Piston Set STD – Fits Yamaha 2-Stroke 48/55/75/85/90HP Outboards (Replaces 688-11631-03-94)
Piston Set STD – Fits Yamaha 2-Stroke 48/55/75/85/90HP 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 aftermarket Piston Set STD – Fits Yamaha 2-Stroke 48/55/75/85/90HP Outboards (Replaces 688-11631-03-94) is designed for a wide range of Yamaha 2-Stroke outboards (48HP, 55HP, 75HP, 85HP, 90HP) from 1993 to 2006, along with Parsun T85 and compatible models. It serves as a direct-fit replacement for standard 82mm bore engines, ensuring reliable performance during engine rebuilds.
It directly replaces Yamaha OEM part numbers 688-11631-03-94, 688-11631-00, 688-11631-A0, 688-11631-02-95, 688-11631-02-96, 6H1-11631-01-96, and 6H1-11631-03-95.
- Engineered for gasoline-fueled 2-stroke outboard motors.
- Intended for engine rebuilds and cylinder servicing.
- Complete set includes the piston, rings, circlips, and wrist pin.
Part Number Matrix
Use this matrix to confirm equivalent references across OEM and aftermarket.
| Brand | Part Number |
|---|---|
| Yamaha | 688-11631-03-94 |
| Yamaha | 688-11631-00 |
| Yamaha | 688-11631-A0 |
| Yamaha | 688-11631-02-95 |
| Yamaha | 688-11631-02-96 |
| Yamaha | 6H1-11631-01-96 |
| Yamaha | 6H1-11631-03-95 |
Engine & Model Compatibility
Confirm your engine model/year in the table below.
For Yamaha models, verify that your model code and year align with the chart. For Parsun, this part is compatible with select T85 models.
| Brand | Model | Rated HP | Stroke | Years | OEM Part No. | Notes |
|---|---|---|---|---|---|---|
| Yamaha | C55ELRR, C55TLRR | 55 | 2-Stroke | 1993 | 688-11631-03-94 | |
| Yamaha | C85TLRR | 85 | 2-Stroke | 1993 | 688-11631-03-94 | |
| Yamaha | 90TJRS, 90TLRS | 90 | 2-Stroke | 1994 | 688-11631-03-94 | |
| Yamaha | C55ELRS, C55TLRS | 55 | 2-Stroke | 1994 | 688-11631-03-94 | |
| Yamaha | C75TLRS | 75 | 2-Stroke | 1994 | 688-11631-03-94 | |
| Yamaha | C85TLRS | 85 | 2-Stroke | 1994 | 688-11631-03-94 | |
| Yamaha | 90TLRT | 90 | 2-Stroke | 1995 | 688-11631-03-94 | |
| Yamaha | C55ELRT, C55TLRT | 55 | 2-Stroke | 1995 | 688-11631-03-94 | |
| Yamaha | C75TLRT | 75 | 2-Stroke | 1995 | 688-11631-03-94 | |
| Yamaha | C85TLRT | 85 | 2-Stroke | 1995 | 688-11631-03-94 | |
| Yamaha | E48MLHT | 48 | 2-Stroke | 1995 | 688-11631-03-94 | |
| Yamaha | E75MLHT | 75 | 2-Stroke | 1995 | 688-11631-03-94 | |
| Yamaha | 90TLRU | 90 | 2-Stroke | 1996 | 688-11631-03-94 | |
| Yamaha | C75TLRU | 75 | 2-Stroke | 1996 | 688-11631-03-94 | |
| Yamaha | C85TLRU | 85 | 2-Stroke | 1996 | 688-11631-03-94 | |
| Yamaha | E75MLHU | 75 | 2-Stroke | 1996 | 688-11631-03-94 | |
| Yamaha | P75TLHU | 75 | 2-Stroke | 1996 | 688-11631-03-94 | |
| Yamaha | 90TLRV | 90 | 2-Stroke | 1997 | 688-11631-03-94 | |
| Yamaha | C80TLRV | 80 | 2-Stroke | 1997 | 688-11631-03-94 | |
| Yamaha | C90TLRV | 90 | 2-Stroke | 1997 | 688-11631-03-94 | |
| Yamaha | E48MLHV | 48 | 2-Stroke | 1997 | 688-11631-03-94 | |
| Yamaha | E75MLHV | 75 | 2-Stroke | 1997 | 688-11631-03-94 | |
| Yamaha | P75TLHV | 75 | 2-Stroke | 1997 | 688-11631-03-94 | |
| Yamaha | 90TLRW, B90TLRW | 90 | 2-Stroke | 1998 | 688-11631-03-94 | |
| Yamaha | C75TLRW | 75 | 2-Stroke | 1998 | 688-11631-03-94 | |
| Yamaha | C90TLRW | 90 | 2-Stroke | 1998 | 688-11631-03-94 | |
| Yamaha | E48MLHW | 48 | 2-Stroke | 1998 | 688-11631-03-94 | |
| Yamaha | E75MLHW | 75 | 2-Stroke | 1998 | 688-11631-03-94 | |
| Yamaha | P75TLHW | 75 | 2-Stroke | 1998 | 688-11631-03-94 | |
| Yamaha | 90TLRX, B90TLRX | 90 | 2-Stroke | 1999 | 688-11631-03-94 | |
