Yamaha 250HP 4-Stroke (2005–2018) Replacement Lower Unit – Counter Rotation – Fits 25″ & 30″ Shafts – 2.00 Gear Ratio

Original price was: $1,921.90.Current price is: $1,699.00.

(18 customer reviews)
SKU: ST-90-429

Yamaha 250 HP 4 Stroke Counter Rotation Outboard Lower Unit – 90-429. This high-performance outboard lower unit features a water-cooled bearing carrier, side and double water intakes, and is designed for extreme performance.

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Manufacturer Warranty: 3-Year

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Return Policy: 60-day, hassle-free returns

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Trusted by 6,000+ boaters across the USA

Description
Get reliable counter-rotation performance with this SEI 90-429 aftermarket lower unit, designed to replace Yamaha LF250 4-stroke outboards (2005–2018) with 25″ or 30″ driveshafts. This replacement unit supports both early and later models with dual or side water intakes and includes a water-cooled bearing carrier for added durability.
✅ For Counter Rotation Applications Only
✅ Replaces OEM LF250 lower units with 25″ or 30″ shafts
✅ Compatible with side and dual water intake models
✅ Painted black—can be color-matched to your engine
✅ Backed by a 1-Year Limited Warranty
Specification Details
Product Name Yamaha 250HP 4-Stroke Counter Rotation Lower Unit
Compatible Models LF250 Series
Horsepower 250HP
Years Supported 2005 – 2018
Gear Ratio 2.00:1
Rotation Counter Rotation Only
Shaft Lengths 25″ & 30″
Water Intakes Dual & Side
Driveshaft Type One-piece
Color Black (Paintable)
Warranty 1 Year Limited
OEM Replaces LF250XA, LF250TXR, LF250BTXR, LF250UA, LF250TUR, LF250BTUR, LF250TURD
Part Codes 90-429-B25F (25″), 90-429-B30F (30″)
Installation Direct Fit – No Modifications Required
Condition Brand New – Aftermarket
Additional information
Weight 65 lbs
Dimensions 65 × 37 × 10 in
Ratio/Shaft

F250/ 25" Shaft/ 2.00/4 Stroke

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F250/ 30" Shaft/ 2.00/4 Stroke

Brand

Brand

SEI

Reviews (18)
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18 reviews for Yamaha 250HP 4-Stroke (2005–2018) Replacement Lower Unit – Counter Rotation – Fits 25″ & 30″ Shafts – 2.00 Gear Ratio

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  1. David Flores

    The included gasket sealed perfectly—no leaks post-install. The unit shifts seamlessly and runs cooler than my old part. A hassle-free upgrade!

  2. Cody Cannon

    Installed this on a 2005 motor—fit like a glove. Smooth engagement, no vibrations, and saved $700. Vintage boaters, this is your fix!

  3. Alexander Mcfarland

    The customer team helped me troubleshoot a minor alignment issue over the phone. The unit itself is whisper-quiet, leak-free, and handles sudden throttle changes effortlessly. OEM quality without the insane markup!

  4. Kelly Mendoza

    Thick housing—tough love!

  5. Catherine Romero

    Installed this during a family fishing trip. Took 40 minutes, and it handled rough wakes without complaint. The kids noticed the quieter engine—thanks to this unit!

  6. Phyllis Robertson

    After a $1,200 dealer quote, I gambled on this. Installed it myself in 45 minutes, saved $800, and gained smoother performance. Silent operation—why pay OEM prices?

  7. Charles Brooks

    After a decade of OEM parts, I tried this. The stainless steel components are thicker, the shifts are faster, and the price is unbeatable. Why didn’t I switch sooner?

  8. David Kline

    Pre-greased fittings saved me 30 minutes of messy work. Installed solo, and it’s been flawless through 50 hours of runtime. DIYers, this is your holy grail!

  9. Charles Lane

    The delivery was so fast I thought it was a mistake. Installed the unit in 40 minutes, and it’s handled everything from idling to WOT without issue. Zero complaints!

  10. Matthew Bailey

    The splines aligned perfectly on the first try. After eight weeks, the oil is still clear, and the unit runs silently. A flawless replacement!

  11. Kelly Martin

    Vibration-free—smooth rides!

  12. Shane Horn

    Eco-friendly packaging impressed my green-hearted crew. The unit handles heavy loads effortlessly—no complaints after 60 days. A planet-friendly choice for eco-conscious captains!

  13. Jack Harrington

    Tested in Alaskan fjords and Caribbean reefs—no performance drop. The seals stay flexible in freezing temps, and shifts stay precise in tropical heat. A four-season workhorse!

  14. Jared Dean

    24/7 support and leak-proof design—stellar product!

  15. Kimberly Nguyen

    Quick email support resolved my query. Product is stellar!

  16. Kayla Peterson

    I’ve put 20 hours on this unit since installation. The oil stays clean, the temperature stays steady, and there’s no vibration. Couldn’t ask for a better aftermarket solution!

  17. Jacqueline Bullock

    This unit arrived with pre-filled gear lube and labeled hardware. Installed it during a rainstorm—still took under an hour. Shifts are seamless, and the anti-vibration design quiets the entire boat!

  18. Jennifer Serrano

    I’ve recommended this to three friends already. The unit is robust, the shifts are seamless, and the oil stays contaminant-free. OEM quality without the markup!

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