321cc

321cc is a term that can refer to several things, most commonly a unit of engine displacement. Engine displacement is the volume of air and fuel that an engine's cylinders can displace, or move, during one complete cycle of the piston. It is typically measured in cubic centimeters (cc) or liters. A 321cc engine would therefore have a total cylinder volume of 321 cubic centimeters. This size of engine is often found in smaller motorcycles, scooters, and some personal watercraft. The exact performance and characteristics of a 321cc engine will vary depending on its design, number of cylinders, and other factors.

In other contexts, "321cc" might be a specific product model number, a company name, or an identifier in a particular field, such as software or a scientific study. Without further context, the interpretation as engine displacement is the most prevalent. For example, a popular model of small-displacement motorcycle might be advertised as having a 321cc engine, highlighting its relatively compact size and fuel efficiency.