In an improved air inlet valve assembly, a flow of air along a first or second flow path may be controlled by a position of air inlet guide surfaces of a rotatable valve relative to air inlet guide slots of a fixed valve sleeve. Air flowing along the first flow path may rotate a motor in a first direction to operate the tool in a forward mode. Air flowing along the second flow path may rotate the motor in the second direction to operate the tool in a reverse mode. In the forward mode, as air flows along the first flow path, air may be discharged along a primary discharge path, with a portion of the second flow path providing a secondary discharge path. In the reverse mode, as air flows along the second flow path, air may be discharged along the primary discharge path, with a portion of the first flow path providing the secondary discharge path.