Piston Ring Kit 0.50mm (Oversize) – Fits Yamaha 40HP 2-Stroke (Replaces 66T-11605-00, 682-11610-21)
Piston Ring Kit 0.50mm (Oversize) – Fits Yamaha 40HP 2-Stroke (Replaces 66T-11605-00, 682-11610-21) is backordered and will ship as soon as it is back in stock.
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Delivery and Shipping
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Piston Ring Kit 0.50mm (Oversize) – Fits Yamaha 40HP 2-Stroke (Repl...
Product Details
This is a Piston Ring Kit 0.50mm (Oversize) designed for Yamaha 40HP 2-Stroke outboard engines manufactured between 2002 and 2013, including models E40X, 40XMH, E40XMH, 40XW, E40XW, 40XWT and E40XWT. It's engineered for cylinders that have been bored 0.50mm over the standard size during an engine rebuild.
This kit serves as a direct replacement for Yamaha OEM part numbers 66T-11605-00 and 682-11610-21, providing a reliable alternative for engine maintenance and repair.
- Engineered for a precise fit in 0.50mm oversize bored cylinders.
- Designed specifically for 2-stroke gasoline marine engines.
- Installation is cylinder-specific; one kit is required per piston.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Yamaha | 66T-11605-00 |
| Yamaha | 682-11610-21 |
| Aftermarket | REC682-11610-21 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. |
|---|---|---|---|---|---|
| Yamaha | E40X | 40 | 2-Stroke | 2002–2013 | 66T-11605-00/682-11610-21 |
| Yamaha | 40XMH | 40 | 2-Stroke | 2003–2013 | 66T-11605-00/682-11610-21 |
| Yamaha | 40XW | 40 | 2-Stroke | 2003–2013 | 66T-11605-00/682-11610-21 |
| Yamaha | E40XMH | 40 | 2-Stroke | 2002–2013 | 66T-11605-00/682-11610-21 |
| Yamaha | E40XW | 40 | 2-Stroke | 2002–2013 | 66T-11605-00/682-11610-21 |
| Yamaha | 40XWT | 40 | 2-Stroke | 2003–2013 | 66T-11605-00/682-11610-21 |
| Yamaha | E40XWT | 40 | 2-Stroke | 2002–2013 | 66T-11605-00/682-11610-21 |
Technical Specs
- Product Type
- Piston Ring Kit (0.50mm Oversize)
- Installation
- Engine cylinder-specific
- Fuel Type
- Gasoline (2-stroke)
- Dimensions
- 80.5mm (3.17") bore diameter (0.50mm oversize)
- Warranty
- 1 year (aftermarket)
- Other Technical Attributes
- 0.50mm oversize piston rings for Yamaha 40HP 2-stroke engines
What’s in the Box
- 1 x Piston Ring Kit 0.50mm oversize (replaces 66T-11605-00/682-11610-21)
Installation Notes
- Ensure the engine is off, cool, and the battery is disconnected before starting.
- Remove the cylinder head and other components as needed to access the piston.
- Use a piston ring expander tool to carefully remove the old rings from the piston.
- Thoroughly clean all carbon deposits from the piston ring grooves.
- Install the new rings onto the piston in the correct order and orientation as specified by the service manual.
- Generously lubricate the new rings, piston, and cylinder wall with fresh 2-stroke engine oil.
- Use a piston ring compressor tool to gently guide the piston back into the cylinder without damaging the rings.
- Reassemble all engine components in reverse order, torquing all fasteners to the manufacturer's specifications.
Troubleshooting & FAQ
When should I use 0.50mm oversize rings?
Oversize piston rings are required when an engine cylinder has been bored or honed 0.50mm larger than its standard diameter, typically during an engine rebuild to correct for wear or tapering.
Will these rings fit a standard, non-bored cylinder?
No, these rings are specifically designed for an oversized bore. Installing them in a standard cylinder will result in improper fit, ring damage, and engine failure.
What are the signs of failing piston rings?
Common symptoms include a noticeable loss of engine power, increased oil consumption, and excessive blue or white smoke from the exhaust, which indicates oil is bypassing the rings and burning in the combustion chamber.
How many pistons does one kit service?
This kit contains all the necessary rings to service a single piston. If you are rebuilding multiple cylinders, you must purchase one kit per piston.
Are special tools required for installation?
Yes, professional installation is recommended. Essential tools include a piston ring expander for safe ring handling and a piston ring compressor to ensure the piston and rings are installed into the cylinder correctly.
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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