New Yamaha F200–F300 4-Stroke (2014–2021) Replacement Lower Unit | Aftermarket | Standard Rotation | Fits 30″ Shaft | 1.75 Gear Ratio | 3-Year Warranty
Original price was: $1,921.90.$1,699.00Current price is: $1,699.00.
New Yamaha 250HP 4-Stroke (2005–2018) Counter-Rotation Replacement Lower Unit Aftermarket | Fits 25″ & 30″ Shafts | 2.00 Gear Ratio | 1-Year Warranty
Original price was: $1,921.90.$1,699.00Current price is: $1,699.00.
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New Yamaha 200–250HP 2/4-Stroke (1990–2019) Replacement Lower Unit | Aftermarket | Counter Rotation | Fits 25″ & 30″ Shafts | 3-Year Warranty
Original price was: $1,552.89.$1,399.00Current price is: $1,399.00.
Need help finding the right lower unit?
- Unsure about compatibility? Our team can verify the perfect fit for your Yamaha model.
- Call us at 888 868 7880 — we’re happy to guide you.
- Or fill out the form below in chatbox and we’ll respond quickly with the right match.
Description
Replace or upgrade your Yamaha outboard with this premium aftermarket counter-rotation lower unit designed for Yamaha 200HP, 225HP, and select 250HP V6 models (1990–2019).
Engineered for precision and durability, the SEI 90-428 lower unit fits both 2-stroke and 4-stroke Yamaha V6 engines and installs directly—no modifications required. Whether you run offshore or freshwater, this lower unit ensures smooth operation, long gear life, and dependable reverse performance.
It’s available in 25″ and 30″ shaft lengths with 1.81:1 (2-stroke) or 2.0:1 (4-stroke) gear ratios, built to OEM specs and backed by a 3-year, fault-free warranty for total peace of mind.
Key Highlights
Counter Rotation — perfect for twin-engine setups
Compatible with Yamaha V6 200-250HP outboards (1990–2019)
Direct-fit installation – no adjustments or modifications
Heavy-duty construction for saltwater and freshwater
Painted black (can be repainted to match your engine)
Long-lasting performance backed by a 3-year warranty
Specifications
| Feature | Details |
|---|---|
| Product Name | Yamaha V6 200–250HP Counter Rotation Lower Unit |
| Compatible Models | 2-Stroke & 4-Stroke V6 |
| Horsepower Range | 200HP / 225HP / Some 250HP |
| Years Supported | 1990–2019 |
| Rotation | Counter Rotation Only |
| Shaft Length | 25″ / 30″ |
| Gear Ratios | 1.81:1 (2-Stroke) / 2.0:1 (4-Stroke) |
| Condition | New – Aftermarket |
| Paint Finish | Black (Paintable to Match) |
| Warranty | 3 Years |
| Part Code / SKU | 90-428 |
| Installation | Direct Fit – No Modifications Required |
| Usage | Freshwater & Saltwater Compatible |
Why Choose the Yamaha 200–250HP Counter Rotation Lower Unit
Choosing the aftermarket Yamaha 200–250HP counter-rotation lower unit gives you OEM-level performance without the high price tag. It’s designed for long-term reliability, easy installation, and precise handling in twin-engine setups. With its 3-year warranty and strong build quality, it’s a smart investment for any serious boater or marine mechanic.
Frequently Asked Questions – Yamaha 200–250HP Counter Rotation Replacement Lower Unit
1. Which Yamaha outboard models does the SEI 90-428 counter rotation lower unit fit?
The SEI 90-428 fits most Yamaha 200HP and 225HP V6 2-stroke and 4-stroke outboards as well as select 250HP 76° V6 models manufactured between 1990 and 2019. It is designed specifically for counter rotation applications ideal for twin-engine boats.
2. What shaft lengths and gear ratios are available for this lower unit?
This unit is available in 25″ and 30″ shaft lengths. Gear ratios offered are 1.81:1 for 2-stroke engines and 2.0:1 for 4-stroke engines, matching OEM specifications for optimal performance and durability.
3. Is the SEI 90-428 lower unit new or rebuilt?
The SEI 90-428 is a brand-new aftermarket lower unit built to precise OEM standards. It offers fully assembled components with a heavy-duty design for both freshwater and saltwater use, backed by a 3-year fault-free warranty.
4. Does installation require any modifications or special parts?
Installation is a direct bolt-on fit that requires no modifications or adapters. It is designed for hassle-free replacement with the same exact fitment as original Yamaha counter-rotation models.
5. What warranty coverage is included with the SEI 90-428 lower unit?
SEI provides a comprehensive 3-year fault-free warranty covering defects in manufacturing and mechanical failures under normal recreational use, giving you confidence in the unit’s long-term reliability.
Looking for other models or gear ratios?
Browse all Yamaha Lower Units here — find compatible options for 40HP, 60HP, 115HP, 150HP, and more Yamaha outboards.
Additional information
| Weight | 90 lbs |
|---|---|
| Dimensions | 23 × 13 × 31 in |
| Degree/Motor/Length |
3.1L&3.2L/Two Stroke V6/25" Shaft/1.8 Ratio/Left Hand Rotation ,3.1L&3.2L/Two Stroke V6/30" Shaft/1.8 Ratio/Left Hand Rotation ,6 Cylinder/Four Stroke V6/25" Shaft/2.0 Ratio/Left Hand Rotation ,6 Cylinder/Four Stroke V6/30" Shaft/2.0 Ratio/Left Hand Rotation |
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