FourStroke 2.5 HP


Go anywhere with portable power.
Taking the fun with you is one of the great advantages of owning an inflatable boat or small fishing boat. Mercury offers a complete line of extremely light portable FourStroke outboards, with the widest range of models to choose from. So wherever you and your boat go, your Mercury portable FourStroke can also go. The entire line makes operation and portability easy with smart, simple features. Plus, clean, quiet, fuel-efficient FourStroke performance makes them the obvious power of choice.


Engine Specs

  • Displacement (CID/CC) : 5.2 / 85
  • Engine type : 1 cylinder
  • Bore & Stroke (in/mm) : 2.16 x 1.42in / 55 x 36mm
  • Fuel System : Carbureted
  • Fuel Induction System : 2-valve pushrod (overhead valve)
  • Cooling System : Water-cooled with thermostat
  • Full Throttle RPM Range : 4500-5500
  • Ignition : CDI w/electronic spark advance
  • Starting : Manual
  • Gear Shift : F-N
  • Steering : Tiller with 360° turning
  • Trim Positions : 4
  • Trim System : 4 position
  • Recommended Oil : Mercury FourStroke Oil 10W-30
  • CARB Star Rating : 3
  • Exhaust System : Above prop
  • Dry Weight * Lightest model available : 38 lbs / 17 kg
  • Engine Protection Operator Warning System : Over-rev
  • Gearcase Ratio : 2.15:1
  • Gearcase options: Standard
  • Recommended Fuel : 87 octane/up to 10% ethanol


  • HP/Kw @ Prop : 2.5 / 1.9
  • Shaft Length : 15 in (381mm)
  • Shallow Water Trim Range : 16 degrees


Standard Features

Specifications are subject to change without notice



Weighing just 38 and 57 pounds, respectively, our 2.5 – 3.5hp and 4 – 6hp FourStroke outboards are easy to lift and carry.

Shallow Water.

Multiple trim positions enhance performance and enable shallow-water operation.

Precise Control.

Mercury 2.5 and 3.5hp FourStroke engines feature neutral-forward shifting with 360-degree steering for full thrust in all directions.

Easy to Start.

Automatic decompression bleeds off cylinder pressure to reduce the pulling force required to start the engine.

  • A Better Grip: Mercury’s twist-throttle tiller handle is longer for better control – plus it folds for easy, compact storage.
  • No Vibration is Good Vibration: Your steering hand will thank you. On average, Mercury’s 3.5hp fourstroke has 32% less tiller handle vibration than competitive outboards.
  • They’ll Never Hold You Back: Mercury’s 2.5 – 3.5hp portable outboards are designed from the start to be compact, lightweight and easier to carry. By utilizing Mercury’s patented one-piece integrated cylinderblock design, we’ve eliminated gaskets and fasteners and made the powerhead much more compact and lightweight.
  • Twist and Shout: Spinning in circles to turn around can make anyone dizzy. That’s why Mercury’s 2.5 and 3.5 hp FourStrokes offer 360° steering and a twist grip throttle. The tiller handle can be turned over and the engine rotated to reverse the thrust.