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 proper alignment in systems where timing and rotational accuracy are critical. Always confirm correct sizing and placement before installation.

FAQ

Q: What are the early signs of a failing woodruff key?
A: You may notice slight timing issues, rough idle, or inconsistent engine performance.

Q: Can I replace this without removing major components?
A: Usually not—you’ll typically need access by removing the flywheel or related parts.

Q: Should I replace it even if it looks okay?
A: If there’s any doubt or visible wear, it’s safer to replace it while you’re in there.

Q: How should it fit once installed?
A: It should sit snug and flush in the keyway without rocking or sticking up unevenly.

Q: What causes these keys to fail most often?
A: Improper torque, sudden impact, or components slipping out of alignment are common causes.

• Supersessions
  90280-04M02-00