Yamaha - Woodruff Key - Flywheel & Shaft Alignment - 90280-05040-00

Overview

This woodruff key is one of those parts that does its job quietly, but you’ll know right away when it’s not right. It keeps your flywheel and shaft locked in proper position so timing stays consistent every time you run the motor. I’ve seen engines chase all kinds of issues that came down to a worn or slightly sheared key. It’s small, but it’s a critical piece for keeping everything running smooth and in sync.

Key Features

• Precise Timing Alignment – Keeps components indexed correctly to maintain proper engine timing.

• Secure Shaft Engagement – Prevents slipping between the shaft and connected parts under load.

• Heavy-Duty Metal Build – Designed to handle torque and continuous engine operation.

• Factory-Exact Fit – Matches Yamaha specifications for proper seating and performance.

Engine & Boat Compatibility

Used across many Yamaha outboards in flywheel, crankshaft, and other keyed shaft applications. Essential for maintaining correct alignment in systems where engine timing and rotational accuracy matter. Always confirm correct sizing and application before installation.

FAQ

Q: What happens if this woodruff key starts to fail?
A: You’ll usually notice timing issues, rough running, or the engine may not start.

Q: Can I install it without removing the flywheel?
A: In most cases, the flywheel or connected component will need to come off for access.

Q: Should the key sit completely flush in the slot?
A: Yes, it should sit snug and even—no rocking or sticking out unevenly.

Q: Is this part affected by saltwater exposure?
A: Over time, yes—corrosion can build up, so clean installs and maintenance are important.

Q: What’s a common mistake during installation?
A: Not seating it fully or forcing it into place, which can cause it to fail quickly once the engine runs.