Mercury - Timing Belt 15-20 HP Four-Stroke Series Reinforced Marine Composite 895120002. Overview. There's something reassuring about a small outboard that runs clean and steady. You hear it in the smooth thrum at idle, that soft heartbeat of a motor that's perfectly in sync. When you're running a fifteen or twenty horsepower Mercury, the timing belt becomes one of those quiet heroes-working behind the scenes to keep everything aligned and predictable. A dependable belt gives you the comfort of