DOWNLOAD Honda 20 25 30 HP Outboard Shop Service Manual BF20A BF25A, BF25D BF30D

Download DOWNLOAD Honda 20 25 30 HP Outboard Shop Service Manual BF20A BF25A, BF25D BF30D


DOWNLOAD Honda 20 25 30 HP Outboard Shop Service Manual BF20A-BF25A, BF25D-BF30D

Service Repair Manual Application: Honda Marine Outboard BF20A-BF25A, BF25D-BF30D 20HP (20-HP), 25HP (25-HP) 30HP (30-HP) 4-Stroke Carburetor BF-20A, 25A, 25D, 30D, Original Honda factory service manual. This manual covers the construction, function and servicing procedures of the Honda BFZOAIBF25A outboard motors. Illustrations in this manual are based primarily on the BF25A LRS. Publication date 1994.

This service manual describes the 20 HP, 25 hp, 30hp service procedures for the complete Honda Outboard motor. Follow the Maintenance Schedule recommendations to ensure that the engine is in peak operating condition. Performing the scheduled maintenance is very important. It compensates for the initial wear that occurs during the life of the engine.

All chapters in the service manuals apply to the whole Honda outboard engine and illustrates procedures for removal & installation of components that are in detailed step-by-step fashion.

All service manual chapters start with an assembly or system illustration, diagrams, exploded parts view, service information and troubleshooting for the section. The subsequent pages give detailed procedures. If you dont know the source of the trouble, go to the troubleshooting page located at the end of the manual for a list of causes and effects to determine the problem.

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Typical chapters in a Honda Outboard Service Manual (chapters may differ depending on year/model):

This manual covers all repair topics such as:

General Information
Periodic Maintenance
Fuel System
Tech Features
Rigging info
Power Unit
Lower Unit
Bracket Unit
Electrical System
Detailed Diagrams, illustrations, photos, exploded views and step-by-step Instructions
Diagnostics and similar topics.

Manual Language: ENGLISH
Pages: 434
File Format: PDF
File Delivered In: PDF Format
Bookmarked for easy navigation: NO (You can run word or key phrase search)
Zoom in/out: YES
Works on all computers!



Cylinder compression :

Standard : 1300 1700 kPa (13 17 kg/cm2, 185 242 psi.)

Max. difference between any other cylinders : 100kPa (1.0 kg/cm2, 14 psi.)

NOTE: Figures shown are guidelines only, not absolute service limits. Low compression pressure can indicate one or more of following
Excessively worn cylinder wall
Worn piston or piston rings
Stuck piston rings
Poor seating of valves
Ruptured or otherwise damaged cylinder head gasket


1. Start engine and allow to warm up, then shut engine off.
2. Remove STBD / PORT side covers.
3. Remove all spark plugs.
4. Install compression gauge hose attachment into plug hole, then connect compression gauge hose to gauge hose attachment and compression gauge.

Compression gauge
Compression gauge hose
Compression gauge hose attachment

5. Disconnect safety lanyard (switch plate) from emergency stop switch. Disconnect the safety lanyard from the emergency stop switch prior to cranking the engine. This will prevent any residual fuel discharged from the cylinders being ignited by a spark discharge from the spark plug caps.
6. Disconnect remote control throttle cable from throttle lever.
7. Move and hold throttle lever in full-open position.
8. While cranking engine with starter motor, note maximum compression pressure reading on gauge for each cylinder.
9. Reinstall parts removed earlier. (spark plugs, side covers, etc.)


Excessive exhaust noise
Deformed exhaust system
Exhaust gas leaks
Poor performance

Clogged muffler
Broken exhaust system
Exhaust gas leaks

Oil level too low – high oil consumption

Oil consumption
External oil leak
Worn piston rings or incorrect piston ring installation
Worn cylinder
Worn valve guide or stem seals
Oil pump worn or damaged
Oil contamination

Oil or filter not changed often enough
Worn piston rings or incorrect piston ring installation
Worn valve guide or stem seals

Engine cranks but wont start

No fuel in tank
No fuel to carburetor
Clogged fuel strainer
Clogged fuel line
Clogged fuel tank breather tube
Misadjusted fuel level
Too much fuel getting to the engine
Clogged air cleaner
Flooded carburetor
Intake air leak
Contaminated/deteriorated fuel
Clogged jets
Clogged starting enrichment valve circuit
Improper starting enrichment valve operation
Improper throttle operation
No spark at plug (faulty ignition system)
Lean mixture

Clogged fuel jets
Faulty float valve
Float level too low
Restricted fuel line
Clogged carburetor air vent tube
Restricted fuel tank breather tube
Intake air leak
Faulty vacuum piston
Faulty throttle valve
Rich mixture

Starting enrichment valve open (ON)
Clogged air jets
Faulty float valve
Float level too high
Dirty air cleaner
Worn jet needle or needle jet
Faulty vacuum piston
Engine stalls, hard to start, rough idling

Restricted fuel line
Fuel mixture too lean/rich
Contaminated/deteriorated fuel
Clogged jets
Intake air leak
Mis-adjusted idle speed
Misadjusted pilot screw
Misadjusted float level
Restricted fuel tank breather tube
Clogged air cleaner
Clogged slow circuit
Clogged starting enrichment valve circuit
Faulty ignition system
Backfiring or misfiring during acceleration

