Yamaha - Woodruff Key Flywheel & Shaft Alignment 90280-04M04-00. Overview. This woodruff key is one of those parts that keeps everything lined up without drawing attention to itself. It holds your flywheel or gear in the exact position it needs to stay in so timing doesn't shift under load. I've seen engines run rough or lose timing completely from a key that was just slightly worn. It's a small piece, but it's doing critical work every time that motor is spinning.. Key Features. Precise Alignment Control - Keeps rotating components properly indexed for accurate engine timing.. Secure Anti-Slip Fit - Prevents movement between shaft and connected parts under load.. Durable Metal Construction - Built to handle engine torque and repeated use.. Yamaha-Specific Fit - Matches factory keyway dimensions for a clean and reliable install.. Engine & Boat Compatibility. Used across a variety of Yamaha outboards in flywheel, crankshaft, and other keyed shaft applications. Essential for maintaining