Yamaha F115JB 115HP 20in Jet Drive FourStroke Outboard Motor

Description

Marine grade hardened aluminum alloy encases the Yamaha F115JB Outboard Motor jet drive powerhead. This 1.8-liter inline four-cylinder four-stroke engine produces 80 jet pump horsepower from a 115-horsepower crankshaft rating at 5,500 RPM. Designed with an axial-flow jet pump, it navigates shallow rock-strewn rivers and shallow tidal flats where traditional propeller lower units risk severe impact damage.

High-tensile aluminum alloy castings form the engine block and intake jet casing to resist abrasive silt erosion. Cast iron cylinder liners preserve bore roundness under continuous commercial load. A stainless steel jet pump impeller draws raw river water to cool internal engine passages. The unit weighs 378 lbs dry, holds 3.4 quarts of engine oil, and mounts to 20-inch boat transoms.

Key Features of Yamaha F115JB

River navigation pilots buy Yamaha F115JB inboard engine packages to operate shallow-water freight skiffs. The jet drive design eliminates lower gearcase snags when navigating gravel bars and rapid river chutes.

• 1,832 cc four-cylinder four-stroke engine delivers dependable high-rpm jet pumping power.
• Axial-flow jet pump draws intake water flush with the vessel hull bottom.
• Multi-point electronic fuel injection meters fuel with precision for maximum operating range.
• Stainless steel jet impeller resists wear from abrasive river sand and gravel debris.
• Electric power trim and tilt adjusts jet nozzle running angle from console controls.
• 35-amp high-output alternator powers commercial navigation sounders and deck floodlights.
• Yamaha F115JB jet pump architecture protects propulsion components in shallow river rapids.
• Freshwater flush connector allows fast engine cooling system flushing at dockside.

Dynamic Combustion Hydraulic Thrust

Electronic injectors pulse fuel at 3.0 bar pressure to maintain cooling water temperatures between 140°F and 160°F. The 16-valve dual overhead camshaft powerhead generates 105 lb-ft torque at 4,000 RPM to feed the jet nozzle. Specific fuel consumption rates hold at 5.2 GPH during commercial river cruise settings. Internal seawater jackets absorb combustion heat to prevent block distortion under prolonged heavy-load river ascents.

Transom Integration Jet Tunnel Envelope

Heavy-duty transom mounting brackets bolt to 20-inch reinforced transoms using standard BIA bolt patterns. The jet intake shoe mounts flush with the bottom boat plating to intake clean water without turbulence. Exhaust vents through internal relief passages above the waterline at idle to adhere to ABYC noise standards. The mechanical steering cable attaches to the jet nozzle tiller arm with 30 degrees of lateral deflection.

River Duty Operating Guidelines

Console-mounted throttles provide immediate waterjet nozzle response across forward and reverse bucket positions. This engine is not engineered for deep weed-choked swamps, dry land operation, or aerated offshore surface piercing racing hulls. Following rigorous preventative maintenance intervals protects the jet pump and engine block from premature sediment wear.

• Examine the jet intake grate for stone blockages and verify oil level each shift.
• Change engine crankcase oil and replace lube filters every 100 hours.
• Inspect jet impeller clearance and replace internal sacrificial anodes every 12 months.

Factory Warranty Manifest Manifest

Commercial users receive a 3-Year limited factory warranty against manufacturing flaws. Shipped in a reinforced wooden export crate, the package includes the 115HP jet drive motor, jet pump unit, steering cable hardware, external fuel-water separator, and factory service documentation.