Abstract: An internal combustion engine has an integral cylinder head, a one-piece connecting rod, and a crankshaft disposed at the interface between the first engine housing and the second engine housing. In an overhead cam shaft embodiment, the cam shaft drive means includes first and second gearsets of cross-helical gears. Also directly mounted to the cam drive shaft are the oil slinger, the centrifugally-responsive speed governor components, and the auxiliary power take-off shaft. This arrangement eliminates the need for additional shafts and subassemblies. In another embodiment, both the crankshaft and the cam shaft are disposed at the interface between the two engine housings to decrease manufacturing and assembly costs. The crankshaft and/or cam shaft bearings are formed integral with the engine housings to eliminate the need for separate bearing components.