STRADDLED VEHICLE ENGINE UNIT AND STRADDLED VEHICLE

Provided is a straddled vehicle engine unit including two or more cylinders and mounted to a straddled vehicle, the straddled vehicle engine unit capable of detecting a misfire in an internal combustion engine with high accuracy over a wide operation range. The straddled vehicle engine unit includes an internal combustion engine and a misfire detection device. The misfire detection device includes a crankshaft rotation speed fluctuation physical quantity acquisition unit and a misfire determination unit that determines a misfire state. The misfire determination unit includes a first determination unit, a second determination unit, and a third determination unit. The first determination unit determines whether or not the crankshaft rotation speed fluctuation physical quantity acquired by the crankshaft rotation speed fluctuation physical quantity acquisition unit is greater than a set physical quantity determination reference. The second determination unit determines whether or not a fluctuation pattern constituted by a physical quantity and the crankshaft rotation speed fluctuation physical quantity acquired at least before or after the physical quantity falls within a set misfire pattern range. The third determination unit determines whether a misfire determination is to be set as effective or not, based on a result of the determination by the first determination unit and a result of the determination by the second determination unit.