A finger-operated lever device to be installed on a handlebar of an All-Terrain Vehicle (ATV) or other applicable vehicle, for actuating a cable to cause acceleration of the internal combustion engine of the vehicle. The lever device includes a housing, an internal first lever assembly connectable to the cable, and an external second lever assembly. The external lever assembly and the internal lever assembly are connected so that user operation of the external lever assembly causes the internal lever assembly to rotate. The external lever assembly is divided into two portions, a support member and an extension member. The extension member can be adjusted at different angles to the support member, allowing the user to set the angle of the lever to most comfortably fit to his or her riding posture.