What is the difference between two-valve and four-valve motorcycle engines?

[ColtonAnn]

The differences between two-valve and four-valve motorcycle engines include varying compression ratios, performance characteristics, and thermal efficiency. Compression ratio differences: In single-cylinder motorcycle engines of the same displacement, a four-valve design with dual overhead camshafts increases intake volume, enhances the engine's compression ratio, and accelerates exhaust gas expulsion, thereby improving the engine's compression ratio. Performance differences: Under the same displacement, a four-valve engine will undoubtedly outperform a two-valve engine in terms of power. However, it demands higher fuel quality and, to some extent, shortens the engine's lifespan compared to a two-valve engine. The likelihood of encountering issues later on is also greater. Thermal efficiency differences: When prioritizing performance, opting for a four-valve engine is more reliable, given its higher thermal efficiency and superior power output.