New Yamaha 150–200HP 2/4-Stroke (1984–2024) Replacement Lower Unit | Aftermarket | Standard Rotation | Fits 20″ & 25″ Shafts | 3-Year Warranty image 0
New Yamaha 150–200HP 2/4-Stroke (1984–2024) Replacement Lower Unit | Aftermarket | Standard Rotation | Fits 20″ & 25″ Shafts | 3-Year Warranty image 1
New Yamaha 150–200HP 2/4-Stroke (1984–2024) Replacement Lower Unit | Aftermarket | Standard Rotation | Fits 20″ & 25″ Shafts | 3-Year Warranty image 2
New Yamaha 150–200HP 2/4-Stroke (1984–2024) Replacement Lower Unit | Aftermarket | Standard Rotation | Fits 20″ & 25″ Shafts | 3-Year Warranty image 3
New Yamaha 150–200HP 2/4-Stroke (1984–2024) Replacement Lower Unit | Aftermarket | Standard Rotation | Fits 20″ & 25″ Shafts | 3-Year Warranty image 0
New Yamaha 150–200HP 2/4-Stroke (1984–2024) Replacement Lower Unit | Aftermarket | Standard Rotation | Fits 20″ & 25″ Shafts | 3-Year Warranty image 1
New Yamaha 150–200HP 2/4-Stroke (1984–2024) Replacement Lower Unit | Aftermarket | Standard Rotation | Fits 20″ & 25″ Shafts | 3-Year Warranty image 2
New Yamaha 150–200HP 2/4-Stroke (1984–2024) Replacement Lower Unit | Aftermarket | Standard Rotation | Fits 20″ & 25″ Shafts | 3-Year Warranty image 3

New Yamaha 150–200HP 2/4-Stroke (1984–2024) Replacement Lower Unit | Aftermarket | Standard Rotation | Fits 20″ & 25″ Shafts | 3-Year Warranty

$1,199.00
$1,330.89
$1,199.00
(-10%)

MPN :

Availability: In stock
Product type: Lower Unit
Please hurry! Only 100 left in stock
Ratio/Motor/Length: 2.6L / 2.00 Ratio/Two Stroke/20"/RH Rotation
Subtotal: $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 image 0

New Yamaha 150–200HP 2/4-Stroke (1984–2024) Replacement Lower Unit | Aftermarket | Standard Rotation | Fits 20″ & 25″ Shafts | 3-Year Warranty

$1,330.89 $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 image 0
New Yamaha 150–200HP 2/4-Stroke (1984–2024) Replacement Lower Unit | Aftermarket | Standard Rotation | Fits 20″ & 25″ Shafts | 3-Year Warranty image 1
New Yamaha 150–200HP 2/4-Stroke (1984–2024) Replacement Lower Unit | Aftermarket | Standard Rotation | Fits 20″ & 25″ Shafts | 3-Year Warranty image 2
New Yamaha 150–200HP 2/4-Stroke (1984–2024) Replacement Lower Unit | Aftermarket | Standard Rotation | Fits 20″ & 25″ Shafts | 3-Year Warranty image 3

New Yamaha 150–200HP 2/4-Stroke (1984–2024) Replacement Lower Unit | Aftermarket | Standard Rotation | Fits 20″ & 25″ Shafts | 3-Year Warranty

$1,330.89 $1,199.00
Ratio/Motor/Length: 2.6L / 2.00 Ratio/Two Stroke/20"/RH Rotation
Description
Description
x

Upgrade your Yamaha 150–200HP outboard with the reliable SEI 90-416 aftermarket lower unit.
Built to match OEM performance, this unit fits both 2-stroke and 4-stroke engines from 1984–2024.
It’s a fully assembled, direct-fit replacement with a 3-year warranty—ready to install with no modifications needed.

