To sum up, the balance shaft is used to balance and reduce the vibration of the motorcycle engine, so as to reduce the engine vibration, reduce the engine noise, extend the service life of the engine, and improve the comfort of the driver and passengers. Purpose. As a patent, it was first used by YAMAHA motorcycles and has achieved good results. Balance shafts are used in every model built by Yamaha. This is also its feature and selling point. Among similar models, It is undoubtedly the quietest.