Piston Kit – Fits Yamaha 75-90HP 2-Stroke Outboards (Replaces 6H1-11631-03-95)
Piston Kit – Fits Yamaha 75-90HP 2-Stroke Outboards (Replaces 6H1-11631-03-95) 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 – Fits Yamaha 75-90HP 2-Stroke Outboards is designed for a wide range of Yamaha engines, including 55HP, 75HP, 85HP, and 90HP models manufactured between 1984 and 2013. It provides a reliable solution for engine rebuilds, matching standard bore specifications.
It serves as a direct replacement for Yamaha part numbers 6H1-11631-03-95 and 688-11631-03-94, and is interchangeable with Wiseco WIS3131 for standard bore applications.
- Installation is typically performed as part of a comprehensive engine rebuild.
- The complete kit includes a piston, ring set, wrist pin, and two pin clips.
- Engineered for a standard bore size of 82mm (3.228").
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number | Notes |
|---|---|---|
| Yamaha | 6H1-11631-03-95 | |
| Yamaha | 688-11631-03-94 | |
| Wiseco | WIS3131 | STD bore |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
Compatibility for Yamaha outboards is detailed below.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Yamaha | 55B | 55 | 2-Stroke | 1992–1996 | 6H1-11631-03-95 | |
| Yamaha | 75TLRB | 75 | 2-Stroke | 2003 | 6H1-11631-03-95 | |
| Yamaha | 75CETO | 75 | 2-Stroke | 2004–2013 | 6H1-11631-03-95 | |
| Yamaha | 75AE/T/M/HD | 75 | 2-Stroke | 1995 | 6H1-11631-03-95 | |
| Yamaha | 85HP | 85 | 2-Stroke | 1992–1993 | 688-11631-03-94 | |
| Yamaha | 90HP | 90 | 2-Stroke | 1984–2009 | 688-11631-03-94 |
Technical Specs
- Product Type
- Piston Kit
- Installation
- Engine Rebuild
- Bore Size
- 82mm STD (3.228")
- Ring Set
- Included
- Piston Pin
- Included
- Piston Pin Clips
- Included (2x)
- Housing Material
- Aluminum Alloy
- Dimensions
- 3.38" x 3.38" x 3.38"
- Other Technical Attributes
- Standard bore size
What’s in the Box
- 1 x Piston Kit (6H1-11631-03-95)
- 1 x Piston Pin
- 2 x Piston Pin Clips
- 1 x Ring Set (2 rings)
Installation Notes
- Disconnect the battery and safely secure the engine before beginning work.
- Drain all necessary fluids, such as fuel and oil, from the engine.
- Remove the powerhead cover, cylinder head, and any other components needed to access the piston.
- Carefully extract the old piston pin, piston, and rings from the connecting rod.
- Thoroughly clean the cylinder walls and inspect for any scoring, wear, or damage. Confirm the bore is within spec for a standard-size piston.
- Install the new piston rings onto the new piston, ensuring they are oriented correctly per service manual guidelines.
- Generously lubricate the new piston, rings, pin, and cylinder wall with 2-stroke engine oil.
- Using a ring compressor tool, carefully guide the new piston assembly into the cylinder.
- Reassemble all engine components in the reverse order of disassembly, torquing all fasteners to the manufacturer’s specifications.
- Refill engine fluids, reconnect the battery, and follow the recommended engine break-in procedure.
Troubleshooting & FAQ
How do I know if this piston kit will fit my engine?
This kit is for standard 82mm bore Yamaha 2-stroke outboards (55-90HP). Always verify your engine model and year against the compatibility chart and measure your cylinder bore before ordering. Using the wrong size can cause catastrophic engine failure.
Is this a standard size or oversize piston?
This is a standard (STD) bore 82mm piston kit. Oversize versions (e.g., 0.25mm, 0.50mm) are sold separately and are necessary only if your cylinder has been machined (bored out) to a larger diameter.
What are the signs of a failing piston?
Common signs include significant loss of compression, excessive blue or white smoke from the exhaust, a knocking or rattling sound from inside the engine, and a noticeable drop in performance and power.
Does this kit include everything I need for one cylinder?
Yes, this kit contains one piston, one set of rings, one piston pin, and two pin clips, which is a complete assembly for one cylinder.
What is the recommended replacement interval for a piston?
Piston replacement is not a routine maintenance item. It is typically performed during a complete engine rebuild, the timing of which is determined by engine hours, operating conditions, and overall mechanical health.
Do I need special tools for installation?
Yes, professional installation is strongly advised. Specialized tools such as a torque wrench, piston ring compressor, and potentially a cylinder hone are required to ensure proper installation, sealing, and long-term engine performance.
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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