Engine basics

Who and what year was the  four stroke engine invented.
Nikolaus Otto invented the 4 stroke engine in 1876. It is also known as the Otto Cycle.
What is the purpose of the crankshaft,camshaft,vavles collects(keepers),vavle sterm seals,head gasket,pistons,piston rings name them all, cambelt,flywheel?
The crankshaft is the component in the bottom end of the engine. It is what turns the up and down motion of the pistons into rotory motion that drives the wheels. The camshaft is what makes the valves open and close. It does this using the lobes, which as they turn presses down on the valve. The valve collets are what hold the valve in place and in conjunction with the spring, hold the valve closed and holds pressure on it so it stays closed until the rotating camshaft forces the valve down, against the spring. The valve stem seals are there to stop oil from the top of the head, seeping down through the valve guides and into the combustion chamber.
The head gasket is a seal. It stops water from entering the cylinders, and exiting the water jacket. It basically does the same for oil. It also stops the air and fuel mixture from leaking out of the combustion chamber under compression. The piston is what provides the up and down movement that is needed to make the rotating movement. The piston rings are what stops the air/fuel mixture leaking past the piston, and also stops the oil from the crank case getting into the cylinder. There are 2 seperate compression rings and 2 oil rings, which are in the same gap, seperated by the spacer ring. The cambelt is what connects the crank shaft to the camshaft which provides the rotating motion to open and close the valves. The fly wheel is a disc which is connected to the crankshaft. It is basically a weight which provides momentum to the engine, so it wont stall.
What is the bore and stroke.
The bore is the diameter of the cylinder, the distance across the cylinder. The stroke is the distance that the piston moves up and down the cylinder.

Head Gasket

Cam belt

Fly Wheel

Crankshaft

Valve Stem seal

Piston Ring



Valve and Collets



Piston