Yamaha - Woodruff Key Flywheel & Shaft Alignment 90280-04M08-00. Overview. This woodruff key is one of those small parts that keeps everything in sync without much attention. It locks your flywheel or gear in place so timing stays right where it should be. I've seen engines run rough or lose timing just because this piece was slightly worn or out of place. It's simple, but it's a critical part of keeping your motor running smooth.. Key Features. Precise Timing Alignment - Keeps rotating components properly indexed for consistent engine performance.. Secure Shaft Engagement - Prevents slipping between the shaft and connected parts under load.. Durable Metal Construction - Built to handle engine torque and repeated use.. Factory-Exact Fit - Matches Yamaha keyway dimensions for proper seating and reliability.. Engine & Boat Compatibility. Used across a range of Yamaha outboards in flywheel, crankshaft, and other keyed shaft applications. Supports systems where accurate alignment is essent