Yamaha Piston Kit (0.25mm Oversize) – Fits Yamaha 40HP 2-Stroke (Replaces 6F6-11635-00)
Yamaha Piston Kit (0.25mm Oversize) – Fits Yamaha 40HP 2-Stroke (Replaces 6F6-11635-00) is backordered and will ship as soon as it is back in stock.
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Yamaha Piston Kit (0.25mm Oversize) – Fits Yamaha 40HP 2-Stroke (Re...
Product Details
This is a Yamaha Piston Kit (0.25mm Oversize) designed for Yamaha 40HP 2-Stroke outboard engines including models E40GMH, E40JMH, E40JWH, 40GWH, and 40JWH from years 2003–2004. It is manufactured from a high-strength aluminum alloy for durability and performance in marine environments.
This kit serves as a direct replacement for Yamaha OEM part number 6F6-11635-00.
- Specifically intended for cylinder reboring and repair applications requiring a 0.25mm oversize.
- This is an internal engine component requiring proper installation.
- The package contains a complete piston assembly with rings, wrist pin, and circlips.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Yamaha | 6F6-11635-00 |
| Yamaha | 6F61163500 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Yamaha | E40GMH | 40 | 2-Stroke | 2003 | 6F6-11635-00 | 0.25mm oversize |
| Yamaha | E40JMH | 40 | 2-Stroke | 2003 | 6F6-11635-00 | 0.25mm oversize |
| Yamaha | E40JWH | 40 | 2-Stroke | 2003 | 6F6-11635-00 | 0.25mm oversize |
| Yamaha | 40GWH | 40 | 2-Stroke | 2003 | 6F6-11635-00 | 0.25mm oversize |
| Yamaha | 40JWH | 40 | 2-Stroke | 2003 | 6F6-11635-00 | 0.25mm oversize |
Technical Specs
- Product Type
- Piston Kit (0.25mm Oversize)
- Application
- 40HP 2-Stroke Outboard Engines
- Oversize
- 0.25mm
- Fuel Type
- Gasoline (Petrol)
- Material
- High-strength aluminum alloy
- Installation
- Internal Engine Component
- Dimensions
- 8.5 x 8.5 x 8.5 cm
- Weight
- 0.45 kg (0.99 lb)
- Other Technical Attributes
- For cylinder reboring/repair applications
What’s in the Box
- 1 x Piston
- 1 x Piston Ring Set
- 1 x Wrist Pin
- 2 x Circlips
Installation Notes
- Disconnect the battery and ensure the engine is cool before starting work.
- Remove the engine cowling and cylinder head cover.
- Carefully disassemble the cylinder head and相關 components to access the original piston.
- Remove the old piston by detaching the connecting rod and pushing it out of the cylinder.
- Inspect the cylinder for wear or damage. For this oversize kit, the cylinder must be professionally bored and honed to the correct new diameter.
- Install the new piston rings onto the oversize piston, ensuring correct orientation.
- Lubricate the new piston, rings, and cylinder wall with 2-stroke engine oil.
- Install the new piston assembly carefully into the cylinder using a ring compressor tool.
- Reconnect the connecting rod and torque all bolts to the manufacturer's specified values.
- Reassemble the cylinder head and all other components in reverse order of disassembly.
- Reconnect the battery, start the engine, and check for proper operation and any leaks.
Troubleshooting & FAQ
How do I know if I need an oversize piston?
An oversize piston is required when the engine cylinder is worn or scored beyond the service limits of the standard piston. A qualified marine mechanic must measure the cylinder bore to determine if reboring and an oversize piston are necessary for repair.
Why is this piston +0.25mm oversize?
The 0.25mm oversize dimension is a standard repair size. When a cylinder wall is damaged or worn, it can be bored out to a clean, uniform surface. This oversize piston is designed to match that newly bored cylinder diameter, restoring compression and performance.
Will this kit fit models outside the listed 2003-2004 years?
This kit is specifically confirmed for the 2003–2004 models listed. While it may fit other years with the same engine block configuration, we can only guarantee compatibility for the models specified in the table. Please verify your OEM part number before ordering.
What are the signs of a failing piston?
Common symptoms include loss of compression, reduced engine power, excessive blue or white smoke from the exhaust, unusual rattling or knocking sounds from the engine, and increased oil consumption.
OEM vs. Aftermarket?
This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.
Shipping speed & cost?
We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.
Warranty & returns?
Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.
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.
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