Piston Kit – Fits Yamaha 4HP/5HP Outboard Motors (Replaces 6E0-11631-00-98, 761-8256M)

Product Details

This aftermarket Piston Kit – Fits Yamaha 4HP/5HP Outboard Motors (Replaces 6E0-11631-00-98, 761-8256M) is engineered for Yamaha 4HP & 5HP 2-stroke outboard motors (1984–1999) and Mercury/Mariner 4HP 2-stroke models with serial numbers 6E0-001011 and up.

It serves as a direct replacement, providing an interchange for Yamaha part numbers 6E0-11631-00-98, 6E0-11631-00-97, 6E0-11631-00-96, and 6E0-11631-00-99, as well as Mercury/Mariner 761-8256M.

• Engineered for direct-fit installation.
• Constructed from high-strength aluminum alloy for durability.
• Kit includes piston, rings, pin, and circlips for a complete top-end service.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Engine & Model Compatibility

Confirm your engine model/year in the table below.

For Yamaha owners: This kit is compatible with a wide range of 4HP and 5HP 2-stroke models manufactured between 1984 and 1999.

For Mercury/Mariner owners: This kit fits 4HP 2-stroke models with serial numbers 6E0-001011 and higher.

Technical Specs

Product Type

Piston Kit

Installation

Direct replacement

Piston Diameter

50mm (Standard)

Piston Height

57.5mm

Wrist Pin Diameter

12mm

Housing Material

Aluminum alloy

Fuel Type

Gasoline

What’s in the Box

• 1 x Piston (Replaces 6E0-11631-00-98)
• 3 x Piston Rings (Replaces 6G1-11610-00)
• 2 x Circlips (Replaces 93450-13022)
• 1 x Piston Pin (Replaces 6G1-11633-00)

Installation Notes

1. Ensure the engine is cool and disconnect the spark plug wire and battery for safety.
2. Drain the engine oil and coolant. Remove the engine cover and any interfering components.
3. Carefully remove the cylinder head and gasket. Rotate the crankshaft to bring the piston to a workable position.
4. Remove the old piston pin circlips and push out the piston pin to disconnect the piston from the connecting rod.
5. Thoroughly clean the cylinder walls and connecting rod surface, inspecting for any scoring or damage.
6. Install the new piston rings onto the new piston, ensuring correct orientation. Attach the new piston to the connecting rod with the new piston pin and secure it with new circlips.
7. Using a piston ring compressor, gently guide the piston assembly into the cylinder.
8. Reinstall the cylinder head with a new gasket, torquing bolts to manufacturer specifications. Reconnect all components and refill fluids.

Troubleshooting & FAQ

Safety & Important Info

• Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
• This is an aftermarket replacement, not an OEM component.
• Professional installation is recommended for safety and performance.

About Sea Sierra

• Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
• Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
• Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.