What measures can be implemented to prevent tampering?

Installing limiter caps or plugs is a highly effective measure to prevent tampering with small engines. These devices restrict access to essential adjustments and modifications that might be made to the engine's performance settings, such as fuel mixture or RPM levels. By securing the components in a way that they cannot be easily altered, these caps or plugs deter users from making unauthorized changes that could lead to non-compliance with performance standards or regulations.

Limiter caps are particularly valuable in environments where regulations for emissions and noise levels are stringent and where maintaining optimal performance as designed by the manufacturer is crucial. This mechanism promotes consistency and reliability in engine performance while also safeguarding the integrity of the engine’s design specifications.

On the other hand, the other choices do not primarily focus on preventing tampering. Using high-performance fuels may enhance engine performance but does not address tampering directly. Increasing engine size often affects the engine's capability but doesn't relate to controlling tampering. Limiting the engine's running time could be relevant in specific operational contexts but does not directly prevent users from modifying the engine itself.