A pneumatically actuated valve assembly for use as intake and/or exhaust valves on two- or four-stroke internal combustion engines. The assembly includes a valve (100), valve housing (200), and compressed gas distribution and timing mechanisms (FIGS. 5 8). The valve (100) is comprised of a short light weight hollow cylindrical body with a capped lower end and an opened upper end. The valve is further defined by a plurality of ports (104) adjacent to the lower end and a collar (198) encircling the body adjacent the upper end. The valve housing (200) is hollow and tubular having a larger diameter upper section and a smaller diameter lower section in which the valve (100) slides up to close and down to open. The housing (200) further includes hollow channels which direct compressed gas, managed by the distribution and timing mechanism, alternately towards the areas above and below the valve collar at regular intervals to open and close the valve, respectively.