Why does the two-stroke engine does not have a camshaft?*1 pointC. Camshaft is not neededD. All of the aboveB. It uses portsA. Has no valves

Understanding the Two-Stroke Engine Design

1. Basic Engine Configuration: Two-stroke engines are designed to complete a power cycle with every two strokes of the piston (one crankshaft revolution). Unlike four-stroke engines, they simplify the engine mechanics.

2. Role of Valves and Camshaft: Four-stroke engines generally use camshafts to operate valves (intake and exhaust), which are necessary to manage the flow of air and fuel into the combustion chamber and the exhaust out. In contrast, two-stroke engines do not employ traditional valves.

3. Use of Ports: Two-stroke engines utilize exhaust and intake ports rather than valves. These ports open and close based on the position of the piston. When the piston moves down during the power stroke, it uncovers the intake port, allowing the fuel-air mixture to enter the combustion chamber. Similarly, as the piston moves back up, it covers the intake port while opening the exhaust port, allowing exhaust gases to escape.

4. Conclusion: Because the two-stroke engine relies on ports rather than valves, there is no need for a camshaft, which typically serves to control valve timing in other types of engines.

Final Answer

The reason a two-stroke engine does not have a camshaft is that it uses ports instead of valves to manage fuel and exhaust flow. Thus, the correct answer is C. Camshaft is not needed.