90012-333-000 Tappet Adj Screw - Overview. The 90012-333-000 Tappet Adj Screw is a critical component in the valve train of Honda marine engine systems. It supports the camshaft and valve system by allowing precise adjustment of valve clearance, which is essential for maintaining optimal engine performance and longevity. This screw ensures smooth engine operation by fine-tuning the valve gap, preventing valve and rocker arm wear, and enabling efficient combustion.. Key Features. Genuine OEM Hond