Four stroke engines must have at least 2 valves: one exhaust and one intake. Most modern engines are going to 4 valves per cylinder to allow the intake and exhaust strokes to be more efficient.
Valves
This engine (allowing it is an automotive engine) is a four valve per cylinder engine.
if you see the difference between valves
An engine may have two, three, or four valves per cylinder.
An engine may have two, three, or four valves per cylinder.
valves are use in four stroke engine, and ports are use in two stroke engine.
The camshaft operated the inlet and outlet valves in the cylinder to admit fuel to the engine before ignition and expel the exhaust gas after the power stroke. The camshaft operates at half the crankshaft speed in a four-stroke engine.
Intake valve and exhaust valve.
It depends on which valves you are referring to. On a four stoke engine there are at least two per cylinder.
Some two stroke engines have 4 valves, Detroit Diesel 71 series and 53 series engines for example. Most small 2 stroke engines have no "Valves" at all in the sense of the "POP" valve used in four stroke engines. Some people feel these engine has one valve because the piston acts as the valve covering the ports cut into the cylinder walls.
two
two