What maintenance task can help improve fuel efficiency in a two-stroke engine?

Cleaning or replacing the air filter is crucial for maintaining fuel efficiency in a two-stroke engine. The air filter plays a significant role in ensuring that the engine receives the appropriate amount of clean air for combustion. If the air filter is clogged or dirty, it restricts airflow, which can lead to an overly rich fuel mixture. This means the engine has to work harder to draw in enough air, resulting in inefficient combustion and decreased performance. By keeping the air filter clean or replacing it when necessary, you help maintain optimal airflow to the engine, thus improving fuel efficiency and overall operation.

While other options involve maintenance tasks that are important for the engine's health, they do not have the same direct impact on fuel efficiency as maintaining the air filter does.