Yes, it is generally acceptable to use regular unleaded gasoline in a Honda motorcycle unless otherwise specified by the manufacturer. Most Honda motorcycles are designed to run on regular unleaded gasoline, which typically has an octane rating of 87 or higher.
Using regular unleaded gasoline that meets the recommended octane rating specified by Honda will not cause harm to the engine or negatively impact the motorcycle's performance. It's important to follow the manufacturer's guidelines regarding fuel type and octane rating, which can usually be found in the owner's manual or on the motorcycle itself.
Using higher octane fuel than recommended does not provide any significant benefits unless the motorcycle specifically requires a higher octane rating. However, using lower octane fuel than recommended can potentially lead to knocking, reduced performance, and engine damage, especially in high-performance or high-compression engines.
If you have any doubts about the appropriate fuel for your specific Honda motorcycle model, it's always best to consult the owner's manual or contact a Honda dealership or authorized service center for precise recommendations based on your motorcycle's requirements.