Sport bikes typically don't use V-twin engines like many cruisers for several reasons:
Performance and high RPM: Sport bikes are designed for high-performance riding, often emphasizing speed, agility, and acceleration. V-twin engines, while providing good low-end torque, may not be as suitable for achieving high RPM (revolutions per minute) and generating the high horsepower levels that sport bikes demand. Inline engines, such as inline-four or inline-triple configurations, are commonly used in sport bikes for their ability to rev higher and deliver more power at higher RPM ranges.
Weight and compactness: Sport bikes aim for lightweight construction to enhance maneuverability and handling. V-twin engines, especially larger displacement ones, tend to be heavier and physically larger than inline engines of similar power output. By utilizing inline engines, sport bike manufacturers can achieve a more compact and centralized mass distribution, which contributes to improved handling characteristics.
Center of gravity: The layout of V-twin engines places a significant portion of the engine's mass lower in the frame, which can lead to a lower center of gravity. This configuration provides stability for cruisers, which prioritize comfortable and relaxed riding. In contrast, sport bikes often adopt a more forward-leaning riding position, and a higher center of gravity allows for more aggressive cornering and maneuvering at higher speeds.
Engine characteristics and power delivery: V-twin engines typically deliver torque in a more linear and accessible manner, which suits the cruising and low-speed riding style commonly associated with cruisers. In contrast, sport bikes require engines that deliver power more explosively, with a strong emphasis on high-end power delivery. Inline engines, particularly inline-four configurations, offer a smoother power band, higher RPM limits, and a more aggressive power delivery that aligns with the performance-oriented nature of sport bikes.
Design heritage and tradition: The choice of engine configuration is also influenced by design heritage and the brand identity of different motorcycle manufacturers. Cruisers, including Harley-Davidson and Buell, have a strong association with V-twin engines, and the sound, feel, and aesthetics of the V-twin engine contribute to the unique character and appeal of cruiser motorcycles. Sport bike manufacturers often focus on inline engines to align with their racing heritage and emphasize high-performance attributes.
It's important to note that while these are general reasons why sport bikes typically use inline engines rather than V-twin engines, there can be exceptions and variations among different motorcycle models and manufacturers.