Yamaha LF115XB2 115HP 25″ Counter-Rotation Outboard

The Yamaha LF115XB2 is a 115hp counter rotation outboard designed with a 25-inch shaft for multi-engine offshore boats. This 1.8-liter inline-4 platform produces immense structural density through its 1832 cc displacement while maintaining an optimized dry weight of 386 lbs to maximize pure marine performance. Engineered explicitly for mid-transom configurations, the 25-inch shaft length helps support ideal propeller depth and balanced tracking across heavy-duty fiberglass hulls navigating rough open ocean waters.

The 5300 to 6300 RPM operating range should be matched to the boat, load, propeller, and intended use. The 2.15:1 gear ratio should be matched with an appropriate propeller and boat setup. under heavy loads. This Japanese-built outboard leverages advanced block harmonics to eliminate low-frequency hull vibrations during severe long-range deep-sea operations.

Technical Specifications of Yamaha LF115XB2

- Electronic fuel injection utilizes a multi-point sequential track to maximize total thermal efficiency across all cylinders.
- A heavy-duty 35 gross amp alternator generates power to keep house battery banks charged.
- The remote mechanical control system replaces old setups with responsive vessel tracking adjustments.
- The advanced power trim and tilt mechanism simplifies trailing and shallow-water operation by moving the lower unit out of harm.
- An extensive 3.2-liter oil sump helps support optimal thermal dissipation and continuous lubrication during hard wide-open throttle runs.
- The specialized counter-rotation gearcase balances out propeller torque to maintain tracking on multi-engine express cruisers.

DOHC In-Line Four Architecture

A 16-valve double overhead camshaft design treats the cylinder layout of this inline-4 block to optimize total thermal efficiency. This engineering process shaves critical response lag off the powerhead while drastically improving volumetric efficiency under severe load environments.

Sequential Track Fuel Induction

Electronic fuel injection sprays gasoline straight into the intake tracks for clean combustion cycles on 87 octane fuel. This delivery system is designed to support immediate throttle response and flawless cold starts during changing early morning coastal marine conditions.

Hydrodynamic Gear Housing Profile

Oversized internal gears and a 2.15:1 gear ratio profile minimize underwater drag at high cruising speeds. This structural configuration mitigates lower-unit gear chatter and helps support smooth power transmission to the hub.

Mechanical Remote Helm Layout

Digital electronic control systems integrate directly with the steering setup to automate multi-engine tracking and trim adjustments. This network allows captains to execute precise docking maneuvers with a single intuitive control layout.

Opposing Twin Engine Configuration

Twin-engine configurations for mid-size offshore hulls, multi-engine coastal center consoles, walkarounds, and deep-V bay boats from 20 to 28 feet are targeted. The mid-length shaft delivers leverage and structural vibration dampening when driving through steep waves.

Cowling Access And Lubrication

Fast access to critical checking points is provided by a multi-piece outer cowling structure that cuts service times down significantly. Changing the internal fluid volume remains completely clean thanks to an engineered drain plug location that prevents spoiling oil.Maintenance note: Follow the manufacturer’s service procedures and lubrication specifications for the engine and gearcase.