Where is the balance shaft located on a motorcycle?
2 Answers
On the crankcase of a motorcycle engine, there is a large protrusion, which indicates that the motorcycle has a balance shaft. However, some motorcycle engines without balance shafts may also have a smaller protrusion on the crankcase. The balance shaft helps reduce vibrations during engine operation, and many vehicles are equipped with balance shafts. Here is some related information about balance shafts: 1. The balance shaft is essentially a simple shaft with counterweights. When the crankshaft rotates, the balance shaft rotates in the opposite direction, thereby offsetting some of the vibrations. The working principle of balance shafts in cars is the same as described above. 2. Some high-end car engines even feature two balance shafts. Three-cylinder engines, due to their inherent structural limitations, tend to produce noticeable vibrations during operation, so balance shafts are used to reduce these vibrations.
I specialize in motorcycle repairs. The balance shaft is actually hidden on the side or bottom of the engine, and its exact location depends on the specific model design. For mid-to-large displacement bikes like the CB400, the balance shaft is usually installed inside the crankcase and driven by the crankshaft rotation. Its working principle is particularly interesting: it uses counterweights to generate reverse vibrations, specifically designed to offset the shaking caused by the piston's up-and-down movement. That's why some bikes have minimal vibrations at idle—it's all thanks to a well-designed balance shaft! If you want to locate it, you'll need to remove the engine side cover to see it.
