This Bay Manufacturing 611A Outboard Extension Kit provides a professional-grade solution for converting Mercury 135–250 HP 2-stroke V-6 outboards from a 25-inch shaft to a 30-inch shaft. Designed for long-lasting performance, each kit includes stainless steel shafts and hardware, while the spacer housing is cast from the same high-quality alloy used in OEM production.
Ideal for applications requiring a longer shaft length—such as deeper transoms, improved propeller efficiency, or reduced cavitation—this kit delivers precision fit, durability, and optimal engine performance. A 1-year Bay Manufacturing warranty is included.
Product Features
- Adds 5 inches of shaft length (25" → 30" conversion)
- Heavy-duty stainless steel shafts and hardware
- Spacer housing cast using OEM-grade alloy
- Compatible with a wide range of Mercury 135–250 HP V-6 engines
- Direct bolt-on installation
- Designed for high-strength, corrosion-resistant marine use
- Includes all necessary components for installation
- Backed by a 1-year manufacturer warranty
Compatibility Requirements
Your engine MUST match all specifications below for proper fit.
✔ This 611A Kit fits motors going from 25 inches to 30 inches.
Supported Horsepower & Models
135–150 HP
| HP | Stroke | Model Notes |
|---|---|---|
| 135 | 2-Stroke | – |
| 150 | 2-Stroke | Fits V-6 (NOT old inline 6) |
| 150 Pro XS | 2-Stroke | V-6 only |
175 HP (2-Stroke, V-6)
Compatible with:
| Model | Serial Numbers |
|---|---|
| 2.5 Liter, Optimax, XR4 Magnum, XR6 | 6618750 & Up, OG303046 & Up, 0T908388 & Up, B242885 & Up, C100861 & Up |
200 HP
| HP | Stroke | Model | Serial Numbers |
|---|---|---|---|
| 200 | 2-Stroke | 2.5 Liter EFI, XR1, XR6 | OG303046 & Up, 0T235136 & Up |
| 200 | 2-Stroke | V-6 | C100861 & Up, 5363918 & Up |
220–225 HP (2-Stroke, V-6)
| HP | Stroke | Serial Numbers |
|---|---|---|
| 220–225 | 2-Stroke | 5628028 & Up |
225–250 HP (2-Stroke)
| HP | Stroke | Year |
|---|---|---|
| 225, 250 | 2-Stroke, 2.5 Liter | 1994–1998 |
Compatible Serial Numbers (from Bay Manufacturing documentation)
- 6042946 & Up – 150 HP V-6
- B242885 & Up – 175 HP XR4 Magnum
- C100861 & Up – 175 & 200 HP
- 6618751 & Up – 175 HP V-6
- 5363918 & Up – 200 HP V-6
Parts Included
- (1) 5" Extension Housing
- (1) 5" Driveshaft
- (1) 5" Shift Shaft
- (1) 5" Water Tube
- (5) Studs & Nuts
- (1) Screw
- (2) Dowel Pins
Additional Information
- Converts compatible Mercury outboards from 25" to 30" shaft length
- Built using marine-grade materials with OEM-level reliability
- Some spacers arrive painted black; others ship unpainted with a sandblasted finish
- Not eligible for return except for warranty claims
Shipping Information
Additional shipping fees to Alaska, Hawaii, U.S. Territories, or international destinations will be calculated after checkout.
A PayPal request will be emailed for any additional charges.
(Some items may be excluded from international shipping.)
Customer Support
For questions or to confirm compatibility, please email customerservice@marinepartswarehouse.com .
Please include your engine model or serial number to help confirm proper fitment before ordering.
