessary and potentially disruptive, especially in residential areas or other noise-sensitive environments. It is important for riders to be considerate of others and abide by local noise regulations.
Most modern motorcycles are designed to start smoothly and run quietly at idle. The engine management systems are calibrated to provide a consistent and stable idle speed without the need for excessive revving. It is generally recommended to start the motorcycle with a moderate rev, allowing the engine to settle into its normal idle speed.
Ultimately, how a rider starts and revs their motorcycle is a matter of personal choice, but it's always good practice to be mindful of noise levels and respect the peace and quiet of the surrounding environment.