Abstract: Improvements in a fuel injected, internal combustion engine having a first passage for flow of air into the combustion chamber and exit of exhaust gases from the combustion chamber and a single poppet valve opened and closed in timed relation to rotation of the engine's crank shaft to control flow of gases through such first passage wherein the improvement comprises an inlet air passage and an exhaust gas passage each communicating with the first passage and one another and a diverter valve moveable in timed relation to operation of the poppet valve selectively to direct, in one position, air into the combustion chamber through the inlet passage and, in another position, exit of exhaust gases through the outlet passage and another position therebetween where air flowing in the inlet passage flows directly to the outlet passage following the exhaust portion of the cycle to assist in driving out the exhaust gases.