an internal combustion engine can comprise a crankcase , and a crankshaft rotatably supported in the crankcase . the crankshaft includes a drive sprocket attached thereto . a cam chain engages the drive sprocket , and a cam chain chamber houses at least a part of the drive sprocket and cam chain therein . the cam chain chamber is configured to pool oil in a lower portion thereof . a balancer is coupled to the crankshaft and is configured to be rotated by rotational power transmitted from the crankshaft . the balancer is also disposed within the cam chain chamber , and is configured to splash oil pooled in the cam chain chamber during the rotation thereof . the engine also comprises a wall portion disposed in the cam chain chamber . the wall portion is configured to cover an upper portion of the balancer , and is disposed adjacent to a periphery of the balancer .