Four-cycle engine having improved lubricating mechanism

A four-cycle engine providing an intake valve, an exhaust valve, and an ignition plug on the top of a cylinder, and supplying a mixed gas composed of a fuel and air, said engine comprising:

• an inlet for the mixed gas perforated on a cylinder wall so that a lubricating mixed gas composed of fuel and air and also previously containing a lubricating oil is supplied to the cylinder, said inlet being provided at a portion of the cylinder wall where said inlet is opened at a portion near the top dead point of the piston, and said inlet is closed by the piston in the ascending or descending stages other than the portion near the top dead point of the piston;
• a passage for the lubricating mixed gas provided so that the lubricating mixed gas containing the lubricating oil, which is pushed to the crank chamber in the stage of descending the piston, is pushed out of an outlet of the lubricating mixed gas perforated on the crank chamber or cylinder wall, said lubricating mixed gas then passes through said passage including a valve gear mechanism provided outside of the crank chamber or the cylinder wall, and said lubricating mixed gas is transferred to the intake valve placed at the top of the cylinder;
• and
• a lead valve provided between the inlet of the lubricating mixed gas and the outlet of the passage communicating with the carburetor so that the lubricating mixed gas never flows back to a carburetor side of said engine,
• wherein said valve gear mechanism drive a movement of said intake and exhaust valves.