New Yamaha 75–100HP 2-/4-Stroke (1984–2017) Replacement Lower Unit – Aftermarket | Standard Rotation | Fits 20″ & 25″ Shafts | 2.0 & 2.3 Gear Ratios | 3-Year Warranty
Original price was: $1,330.89.$1,199.00Current price is: $1,199.00.
New Yamaha 150–200HP 2/4-Stroke (1984–2024) Replacement Lower Unit | Aftermarket | Standard Rotation | Fits 20″ & 25″ Shafts | 3-Year Warranty
Original price was: $1,330.89.$1,199.00Current price is: $1,199.00.
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New Yamaha 115–130HP 2/4-Stroke (1984–2014) Replacement Lower Unit | Aftermarket | Standard Rotation | Fits 20″ & 25″ Shafts | 3-Year Warranty
Original price was: $1,330.89.$1,199.00Current price is: $1,199.00.
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
The SEI 90-405 Yamaha 115–130HP lower unit is a brand-new, high-quality aftermarket replacement designed for both 2-stroke and 4-stroke Yamaha outboard engines from 1984 to 2014. Built to OEM specifications, it provides smooth shifting, durable performance, and dependable reliability. Available in 20″ and 25″ shaft lengths, this standard rotation lower unit ensures a perfect fit for a wide range of Yamaha outboards.
Key Features
100% brand-new aftermarket Yamaha 115–130HP lower unit – no core return required
Designed for Yamaha 2-stroke and 4-stroke outboards (1984–2014)
Built for standard rotation (right-hand) applications
Gear ratios: 2:1 (2-Stroke) and 2.15:1 (F115 4-Stroke)
Painted black and can be repainted to match OEM finish
Manufactured with precision components for long-lasting performance
Protected by an industry-leading 3-year fault-free warranty
Specifications
| Feature | Details |
|---|---|
| Model | SEI 90-405 |
| Horsepower Range | 115HP–130HP |
| Engine Type | 2-Stroke & 4-Stroke |
| Rotation | Standard (Right-Hand) |
| Compatible Years | 1984–2014 |
| Shaft Lengths | 20″ & 25″ |
| Gear Ratios | 2:1 (2-Stroke), 2.15:1 (F115 4-Stroke) |
| Paint Color | Black (repaintable to match OEM) |
| Warranty | 3-Year |
| Brand | SEI (Sterndrive Engineering Inc.) |
Why Choose the Yamaha 115–130HP Aftermarket Lower Unit?
The Yamaha 115–130HP aftermarket lower unit from SEI offers the perfect combination of performance, reliability, and value. Each unit is built entirely from new components, not remanufactured or rebuilt parts, ensuring consistent strength and smooth operation.
Designed as a direct replacement for OEM Yamaha lower units, the SEI 90-405 meets or exceeds factory standards. It’s a cost-effective alternative that maintains the same precision fit, gear alignment, and overall quality expected from original Yamaha assemblies.
With its 3-year no-fault warranty, this lower unit provides peace of mind and unmatched protection. Whether replacing a damaged unit or upgrading for better reliability, this aftermarket Yamaha 115–130HP lower unit is the professional’s choice for lasting performance.
Frequently Asked Questions – Yamaha 115–130HP Replacement Lower Unit
1. Which Yamaha outboard models are compatible with the SEI 90-405 115–130HP lower unit?
The SEI 90-405 lower unit is engineered for Yamaha 115HP to 130HP outboards produced from 1984 to 2014, supporting both 2-stroke and 4-stroke engines. It fits standard rotation outboards and is available for 20″ (long) and 25″ (extra-long) shaft lengths. Specific compatibility includes popular 2-stroke and 4-stroke F115 models, but does not fit newer outboards outside the listed range.
2. What gear ratios are offered for this aftermarket lower unit, and how do I select the right one?
This SEI replacement lower unit is available in two gear ratios: 2:1 for standard Yamaha 2-stroke models, and 2.15:1 for the F115 4-stroke model. To ensure optimal performance and correct propeller speed, match the gear ratio to your outboard’s original specification as indicated in your owner’s manual or service documentation.
3. Is this lower unit new, rebuilt, or remanufactured?
The SEI 90-405 lower unit is 100% brand new, built from all-new components — not rebuilt, not remanufactured, and no core return is required. Each assembly is thoroughly pressure-tested for quality and comes pre-assembled with all critical internals, ensuring consistent durability from the moment of installation.
4. Does this lower unit come with a warranty, and what does it cover?
Yes, every SEI 90-405 Yamaha 115–130HP lower unit includes an industry-leading 3-Year Fault-Free Warranty. This comprehensive warranty covers defects in materials and workmanship as well as mechanical failures under normal use, providing peace of mind for recreational boaters and professionals alike.
5. What preparation is needed for installation, and is the unit painted?
The unit is shipped painted in black for corrosion resistance, and it can be repainted to match the factory Yamaha color. Before installation, fill the lower unit with the correct marine gear oil—units are shipped dry. Also, verify shaft length and gear ratio compatibility with your current outboard setup for seamless installation.
Explore More Yamaha Lower Units
Browse All Yamaha Lower Unit Categories — find compatible options for 40HP, 60HP, 115HP, 150HP, and more Yamaha outboards.
Additional information
| Weight | 85 lbs |
|---|---|
| Dimensions | 23 × 13 × 26 in |
| Ratio/Shaft |
2:1 Ratio / 20" Shaft / 2 Stroke / RH Rotation ,2:1 Ratio / 25" Shaft / 2 Stroke / RH Rotation ,2.15:1 Ratio / 20" Shaft / 4 Stroke / RH Rotation ,2.15:1 Ratio / 25" Shaft / 4 Stroke / RH Rotation |
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