Abstract: A two-piece intake assembly such as a coaxial poppet valve includes a main poppet valve with a stem attached to a head and an auxiliary poppet valve movable on the inner valve. A guiding element on the outer valve is configured to receive the inner valve stem, and is connected to an outer valve head configured to mate with the inner valve head and form a seal. The assembly provides a first vent opening formed by the action of a rocker arm on the inner valve stem and a second opening formed by the pressure differential between the combustion chamber and the intake port.