Abstract: There is disclosed a motorcycle parking brake device adapted to be mounted to the master cylinder of a braking system. The brake device includes a bolt portion with a stem portion which extends to a head having a flange. The stem portion includes a threaded portion, a cylindrical first seat, a recessed portion, and a second seat. The stem portion has a stem channel with an O-ring slot containing an O-ring seal. A hydraulic fluid opening extends through the recessed portion and into the stem channel. The central stem channel extends to a head channel. A plunger is coupled to the bolt portion for reciprocal movement between a disengaged position and an engaged position. The plunger has a shank, a piston, and a push plate. The brake device also has a seal fitted about the second seat and a resilient D-ring seal fitted about the first seat.