Understanding Camshaft Gear Ratios

In a 4-stroke engine, the gear ratio between the crankshaft and the camshaft is invariably 2:1. This signifies that for every two rotations of the crankshaft, the camshaft completes a single rotation. Maintaining this 2:1 ratio is crucial for the engine's proper functioning.

The cam sprocket located at the top will possess twice the number of teeth compared to the crankshaft cam-chain sprocket. For instance, engines such as the Honda 50, 50-110cc Chinese models, and the Lifan 140 typically feature cam sprockets with 28 teeth. Conversely, engines like the Jailing, GPX, and YX 140 are equipped with cam sprockets containing 32 teeth.

When upgrading to a performance camshaft, it may be necessary to replace the cam sprocket. However, this replacement should only be considered if the bolt pattern requires it.