Piston Kit STD (82mm) – Fits Yamaha 48/55/75/85HP 2-Stroke Outboards (Replaces 688-11631-03-94)
Piston Kit STD (82mm) – Fits Yamaha 48/55/75/85HP 2-Stroke Outboards (Replaces 688-11631-03-94) 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 is a standard bore Piston Kit STD (82mm) – Fits Yamaha 48/55/75/85HP 2-Stroke Outboards (Replaces 688-11631-03-94). It is designed for various Yamaha 2-stroke outboard models, including 48HP, 55HP, 75HP, and 85HP engines manufactured between 1993 and 2005.
It serves as a direct replacement for Yamaha part numbers 688-11631-03-94, 688-11631-03-00, 6H1-11631-03-00, and 688-11631-03.
- Intended for professional engine rebuilds and repairs.
- Made from durable aluminum alloy for reliable performance.
- Kit includes the piston, rings, pin, and clips for a complete installation.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Yamaha | 688-11631-03-94 |
| Yamaha | 688-11631-03-00 |
| Yamaha | 6H1-11631-03-00 |
| Yamaha | 688-11631-03 |
| Yamaha | 688116310394 |
| Yamaha | 688116310295 |
| Yamaha | 6H1116310196 |
| Yamaha | 6H1116310395 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Yamaha models, please verify your engine's specific model and year against this list to ensure proper fitment.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Yamaha | E48CMHS | 48 | 2-Stroke | 2003 | 688-11631-03-94 | |
| Yamaha | E48MLHT | 48 | 2-Stroke | 1995 | 688-11631-03-94 | |
| Yamaha | E48MLHU | 48 | 2-Stroke | 1996 | 688-11631-03-94 | |
| Yamaha | E48MLHW | 48 | 2-Stroke | 1998 | 688-11631-03-94 | |
| Yamaha | E48MLHX | 48 | 2-Stroke | 1999 | 688-11631-03-94 | |
| Yamaha | E48MLHY | 48 | 2-Stroke | 2000 | 688-11631-03-94 | |
| Yamaha | 55B/BM/BET | 55 | 2-Stroke | 1993–2002 | 688-11631-03-94 | |
| Yamaha | C55ELRR | 55 | 2-Stroke | 1993 | 688-11631-03-94 | |
| Yamaha | C55TLRR | 55 | 2-Stroke | 1993 | 688-11631-03-94 | |
| Yamaha | C55ELRS | 55 | 2-Stroke | 1994 | 688-11631-03-94 | |
| Yamaha | C55TLRS | 55 | 2-Stroke | 1994 | 688-11631-03-94 | |
| Yamaha | C55ELRT | 55 | 2-Stroke | 1995 | 688-11631-03-94 | |
| Yamaha | C55TLRT | 55 | 2-Stroke | 1995 | 688-11631-03-94 | |
| Yamaha | E55CMH | 55 | 2-Stroke | 2003–2005 | 688-11631-03-94 | |
| Yamaha | E75B | 75 | 2-Stroke | 2000 | 688-11631-03-94 | |
| Yamaha | C75TLRS | 75 | 2-Stroke | 1994 | 688-11631-03-94 | |
| Yamaha | C75TLRT | 75 | 2-Stroke | 1995 | 688-11631-03-94 | |
| Yamaha | E75MLHT | 75 | 2-Stroke | 1995 | 688-11631-03-94 | |
| Yamaha | E75MLHW | 75 | 2-Stroke | 1998 | 688-11631-03-94 | |
| Yamaha | E75MLHX | 75 | 2-Stroke | 1999 | 688-11631-03-94 | |
| Yamaha | E75MLHY | 75 | 2-Stroke | 2000 | 688-11631-03-94 | |
| Yamaha | 85A/AET/AED | 85 | 2-Stroke | 2000–2003 | 688-11631-03-94 | |
| Yamaha | C85TLRR | 85 | 2-Stroke | 1993 | 688-11631-03-94 | |
| Yamaha | C85TLRS | 85 | 2-Stroke | 1994 | 688-11631-03-94 | |
| Yamaha | C85TLRT | 85 | 2-Stroke | 1995 | 688-11631-03-94 |
Technical Specs
- Product Type
- Piston Kit
- Installation
- Engine Rebuild/Repair
- Bore Size
- 82mm (Standard)
- Material
- Aluminum Alloy
- Product Dimensions
- Height: 8.5; Width: 8.5; Length: 8.5;
- Package Contents
- Piston, Piston Rings, Piston Pin, Retainer Clips
What’s in the Box
- 1 x Piston (Replaces 688-11631-03-94)
- 1 x Piston Rings Set
- 1 x Piston Pin
- 2 x Retainer Clips
Installation Notes
- Disconnect the battery and ensure the engine is cool. Drain engine oil and coolant.
- Remove the cylinder head and any components obstructing access to the pistons.
- Carefully inspect cylinder walls for scoring or damage. Hone the cylinder to the correct specification for the new piston rings.
- Align the piston rings on the new piston according to the manufacturer's guide, ensuring ring gaps are staggered.
- Lubricate the piston, rings, and cylinder wall with fresh engine oil.
- Using a piston ring compressor, gently install the piston into the cylinder, ensuring the correct orientation.
- Attach the connecting rod to the crankshaft, torquing bolts to the specified values.
- Reassemble the engine in reverse order of disassembly, using new gaskets as needed.
- Refill engine oil and coolant. Reconnect the battery.
- Follow a proper engine break-in procedure before operating at full load.
Troubleshooting & FAQ
How do I know if this piston kit fits my engine?
The best way to confirm fitment is to check your engine's model number and year against the compatibility table provided on this page. You should also verify that your engine requires the standard 82mm bore size.
What are the signs of a failing piston?
Common signs include loss of compression, increased oil consumption, blue smoke from the exhaust, and a knocking or rattling sound from the engine. A diagnostic compression test can help confirm the issue.
Should I replace all pistons at the same time?
For optimal engine balance and performance, it is highly recommended to replace all pistons as a set, especially on high-hour engines. Replacing only one can lead to imbalances and premature wear on other components.
Is honing the cylinder necessary for new piston rings?
Yes, honing the cylinder bore is critical. It creates a cross-hatch pattern that helps the new piston rings seat properly, ensuring a good seal for optimal compression and oil control.
What is the difference between this standard (STD) kit and an oversize kit?
A standard (STD) kit is for cylinders that are within factory specifications. Oversize pistons are used when a cylinder has been bored out to correct for wear or damage. This kit is for standard 82mm bores only.
Is this an OEM or aftermarket part?
This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials. All our parts are manufactured in an ISO 9002 facility and are batch-inspected for quality and consistency.
What are the shipping speed and cost?
We ship worldwide quickly—typical transit time is 5–15 days. Standard shipping is free for most regions, with expedited options available at checkout where applicable.
What is the warranty and return policy?
This product is covered by a 1-year warranty against manufacturing defects under normal use. If you encounter any issues, please contact our support team with your order details. Returns are accepted within our standard window, provided the item is unused and in its original condition. See our full policy page or reach out for instructions.
Safety & Important Info
- Verify images and specifications against your original part before purchase. If anything differs—even if your model appears compatible—do not purchase.
- This is an aftermarket replacement part, not an original equipment manufacturer (OEM) component.
- Professional installation is strongly recommended for safety and to ensure proper performance.
About Sea Sierra
- Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and rigorously tested for real-world conditions.
- Fast Global Fulfillment — We offer free standard delivery to most regions, with typical transit times of 5–15 days.
- Manufacturer-Direct Value — By working directly with manufacturers, we provide fair pricing without compromising on materials or quality control.
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