Honda · Outboard

Honda BF40 / BF50

Honda’s 808 cm³ three-cylinder four-stroke (70 × 70 mm, belt-driven overhead camshaft, two valves per cylinder) was sold as the carburettor BF40A/BF50A until the 2008 model change (Honda’s oldest owner’s manual for it dates from 1994) and has been the fuel-injected BF40D/BF50D ever since. The BF40D and BF50D are the same engine in two power settings, with PGM-FI injection and 17 A of charging current; Honda’s catalogues split them into D, DK2 and the restyled DK4 of 2017, and most wear parts below carry the same number in all three. Impeller, oil filter, timing belt and drain plug washer also fit the A engines, but spark plugs, the thermostat of early A engines and the whole fuel system differ, so check the serial plate before ordering (BAY…/BAZ… = A, BBDJ/BBEJ = D). The older BF35A/BF45A share many of these parts; the BF60 (since 2009) and the European BF40E are 998 cm³ engines and are not covered here.

Manuals & documents
Wear parts & part numbers
Service intervals
Specifications
Good to know
Videos & how-tos
On the marketplace

Manuals & documents

The links go straight to Honda. We host no manuals or drawings — the manufacturer’s copy is the current one.

Owner’s manual BF40D / BF50D K4 (32ZZ4647, 2026 edition, from serials BBDJ-1322063 / BBEJ-1333966) Operation manual honda.co.jp · PDF · EN · DE · FR
Owner’s manual BF40D / BF50D, first European edition (32ZZ4601, 2009) Operation manual honda.co.jp · PDF · EN · DE
Owner’s manual BF40A / BF50A (BF40A4 / BF50A4, 32ZW360701, 2003) Operation manual honda.co.jp · PDF · EN · DE · FR
Owner’s manual BF40D / BF50D, US edition 2024 (serials BBDJ / BBEJ-1100001 on) Operation manual cdn.powerequipment.honda.com · PDF · EN
Owner’s manual BF40D / BF50D, US edition 2009 (serials 1000001–1099999) Operation manual cdn.powerequipment.honda.com · PDF · EN
Owner’s manual BF40A / BF50A, US edition 2006 (serials BAYS / BAZS-3700001 on) Operation manual cdn.powerequipment.honda.com · PDF · EN
Owner’s manual BF35A / BF40A / BF50A, 1994 (serials 1000001–1999999, scanned) Operation manual cdn.powerequipment.honda.com · PDF · EN
Honda Marine (US): BF40 owner’s manuals by serial range Manual portal marine.honda.com · EN
Honda Marine (US): BF50 owner’s manuals by serial range Manual portal marine.honda.com · EN
Honda Motor Europe owner’s manual portal (choose model and edition) Manual portal honda.co.jp · EN
BF40/BF50 model page with specifications (Honda Marine US) Product page marine.honda.com · EN
BF40/BF50 specifications (Honda UK) Product page honda.co.uk · EN
Honda press release on the fuel-injected BF40/BF50 (March 2008) Press release global.honda · EN

