Yamaha 787-11631-04-99 – Piston (STD)

Yamaha 787-11631-04-99 – Piston (STD)

Restore full engine compression and peak performance with the Yamaha 787-11631-04-99 – Piston (std). This standard-size OEM piston is engineered to deliver precise fit, proper balance, and consistent combustion inside your Yamaha outboard motor. Whether you're rebuilding a worn cylinder or replacing a damaged piston, this genuine part ensures durability and optimal engine function under marine operating conditions.

Key Features

Genuine Yamaha OEM Part – Designed to Yamaha factory standards for marine-grade performance

Standard Size Fitment – Perfect for engines with cylinders still within original tolerance

Optimized for Performance – Supports consistent combustion and power delivery

High-Quality Construction – Built from heat-resistant materials for long-term reliability

Ideal Use Cases

This piston is ideal for engine rebuilds, cylinder repairs, or replacing a damaged piston that’s affecting compression, oil control, or power. It’s a critical component when restoring a Yamaha outboard to like-new condition and performance standards.

Why OEM Pistons Matter

The piston is central to your engine’s combustion process. Even slight imperfections in shape, size, or material quality can lead to power loss, oil burn, or premature failure. The Yamaha 787-11631-04-99 – Piston (std) offers the reliability and exacting tolerances needed to maintain strong compression, efficient combustion, and smooth engine operation.

Frequently Asked Questions

What does the Yamaha 787-11631-04-99 – Piston (std) do?

This piston compresses the air-fuel mixture inside the cylinder, driving the power stroke of your Yamaha outboard’s engine.

How do I know if I need a standard piston or an oversized one?

Use a bore gauge or have a technician inspect your cylinder walls. If your cylinder is still within factory specs, a standard piston like this is the correct choice.

Should I replace other components when installing a new piston?

Yes. It’s recommended to replace piston rings and inspect the connecting rod, wrist pin, and bearings to ensure a complete and reliable rebuild.