Key Features

  • Designed for Yamaha 150–200HP outboards (1984–2024)

  • Compatible with 2-stroke and 4-stroke models (90° V6 & Inline 4)

  • Standard rotation lower unit for right-hand propellers

  • Fits 20″ and 25″ shaft lengths

  • Available with 1.86:1 or 2.00:1 gear ratios depending on engine type

  • Direct bolt-on fit — no adapter kits or changes required

  • Painted black, can be refinished to match OEM color

  • Saltwater and freshwater compatible

  • Backed by a 3-year manufacturer warranty

Specifications

Feature Details
Product Name Yamaha 150–200HP Lower Unit (SEI 90-416)
Compatible HP Range 150HP – 200HP
Years Supported 1984 – 2024
Stroke Type 2-Stroke & 4-Stroke
Compatible Models Yamaha 90° V6 & Inline 4-Cylinder
Shaft Lengths 20″ & 25″
Gear Ratios 1.86:1 or 2.00:1 (varies by model)
Rotation Standard (Right Hand)
Paint Color Black – Repaintable
Condition New – Aftermarket
Installation Direct Fit – No Modifications Required
Warranty 3-Year
Included Items Fully Assembled Lower Unit
Usage Freshwater & Saltwater Compatible
Part Codes / SKU 90-416-A20 / A25 / B20 / B20F / B25F / A20F / A25F

Why Choose the Yamaha 150–200HP Aftermarket Lower Unit?

When your Yamaha outboard’s lower unit fails, choosing the right replacement is critical.
The SEI 90-416 offers the perfect balance between cost, durability, and OEM-level performance — designed for long-term reliability and smooth operation.

  • OEM Fitment: Built to replace Yamaha factory units with no setup changes.

  • Precision Engineering: Matches factory gear ratios for ideal torque and thrust.

  • Corrosion-Resistant Build: Suitable for both saltwater and freshwater use.

  • Cost-Effective Solution: Same performance as OEM at a fraction of the price.

  • Peace of Mind: Backed by SEI’s industry-leading 3-year fault-free warranty.

 

Frequently Asked Questions – Yamaha 150–200HP Replacement Lower Unit

1. Which Yamaha outboards are compatible with this SEI 90-416 150–200HP lower unit?

The SEI 90-416 lower unit fits Yamaha 150HP to 200HP outboards manufactured from 1984 through 2024. It is designed for both 2-stroke and 4-stroke engines, including 90° V6 and Inline 4-cylinder models. The unit fits standard rotation (right-hand) applications and is suitable for both 20″ and 25″ shaft length configurations. This direct bolt-on assembly requires no adapters or modifications for fitment.

2. What gear ratios are available, and how do I select the proper ratio for my Yamaha outboard?

The SEI 90-416 offers both 1.86:1 and 2.00:1 gear ratios, depending on your engine’s model and production year. Most Yamaha 150–200HP outboards will specify the required gear ratio in the owner’s manual or on the model/serial number plate. Always match the gear ratio to your current or original lower unit for maximum performance and to prevent engine or propeller issues.

3. Is this lower unit new, rebuilt, or remanufactured?

The SEI 90-416 is a 100% brand-new aftermarket lower unit built to OEM-equivalent specifications, not remanufactured or rebuilt. It arrives fully assembled with all brand-new internal components, gears, and a pre-installed water pump for easy installation. No core exchange or deposit is required with this purchase.

4. What warranty coverage is provided, and what does it include?

Every SEI 90-416 Yamaha 150–200HP aftermarket lower unit is backed by an industry-leading 3-year fault-free warranty. The warranty covers defects in manufacturing and materials, as well as mechanical failures that occur under normal recreational operation. This coverage ensures dependable performance and peace of mind for Yamaha owners.

5. What preparation or setup is required before installation?

The unit ships painted black for corrosion protection and may be refinished to match Yamaha OEM color. It is shipped dry and must be filled with the correct marine gear oil before running. Confirm that you have the correct shaft length and gear ratio for your application. Installation is direct bolt-on—it comes fully assembled, so no additional modifications or major setup are needed beyond standard alignment and lubrication.

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.

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