Describe the reciprocating engine cycle.

Description should include the following concepts:

• The intake stroke begins as the piston starts its downward travel. When this happens, the intake valve opens, and the fuel-air mixture is drawn into the cylinder.
• The intake, compression, power, and exhaust processes occur in four separate strokes of the piston.

Process/Skill Questions:

• What is a piston, and how does it work?
• What happens at each stoke of the piston?