| Yamaha | C75TLRX | 75 | 2-Stroke | 1999 | 688-11631-03-94 | |
| Yamaha | C90TLRX | 90 | 2-Stroke | 1999 | 688-11631-03-94 | |
| Yamaha | E48MLHX | 48 | 2-Stroke | 1999 | 688-11631-03-94 | |
| Yamaha | E75MLHX | 75 | 2-Stroke | 1999 | 688-11631-03-94 | |
| Yamaha | P75TLHX | 75 | 2-Stroke | 1999 | 688-11631-03-94 | |
| Yamaha | 90TLRY, C90TLRY | 90 | 2-Stroke | 2000 | 688-11631-03-94 | |
| Yamaha | E48MHY, E48MLHY | 48 | 2-Stroke | 2000 | 688-11631-03-94 | |
| Yamaha | E75MLHY | 75 | 2-Stroke | 2000 | 688-11631-03-94 | |
| Yamaha | 90TJRZ, 90TLRZ, C90TLRZ | 90 | 2-Stroke | 2001 | 688-11631-03-94 | |
| Yamaha | 90TLRA | 90 | 2-Stroke | 2002 | 688-11631-03-94 | |
| Yamaha | 90TLRB | 90 | 2-Stroke | 2003 | 688-11631-03-94 | |
| Yamaha | 90TLRC | 90 | 2-Stroke | 2004 | 688-11631-03-94 | |
| Yamaha | 90TLRD | 90 | 2-Stroke | 2005 | 688-11631-03-94 | |
| Yamaha | 90TLR | 90 | 2-Stroke | 2006 and Later | 688-11631-03-94 | |
| Yamaha | E48C/CMH, 55B/BM/BET | 48, 55 | 2-Stroke | 688-11631-03-94 | Part of block/crankshaft assembly | |
| Yamaha | E55C/CMH, 55ED, 55ET | 55 | 2-Stroke | 688-11631-03-94 | Part of block/crankshaft assembly | |
| Yamaha | 75A/AED/AET, 75EHD | 75 | 2-Stroke | 688-11631-03-94 | Part of crankshaft assembly | |
| Yamaha | 85A/AED/AED-TUNA/AET/AEHD | 85 | 2-Stroke | 688-11631-03-94 | Part of crankshaft assembly | |
| Parsun | T85 | 85 | 2-Stroke | Compatible with Yamaha 688-11631-03-94 |
Technical Specs
- Product Type
- Piston Set
- Fitment
- Yamaha & Parsun 2-Stroke Outboards
- Installation
- Engine Rebuild
- Fuel Type
- Gasoline (2-Stroke)
- Housing Material
- Aluminum
- Bore Size
- 82mm Standard Bore
- Product Dimensions
- 8.5cm L x 8.5cm W x 9.0cm H
What’s in the Box
- 1 x Piston (688-11631-03-94)
- 2 x Piston Ring (Replaces 688-11603-00)
- 2 x Circlip (688-11634-00)
- 1 x Piston Pin (663-11633-00)
Installation Notes
- Consult your engine’s official service manual before starting work.
- Disconnect the battery and safely relieve fuel system pressure.
- Remove the powerhead and disassemble the cylinder block to access the old pistons.
- Carefully inspect cylinder walls for scoring or wear. Hone or bore if necessary.
- Install the new piston rings onto the piston, ensuring correct orientation.
- Use a ring compressor to gently install the piston and pin assembly into the cylinder.
- Verify all clearances and torque all fasteners to the manufacturer's specifications.
- Reassemble the engine, replace gaskets, and perform a leak-down test before starting.
Troubleshooting & FAQ
How do I know if my piston needs replacement?
Common signs of a failing piston include loss of compression, excessive smoke from the exhaust, a knocking sound from the engine, or metal shavings found in the engine oil. A cylinder compression test is the most reliable way to diagnose piston or ring issues.
Is this the correct size for my engine?
This is a standard (STD) 82mm bore piston set. If your engine cylinders have been bored oversize during a previous rebuild, you will need a corresponding oversize piston. Always measure your cylinder bore before ordering.
Do I need to break in the engine after installing new pistons?
Yes, a proper break-in period is critical. Follow your engine manufacturer's guidelines, which typically involve running the engine at varied, lower RPMs for the first several hours of operation and using a quality 2-stroke oil.
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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