Internal combustion engine with balancer shaft and method of assembling the same

摘要

An internal combustion engine includes a balancer housing (3), a balancer shaft (4) having an eccentric weight portion (4A) and disposed within the balancer housing (3) so as to be parallel with and rotatable in timed relation with a crankshaft (2), and a power transmitting mechanism (10) that transmits rotation of the crankshaft (2) to the balancer shaft (4), wherein the balancer shaft (4) has an end portion (6) protruding outward of the balancer housing (3), and wherein the end portion (6) of the balancer shaft (4) is partially cut to have a flattened section (8) that constitutes a device for positioning the balancer shaft (4) in a predetermined rotational position. A method of assembling an internal combustion engine with a balancer shaft (4) is also provided.