Piston Kit (0.50mm Oversize) – Fits Yamaha 2-Stroke 48/55/75/85 HP (Replaces 688-11636-03)
Piston Kit (0.50mm Oversize) – Fits Yamaha 2-Stroke 48/55/75/85 HP (Replaces 688-11636-03) is backordered and will ship as soon as it is back in stock.
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Worry-free returns
Worry-free returns
You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).
You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).
If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.
Delivery and Shipping
Delivery and Shipping
Free standard shipping on all orders under 1 KG
Product Details
This aftermarket Piston Kit (0.50mm Oversize) is designed for Yamaha 2-Stroke outboard motors ranging from 48 HP to 85 HP, manufactured between 1993 and 2005. It specifically fits a range of E48, 55B/BM/BET, E55, E75, and 85A series engines that require a cylinder bore of 82.1 mm.
It serves as a direct replacement for Yamaha OEM part numbers 688-11636-03 and 688-11635-03.
- Engineered for rebuilds and repairs on 2-stroke outboard engines.
- Machined from a durable aluminum alloy for reliable performance.
- Kit includes the piston, rings, wrist pin, and circlips for a complete installation.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Notes |
|---|---|---|
| Yamaha | 688-11636-03 | Primary Replacement |
| Yamaha | 688-11635-03 | Interchangeable |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
This piston kit is compatible with specific Yamaha outboard models. Ensure your engine's model and year are listed for correct fitment.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Yamaha | E48CMHS | 48 | 2-Stroke | 2003 | 688-11636-03 | |
| Yamaha | 55B/BM/BET | 55 | 2-Stroke | 1993–2002 | 688-11636-03 | |
| Yamaha | E55CMH | 55 | 2-Stroke | 2003–2005 | 688-11636-03 | |
| Yamaha | E75B | 75 | 2-Stroke | 2000 | 688-11636-03 | |
| Yamaha | 85A/AET/AED | 85 | 2-Stroke | 2000–2003 | 688-11636-03 |
Technical Specs
- Product Type
- Piston Kit (0.50mm Oversize)
- Application
- 2-Stroke Outboard Engines
- Bore Size
- 82.1 mm (0.50 mm oversize)
- Material
- Aluminum Alloy
- OEM Part Number
- 688-11636-03 (Yamaha)
What’s in the Box
- 1 x Piston (Replaces 688-11636-03)
- 2 x Piston Rings
- 1 x Piston Pin
- 2 x Circlips
Installation Notes
- Perform installation in a clean, well-lit workshop. Ensure you have your engine's service manual for reference.
- Disconnect the battery and fuel supply before beginning work on the engine.
- Carefully remove the cylinder head, gaskets, and existing piston assembly. Keep components organized.
- Measure the cylinder bore to confirm it matches the 82.1 mm oversize specification. Hone the cylinder walls if required.
- Fit the new rings onto the piston, ensuring the end gaps are correctly oriented and meet service manual specifications.
- Lubricate the piston, rings, and cylinder walls with 2-stroke engine oil before installing the new assembly with the wrist pin and circlips.
- Reassemble the engine using new gaskets and torque all fasteners to the manufacturer's specified values.
- After reassembly, perform a compression test to verify proper installation.
Troubleshooting & FAQ
How do I know if this 0.50mm oversize piston is right for my engine?
This oversize piston is intended for engine blocks where the cylinder has been machined (bored) 0.50mm larger than its standard diameter to correct for wear or damage. You must measure your cylinder's bore to confirm it is 82.1 mm before purchasing.
What are the signs of a failing piston?
Common symptoms of piston failure include significant loss of engine power, a drop in compression, audible knocking or rattling sounds from the engine, increased oil consumption, and excessive blue or white smoke from the exhaust.
Do the included piston rings need to be gapped?
Yes. It is critical to measure and set the end gap for the new piston rings according to your specific engine's service manual. Incorrect ring gap can lead to poor performance or catastrophic engine damage.
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.
Payment & Security
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