Intake
First stroke, starts with piston at TDC (Top Dead Center). This term refers to the location of both the piston and the crankshaft. TDC refers to the point where the piston is at the top of the bore and the crankshaft is at 0 degrees of rotation. Due to the geometry involved in connecting the pistons linear travel to the crankshafts circular motion, it is possible to have the piston at the top of the bore and the crankshaft located some degrees before or after 0 degrees of rotation.

Compression
when the crankshaft has reached 180 degrees after TDC, it is referred to as BDC or Bottom Dead Center. At this point the piston is at the bottom of the bore and is ready to begin its travel back up the bore to compress the air and fuel taken in on the intake stroke.

POWER
When the piston returns to the top of the bore again, the crankshaft is now at 360 degrees of rotation. At this point the mixture ithat is compressed is expanding rapidly because of the combustion event caused by the ignition system firing the spark plug. This expansion is where the negine produces its power and actually forces the piston back down the bore and applies rotational force to the crankshaft.

EXHAUST
The Final stroke begins when the piston returns to BDC and begins to push the expanded and burned up gases back up and out of the cylinder to clear it for the next incoming cycle. At this point the crankshaft is at 540 degrees of rotation and will complete the cycle at the top of the cylinder at 720 degrees of rotation.

Real PRESSURE-VOLUME (p-V) Cycle (look it up)

Also look up:
Engine Revs vs Engine CYCLEs

Volumetric Efficiency

Standard Conditions

Absolute Conditions

Air Density
Air Flow

Mass Flow

KPA/BAR vs INHG/PSI

Brake SPecific Fuel Consumption

Brake Specific Air Consumption

Lambda

Learn all that an you will know more than 99% on this site an other sites, and more than most "engineers"