Power unit, vehicle and method for controlling power unit

The vehicle and the power unit include: an engine; and a control apparatus that controls combustion of the engine, in which a bore diameter of the engine is 45 mm to 60 mm, and the control apparatus includes a knock sensor that detects vibration of the engine. The control apparatus extracts, from a detection signal of the knock sensor, components in a primary frequency band that is a lowest frequency band among a plurality of frequency bands in which peaks of knocking vibration are distributed according to the bore diameter of 45 mm to 60 mm, with a larger gain than that of components in a secondary frequency band that is a second lowest frequency band. The control apparatus determines that knocking occurs based on a detection signal in which the components in the primary frequency band are extracted with a larger gain than that of the components in the secondary frequency band, and controls the combustion of the engine based on a determination result of the occurrence of knocking.