Our 139-cc 4-hp portable outboard mirrors our OHV F6, with a couple less horses. It features the same ergonomic, easy-grip starter handle with a built-in decompression device for effortless starts. The F4 also features a built-in fuel tank with the option of switchable access to an additional external tank for amazing extended range. There’s no stopping this little brute.
Power & Performance
- Lightweight, Portable Power: They may weigh as little as 37 pounds, but these Overhead-Valve portable outboards are packed with features that create smooth, quiet power. This includes a CDI or TCI ignition system, an optimally balanced crankshaft, a long span mounting system and a labyrinth exhaust.
- Ultra-Low Emissions: The Portable F6, F4 and F2.5 are California Air Resources Board (C.A.R.B.) Three-Star Rated for Ultra-Low Emissions and meet federal EPA requirements.
- Record Setting Fuel Efficiency: Small motors use less fuel, but according to the Guinness Book of World Records, the Yamaha F4 actually set a world record for fuel efficiency, traveling 67.27 continuous statute miles on one gallon of gas.
Reliability & Durability
- Easy Operation: The F6, F4 and F2.5 feature built-in, see through fuel tanks. The F6 and F4 also feature switchable access to an optional, 3.1-gallon external fuel tank for extended range.
- Wet Sump: A pressurized oil delivery system that incorporates a compact and durable oil pump to keep all of the moving parts of their Overhead Valve systems lubricated and running smoothly for maximum reliability.
- Corrosion Protection: Combined with our proprietary alloy (YDC-30), our exclusive Phaze Five™ electro-deposited, anti-corrosive paint system provides a tough, five-layer barrier against corrosion. This protection is standard on all Yamaha Portable outboards.
- Maximum Efficiency: The F6, F4 and F2.5 have a carburetor with a factory-selected setting for maximum efficiency, which helps them achieve a C.A.R.B. Three-Star Rating for Ultra-Low Emissions. Additionally, automatic decompression, built-in auxiliary priming and start-in-gear prevention help make for easier starts.
Convenience & Control
- Easy Storage: Yamaha’s F2.5, F4, and F6 feature our Easy Storage Oil Retention System. This pressurized oiling system prevents leaks, enabling on-side storage.
- Comfortable Control: Incredibly nimble, the F6 and F4 feature 180-degree steering and the F2.5 features 360-degree steering with a dynamically balanced and dampened twist-grip throttle for comfort and convenient maneuverabilty.
- Portability and Storage: Built-in front and rear handles make these lightweights easy to carry. Resting pads and an easy oil retention system allow for convenient on-side storage without cowling scuffs or oil leakage.
Model Specific Features
- Tiller-handle control with forward-neutral-reverse shifting and an ergonomic twist-grip throttle
- Only 59 pounds (15” shaft model)
- Available in 15” and 20” shaft lengths
- Solid 6-amp alternator
- Engine Type: 1 cyl
- Displacement: 139cc
- Bore x Stroke: 62 x 46mm (2.44 x 1.81in)
- Prop Shaft Horsepower: 4hp at 4500 rpm
- Full Throttle RPM Range: 4000 ~ 5000
- Alternator Output at W.O.T.: 6 Amp
- Compression Ratio: 8.9:1
- Fuel Induction System: Carb
- Weight*: 27 kg (59 lbs)
- Recommended Fuel: Octane 87
- Recommended Engine Oil: Yamalube® 4M (See owner's manual)
- Recommended Fuel Filtration: N/A
- C.A.R.B. Rating: 3-Star
- Exhaust: Above Propeller
- Intake: 2
- Ignition: CDI
- Spark Plug: CR6HSB
- Alternator Output: 6 Amp
- Starting System: Manual
- Lubrication: Wet Sump
- Engine Oil Capacity: 0.6L
- Recommended Cooling: Thermostatic Control
- Ethanol Blend Limit: 10% Maximum
- Gear Ratio: 2.08:1
- Gear Shift: Forward, Neutral, Reverse
- Shaft Length: 15"
- Degree of Tilt: 69°
- Degree of Trim: -4° through +16°
- Dry Weight: 27 kg (59 lbs)
- Mounting Centers: N/A
- Steering Angle (maximum): 90° from center, either direction
- Warranty: Limited 3-Year Pleasure, 3-Year Government, 1-Year Commercial
Weight refers to shortest shaft length, and is measured without motor oil, gearcase oil and propeller (except models 25 hp and under, which include a standard propeller). All Jet model weights include the jet pump assembly (weight estimated).