Lean mixture
Faulty ignition system
Poor performance and poor fuel economy

Clogged fuel system
Faulty ignition system

Engine top-end problems usually affect engine performance. These can be diagnosed by a compression test, or by tracing top-end noise with a sounding rod or stethoscope. If the performance is poor at low speeds, check for a white smoke in the crankcase breather tube. If the tube is smoky, check for seized piston ring

Compression too low, hard starting or poor performance at low speed


Incorrect valve adjustment
Burned or bent valves
Incorrect valve timing
Broken valve spring
Uneven valve seating
Valve stuck open

Cylinder head

Leaking or damaged cylinder head gasket
Warped or cracked cylinder head
Loose spark plug

Compression too high

Excessive carbon build-up on piston head or
combustion chamber
Worn or damaged decompressor system

Excessive smoke

Worn valve stem or valve guide
Damaged stem seal
Cylinder/piston problem

Excessive noise

Incorrect valve clearance
Sticking valve or broken valve spring
Excessive worn valve seat
Worn or damaged camshaft
Worn rocker arm and/or shaft
Worn rocker arm follower or valve stem end
Worn or damaged push rod and/or cam follower
Worn cam chain
Worn or damaged cam chain tension er
Worn cam sprocket teeth
Cylinder/piston problem

Rough idle

Low cylinder compression


Compression too low, hard starting or poor performance at low speed

Leaking cylinder head gasket
Worn, stuck or broken piston ring
Worn or damaged cylinder and piston
Bent connecting rod
Compression too high, overheating or knocking

Excessive carbon built-up on piston head or combustion chamber
Excessive smoke

Worn cylinder, piston or piston rings
Improper installation of piston rings
Scored or scratched piston or cylinder wall
Abnormal noise

Worn piston pin or piston pin hole
Worn connecting rod small end
Worn cylinder, piston or piston rings

Starter motor turns, but engine does not turn

Faulty starter clutch
Damaged starter reduction gear

Excessive engine noise

Worn, seized or chipped transmission gears
Worn transmission bearings
Worn or damaged connecting rod bearing
Worn crankshaft main journal bearing
Worn connecting rod small end
Worn balancer bearing
Improper balancer installation
Consistent noise during cruising

Oil level too low
Foreign matter contaminating gear oil
Worn or damaged bearing
Worn or damaged ring gear and pinion gear
Deformed ring gear or differential case
Improper tooth contact between ring gear and pinion gear
Abnormal noises at start or during acceleration

Excessive backlash between ring gear and pinion gear
Worn differential splines
Loose fasteners
Worn cone spring or shim
Oil leak

Oil level too high
Clogged breather
Damaged seals
Loose case cover bolt
Over heating – Overheating

Oil level too low
Insufficient backlash between ring gear and pinion gear
Oil leak

Oil level too high
Clogged breather
Damaged seals
Loose case cover bolt

Honda Outboard Service Manual, Repair Manual, Shop Manual, Owner’s Workshop Manual, Engine Repair Guide, Handbook, Book, Learning Guide, Study Guide, Factory Engine Rebuild Manual. Honda Marine Outboard Model name.

Propeller Information Charts, Propeller Selection, Propeller Removal & Installation, aluminum prop, steel prop, 4 blades, 3 blade, Torque Specifications, Inspection And Maintenance Schedule, Spark Plug Inspection, Fuse Replacement, Electric Start Models, Start in Gear Protection, Transom Bracket, Checking Power Trim Fluid, Power Trim System, Fuel System, Electric Fuel Pump, Recommended Battery, Battery Inspection, Battery Cable Connections .

Powerhead Views, Installation Drawing, Trim Tab Adjustment, Trim-In Stop Adjustment, Painting Procedures, Decals, Decal Application, Steering Cable, Steering Link Rod, Hoses, and Control Cables, Flywheel Assembly, Flywheel, Ignition Components, Coils, Ignition Test Procedures, Ignition Component Description, Starting and Idling, Starter Relay, Starter Solenoid Test, Starter Motor, Alternator System Test, 25 Ampere Stator, Stator Removal and Installation, Stator Coil, Stator Coil Peak Voltage, Electronic Control Module (ECM), Air Temperature Sensor, Throttle Position Sensor (TPS), Engine Water Temperature Sensor, Crank Position Sensors (CPS), Idle Air Control (IAC).

Water Pump, Water Pump Reassembly and Installation, Oil Pump, Oil Pressure Switch, Timing Belt Removal and Installation, Rectifier, Throttle Shutter Synchronization, Throttle Cam Adjustment, Throttle Shaft Adjustment, Pressure Regulator, Fuel Hoses, 10 ethanol in gasoline, 10 ethanol gas problems, Gas, 91, Octane, 89 Petrol, 93 Octane, Fuel Additive, Fuel Inj system, Injectors, Adjusting, Carb, Carburetor, Rebuild Carburetor Warming Up, Cold Start, Fuel Pump, Fuel Filter, Water In Fuel Filter, 25 motor, Honda outboard 25hp outbord engine.

Rebuilt cyliner Block, Cylinder Block And Crankcase, Cylinder Head Removal, Cylinder Head Disassembly, Camshaft, Thermostat, Valves, Valve Springs, Cylinder Head, Valve Guides, Valve Seats, Cylinder Head Installation, Following Cylinder Head Installation, Shift Shaft, Upper Drive Shaft Bearing, Wiring Diagram, Fuel Flow Diagram, Oil Flow Diagram, Water Flow Diagram, Throttle Shift Linkage, Tiller Handle, Manual Starter.

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