Four-stroke internal combustion engine

A four-stroke internal combustion engine, comprising:

• an engine housing having an oversized wrist pin boss, said boss being machinable to include at least a first aperture in one location and a second aperture in another location;
• a cantilevered crankshaft disposed within said engine housing;
• a piston reciprocally operable within said engine housing, said piston including an aperture;
• a connecting rod having opposite ends, one end of said connecting rod being pivotally attached to said crankshaft, and the other end of said connecting rod being pivotally connectable to said piston;
• and
• a wrist pin which is passable through said first aperture in said boss into said aperture of said piston and into one end of said connecting rod to pivotally connect said connecting rod to said piston to provide a first throw of said engine, and which is also passable through said second aperture of said boss into said aperture of said piston and into one end of said connecting rod to pivotally connect said connecting rod to said piston to provide a second throw of said engine.

A four-stroke internal combustion engine comprising:

• a crankshaft;
• a blower housing having a hub which includes an extension, said hub adapted to fit over said crankshaft;
• a starter assembly surrounded by said blower housing and positioned onto said hub extension, said starter assembly adapted to cooperate with said crankshaft to start the engine;
• and
• an annular ring positioned over said extension to prevent axial movement of said starter assembly.

A method of assembling a four-stroke internal combustion engine, comprising the steps:

• providing an engine housing having an integrally formed crankcase, cylinder and flywheel back plate;
• providing a mounting boss on said back plate;
• mounting said engine to an assembly fixture by positioning a pin on the fixture into said mounting boss;
• placing a shroud around said engine housing while said engine remains mounted to said fixture;
• and
• attaching said shroud to said engine housing while said engine remains mounted to the assembly fixture.

A four-stroke internal combustion engine, comprising:

• an engine housing including a crankcase and a cylinder;
• a crank chamber disposed within said crankcase;
• a crankshaft supported for rotation within said crank chamber;
• a piston operably interconnected with said crankshaft for reciprocation within said cylinder in response to rotation of said crankshaft;
• an oil reservoir disposed within said crankcase, and in fluid flow communication with said crank chamber;
• an arcuate divider at least partially separating said crank chamber from said oil reservoir;
• and
• a depending wall extending at least partially into said crank chamber to define a lubricant receiving space between said divider and said depending wall.

A four-stroke internal combustion engine, comprising:

• an engine housing;
• including a crankcase and a cylinder;
• a crankshaft supported for rotation within said crank chamber;
• a wrist pin boss on said engine housing, said wrist pin boss being large enough to permit an access hole to be machined thereinto at one of at least two locations;
• a piston reciprocally operable within said cylinder, said piston including an aperture, said access hole and aperture being alignable during assembly of said engine;
• a connecting rod having one end pivotally attached to said crankshaft and the other end pivotally connected to said piston;
• and
• a wrist pin insertable through said access hole and into said aperture in said piston to pivotally connect said connecting rod to said piston;
• wherein the location of the access hole in the wrist pin boss is selected to accommodate a desired connecting rod length.

A four-stroke engine capable of being operated in a tipped position, said engine comprising:

• an engine housing, including a crankcase and a cylinder, said crankcase including a reservoir adapted to contain a lubricant;
• a combustion chamber at least partially defined by said cylinder;
• intake and exhaust valves communicating with said combustion chamber;
• a piston reciprocal within said cylinder;
• a crankshaft supported for rotation within said crank chamber and connected with said piston to convert linear movement of said piston into rotation of said crankshaft, said crankshaft supported by a bearing;
• a cam shaft oriented normal to said crankshaft and rotatable in response to rotation of said crankshaft to actuate said valves;
• and
• a crank chamber disposed within said crankcase, wherein said cam shaft has an axial passageway and a radial aperture which communicates with said crank chamber and said passageway, the cam shaft receiving lubricant from the reservoir through said bearing.

A four-stroke internal combustion engine, comprising:

• an engine housing, including a crankcase and a cylinder;
• a crank chamber disposed within said crankcase;
• and
• a cantilevered crankshaft supported for rotation within said crank chamber, said crankshaft including a counterweight having a locating hole extending therethrough to accommodate a tool for proper insertion of said crankshaft into said crank chamber.

A four-stroke internal combustion engine, comprising:

• an engine housing, including a crankcase and a cylinder;
• a crank chamber disposed within said crankcase;
• a crankshaft supported for rotation within said crank chamber;
• a piston operably interconnected with said crankshaft for reciprocation within said cylinder in response to rotation of said crankshaft;
• a shroud at least partially surrounding said engine housing and including a pair of opposed channels;
• and
• a fuel tank having opposed outwardly-extending shoulders, such that said shoulders of said fuel tank are received by said respective channels of said shroud.

A four-stroke internal combustion engine, comprising:

• an engine housing including a crankcase, a cylinder, and a back plate;
• a flywheel adjacent to said back plate;
• a crank chamber disposed within said crankcase;
• a crankshaft supported for rotation within said crank chamber;
• and
• a piston operably interconnected with said crankshaft for reciprocation within said cylinder in response to rotation of said crankshaft;
• wherein said crankcase, cylinder, and back plate are cast as a single component.

An L-head, internal combustion engine, comprising:

• an engine housing including a crankcase and a cylinder, said cylinder including intake and exhaust ports on opposite sides of said engine housing, the intake and exhaust ports being elliptical in a cross-section taken perpendicular to the longitudinal axis of each respective port;
• intake and exhaust valves in communication with said intake and exhaust ports, respectively;
• a crank chamber disposed within said crankcase;
• a crankshaft supported for rotation within said crank chamber;
• and
• a piston operably interconnected with said crankshaft for reciprocation within said cylinder in response to rotation of said crankshaft.