Stroke and Clearance Volume:
Stroke
The distance traveled by piston from the topmost positions of it (also called Top dead centre TDC), to its bottom most position (or bottom dead centre BDC) is called as stroke it will be two times the crank radius. It can be denoted by letter h. Units mm or inches (S.L, Metric). Now we can compute the swept volume as given below: (L = 2r)
V_{s} = D^{2}/4.L
If D is in cm and L is in cm than the units of V will be cm3 which is written as cubic centimeter or c.c.
Clearance Volume
The volume above T.D.C is termed as clearance volume, this is provided to accommodate engine valves etc. this can be referred as (VC).Then total volume of engine cylinder
V =V_{S} + V_{C}