Abstract: An internal combustion engine having a bi-diameter or stepped piston configuration. The piston having a smaller upper piston portion and a larger lowre piston portion. A pumping chamber is formed in part by the larger lower piston portion separate from each of the crankcase and combustion chamber. Fluid reaches the pumping chamber from outside the pump/engine and is pumped-out beyond the pump/engine. The pumped fluid never communicates with either of the sealed crankcase or combustion chamber.

Abstract: An internal combustion engine having a bi-diameter or stepped piston between a combustion chamber and crankcase. Piston outlet means is provided in the smaller upper piston portion which permits mixture from the crankcase to pass through to a mixture channel. The mixture channel leads to ports in the upper cylinder portion forming the combustion chamber. A pumping chamber is formed in part by the larger lower piston portion seperate from the crankcase.

Abstract: An automatic impact delivering device or tool of the internal combustion type having a self-contained fuel supply, wherein:1. valving is an integral function of the piston;2. a pre-compression chamber and a combustion chamber are provided in the same structure;3. there is only one major moving part;4. a spark plug is fired by an ignition means, the ignition means being movable to enable the operator to change the power output of the device by changing the compression ratio of the fuel and air mixture in the combustion chamber;5. a fuel metering system is an integral part of the piston and cylinder, thus not requiring any additional moving parts; and6. the device is loaded by a single spring disposed wholly internally thereof.