Stroke & Bore
An engine's bore is the diameter of each cylinder, while the stroke is the distance within the cylinder the piston travels
It is the point in which the piston of your engine is at its highest point on the compression stroke.
BDC
It is the lowest point that the piston reaches
Swept Volume (Vs)
Volume swept by the piston from TDC to BDC
Vs= Area x Length
Clearance Volume (Vc)
Clearance volume is a volume between the cylinder head and the piston top when the piston is at top dead center
Volume of the Cylinder (Va)
Va = Vs+Vc
Compression Ratio
compression ratio is defined as the ratio of total volume of the engine cylinder (ie..both clearance and stroke volume ) to the clearance volume
=Va/Vc