Riding a motorcycle at a constant speed for a long time generally does not have a detrimental effect on the engine. In fact, many motorcycles are designed to handle sustained highway speeds without any issues. Modern motorcycles are engineered to withstand prolonged riding at consistent speeds.
It's important to ensure that the motorcycle is properly maintained, including regular oil changes, filter replacements, and overall servicing. Long rides may put more strain on certain components, such as the clutch, brakes, and tires, so it's important to check their condition before embarking on a lengthy trip.
Regarding cruise control, it is a feature designed to help riders maintain a constant speed without having to keep their hand on the throttle. Cruise control is primarily useful for reducing fatigue during long highway rides, improving fuel efficiency, and providing more comfort. It does not inherently cause harm to the engine or any other components of the motorcycle.
In summary, as long as your motorcycle is well-maintained and in good condition, riding at a constant speed for an extended period should not pose a significant risk to the engine.