A four-stroke internal combustion engine (20) is provided. There is provided within an engine housing (28) an oil reservoir (126) and a valve chamber (156) which independently communicate with a crank chamber (124). A strategically placed divider (116) and passageway, located within the engine housing (28), appropriately direct lubricant within the engine housing (28) so that the internal cavity of the engine is lubricated during use in various operating attitudes, and so that the fluid flows to and is held in the proper chambers of the engine housing during storage. There is also provided a breather arrangement for an internal combustion engine (20) which includes a cam shaft (98) having a hollow passageway in communication wit the crank chamber (124) and the air intake system of the engine. There is also provided an engine housing which can be utilized for engines having different horse power ratings. There is also provided a crankshaft bearing assembly (68, 70) which prevents damage to the bearing upon insertion of the crankshaft (80) into the crank chamber (124).