Order code: RKC051. Sinnis: Terrain T125 ZS125-86(T125). Zongshen: ZS125-39. Taro: TR125-3. Mutt: Stravaig 125cc STRAVAIG. Mitt: MITT 125 GP 2 MITT125GP2. The rocker cover, also known as the valve cover, is a component that sits atop the engine’s cylinder head, covering the rocker arms and valvetrain.