1978–2001 Honda BF2/BF5/BF8/BF15/ BF25/BF35/BF40/ BF50/BF75/BF115/BF130 Outboard Engine Shop Manual (P/N 18-01200)

This shop manual covers 1978–2001 Honda four-stroke outboards, including carbureted engines, BF115A/BF130A PGM-FI models, conventional lower units and the specified jet-drive applications.

PDF Reading, Wiring Detail and Page Count

Search, bookmarks and wiring detail: PDF text search is not available. Three file-part bookmarks provide limited navigation; the first has no usable destination. Small labels in the wiring diagrams require page rotation and zooming.

One printable, English-language, 369-page PDF, including two contents pages, a four-page glossary and a five-page master index.

Powerhead, Fuel-System and Drive Service

• Powerhead repair: Step-by-step procedures for cylinder-head service, camshaft removal, timing-belt replacement and adjustment, internal inspection, and engine reconditioning.

• Fuel-system service: Carburetor disassembly, float inspection, multi-carburetor synchronization, fuel-pump testing, and PGM-FI component diagnosis and replacement.

• Ignition and electrical diagnosis: Breaker-point, transistorized and CDI system tests, charging-circuit checks, starter-motor service, component-location views, and model-specific wiring diagrams.

• Lubrication and cooling: Oil-pressure diagnosis, oil-pump inspection, water-pump overhaul, thermostat testing, and oil-pressure and overheat warning-system checks.

• Lower-unit and jet-drive repair: Gearcase disassembly, bearing and seal replacement, gear-shim selection, backlash adjustment, jet-impeller shimming, and reverse-gate adjustment.

• Trim, tilt and controls: Manual and gas-assisted tilt service, power trim-and-tilt motor and hydraulic-unit repair, system bleeding, remote-control box service, and tiller-handle adjustments.

• Hand rewind starters: Model-specific removal, disassembly, spring and rope inspection, reassembly, and neutral-starting cable adjustment where fitted.

Written for owners maintaining their own outboards, the manual also explains when a repair calls for tools, experience or professional help beyond a home workshop.

Engine Reconditioning and Routine Maintenance

The powerhead chapter goes beyond external component replacement to cover cylinder-head disassembly, valve and guide inspection, cylinder-bore measurement, piston and connecting-rod checks, and crankshaft-bearing inspection. Model-specific rebuilding tables distinguish standard dimensions from service limits.

Camshaft timing-mark views accompany the belt and valve-service procedures. Compression and oil-pressure tests help assess engine condition before deciding whether a tune-up or internal repair is appropriate.

Engine-oil and lower-unit capacity tables support routine servicing, alongside maintenance intervals, winter-storage and spring-commissioning checklists. The tools section explains vacuum gauges, micrometers and bore-measuring tools, with fastener torque tables organized by grade and pitch and separate conversion charts.

Carburetors and PGM-FI Diagnosis

Carburetor coverage distinguishes adjustable floats from nonadjustable assemblies and includes vacuum-gauge synchronization. Pump service separates rebuildable diaphragm pumps from mechanical plunger pumps that are replaced as complete units.

For the injected engines, the manual explains MIL blink-code reading and clearing, sensor checks, fuel-pressure testing, and vapor-separator service. The vapor separator tank schematic and model-specific hose-routing illustrations show how the supply and return circuits connect.

Always ensure your work area is well-ventilated and strictly adhere to standard marine safety protocols when handling these fuel system components.

Electrical Fault Tracing

The electrical chapter combines circuit-testing explanations with ignition-coil, pulser-coil, CDI, regulator/rectifier and starter-solenoid checks. Its test charts and component-location views help match the test procedure to the installed ignition system before replacing parts.

Wiring coverage includes the BF115/130 Engine Control Unit Schematic and separate starting, fuel-pump, trim-angle sensor and tilt-control circuits. Earlier engines have their own schematics and serial-specific ignition references.

Gearcases and Jet Drives

The lower-unit chapter distinguishes forward-only units from reversing gearcases and standard-rotation units from counterrotating assemblies. The legacy BF20 and BF50 designations refer to the small 2 hp and 5 hp engines, respectively; they should not be confused with later model naming.

A BF35A gearcase cutaway, exploded assembly views and shim-selection tables support bearing, gear and clutch-shifter work. Jet-drive coverage includes an exploded lower-unit view, impeller clearance adjustment and reverse-gate service. The jet-drive chapter recommends dealer service for dismantling the driveshaft bearing assembly.

The cooling-system notes warn that running a water-cooled engine without water can damage the pump impeller. The lower-unit inspection section explains how fishing line can damage propeller-shaft seals and allow water into the gearcase.

Trim Hydraulics and Operating Controls

Power trim-and-tilt coverage includes motor inspection, hydraulic-unit disassembly, rod-compression testing and bleeding procedures. Remote-control and tiller sections cover switch testing, throttle-cable adjustment and linkage checks; recoil-starter procedures are grouped by engine family.

A Preview of Valve and Carburetor Settings

For BF115A/BF130A engines, the cold valve-clearance procedures specify 0.24–0.28 mm at the intake valves and 0.28–0.32 mm at the exhaust valves.

The carburetor tables list adjustable float heights of 14 mm for the BF25A and 13 mm for the BF30A, measured with the carburetor body upright. These are separate model-specific settings, rather than a shared adjustment for both engines.