Wear parts & part numbers

Part	OEM number	Also fits	Note
Raw water pump impeller	`19210-ZV5-003`^1,2,3,4,5	—	The same impeller in every BF40A/BF50A and BF40D/BF50D catalogue (and in the BF35A, BF45A and BF60A); Honda’s impeller pump kits below are listed alongside it.
Impeller kit (with gasket)	`06192-ZV5-023`^6,7,8,9,10replaces 06192-ZV5-003	—	One of two Honda impeller pump kits; the catalogue lists it for every A and D engine without giving the contents. A UK Honda dealer sells it, as impeller and gaskets, for the carburettor models only.
Impeller kit (with gasket)	`06193-ZV5-040`^11,7,8,9,12replaces 06193-ZV5-020replaces 06193-ZV5-010	—	The second Honda impeller pump kit in the same catalogues: -010 for the A engines, -020 for the D engines, both now supplied as -040. The UK dealer sells -020 as the impeller kit for the 2008+ fuel-injected engines.
Engine oil filter	`15400-ZZ3-003`^{13,14,15,16,17,18,19}replaces 15400-PFB-014replaces 15400-PFB-007replaces 15400-PFB-004replaces 15400-ZW4-003replaces 15400-PJ7-015	—	Spin-on cartridge for every generation. The catalogues list -PJ7-015 (first A), -ZW4-003 (A1, A2), -PFB-004 or -PFB-007 (A4) and -PFB-014 (D, DK2, DK4); all now lead to -ZZ3-003.
Drain plug gasket	`90601-ZE2-000`^20,21,22,23	—	12 mm washer for the oil drain bolt, the same on A and D engines; fit a new one at every oil change (23 N·m).
Spark plug	`98069-57756`^25,26,27	NGK `DR7EB`^24,23	BF40D/BF50D: Denso X22ESR-UB under Honda’s number; 3 per engine, gap 0.6–0.7 mm, 18 N·m.
Spark plug	`DR7EA`^28,29	Denso `X22ESR-U`^28,29	NGK plug for the carburettor BF40A/BF50A only; 3 per engine, gap 0.6–0.7 mm.
Thermostat	`19300-ZW9-003`^30,14,15,16	—	BF40A4/BF50A4 and every BF40D/BF50D; the same thermostat as on many smaller Hondas.
Thermostat	`19300-ZV5-043`^31,19,18,32	—	Earlier carburettor engines: BF40A/BF50A, A1, A2 and AX.
Thermostat gasket	`19351-ZV5-000`^33,14,19	—	Thermostat cover gasket, the same on every A and D engine.
Anode (engine)	`12155-ZV5-010`^{14,15,16,19,34}replaces 12155-ZV5-000	—	Anode in the cooling passage of the cylinder block, listed in every A and D catalogue (on the DK4 under cover 19381-ZZ5-M00).
Anode (engine)	`12155-ZV4-A01`^35,25,36replaces 12155-ZV4-A00	—	BF40D/BF50D and DK2: two anodes in the cylinder head under caps 12150-ZZ5-020. One source (one dealer’s Honda fiche).
Anode (engine)	`12155-ZZ5-010`^26,37,38replaces 12155-ZZ5-000	—	DK4 (from 2017): the two cylinder head anodes have their own number; caps 12150-ZZ5-020 as before. One source.
Anode (lower unit)	`41106-ZW9-000`^{39,40,41,42,23}	—	Two per engine, one on each side of the gear case (D, DK2, DK4); the same anode as on the BF8D to BF30D.
Anode (clamp bracket)	`06411-ZV5-020`^{43,44,45,46,47}replaces 06411-ZV5-010replaces 06411-ZV5-000	—	Anode kit for the stern bracket; the A engines list -000 or -010, now supplied as -020 for all.
Fuel filter (engine)	`16901-ZZ5-003`^48,35,26,23	—	BF40D/BF50D: element in the fuel filter cup with water separator under the cowl (assembly 16900-ZZ5-003). Fit new O-rings 16918-ZZ5-003 and 16919-ZZ5-003, cup 3 N·m.
Fuel filter (engine)	`16910-ZV4-015`^49,50,51	—	BF40D/BF50D: small in-line strainer in the fuel tubing, the same part as on many smaller Hondas.
Fuel filter (engine)	`16911-ZZ5-003`^52,53,54	—	BF40D/BF50D: high-pressure strainer screen inside the vapour separator, with O-ring 16073-ZZ5-003; a dealer job every 2 years or 400 h.
Fuel filter (engine)	`16900-SA5-004`^55,56,57	—	BF40A/BF50A (all carburettor versions): fuel strainer under the cowl.
Timing belt	`14400-ZV5-014`^{58,59,60,61,62}replaces 14400-ZV5-004	—	One belt for every A and D engine (early A catalogues list -004). Tensioner 14510-ZV5-013. Dealer job.
Valve cover gasket	`12391-ZV5-010`^63,26,64,65replaces 12391-ZV5-000	—	Head cover packing, needed for the valve clearance check; the same on A and D engines.
Gear oil plug gaskets	`91301-ZW4-003`^66,40,41,67	—	O-ring 6.9 × 1.45 mm, listed three times with the gear case drain bolt and the two oil check bolts; A4 and all D engines. The earlier A engines use different screws.
Propeller nut	`90301-ZV5-000`^68,69,70	—	16 mm castle nut, the same on every A and D engine; torque depends on the manual edition (see the specifications).
Cotter pins	`90758-ZV5-000`^71,69,70,23	—	4.0 mm split pin for the propeller nut; Honda asks for a new stainless pin every time.
Propeller hardware kit	`90506-ZZ5-C00`^72,69,73,70replaces 90506-ZV5-020replaces 90506-ZV5-010replaces 90506-ZV5-000	—	Propeller thrust washer, fitted grooved side towards the gear case; all older numbers lead here.

Numbers checked against the sources below on 23 October 2026. Always confirm against your serial number and exact type before ordering.

Service intervals

Task	Interval
Oil level check	Before each use^24,23
Engine oil change	Every 100 h or 6 months, first after 20 h or 1 month^24,23
Gear oil change	Every 100 h or 6 months, first after 20 h or 1 month (dealer)^24,23
Oil filter	Every 200 h or yearly (dealer)^24,23
Spark plug	Check, re-gap or replace every 100 h or 6 months^24,23
Fuel filter	Low-pressure filter with water separator: check for water before each use and every 100 h or 6 months, replace every 400 h or 2 years; high-pressure filter: check every 100 h or 6 months, replace every 400 h or 2 years (dealer); clean the fuel tank and its filter every 200 h or yearly^24,23
Hoses & clamps	Fuel line: check before each use; replace every 2 years if necessary (dealer)^24,23
Raw water impeller	Water pump: check every 200 h or yearly (dealer); watch the tell-tale at every start^24,23
Thermostat	Check every 200 h or yearly (dealer)^24,23
Timing belt	Check and adjust every 200 h or yearly (dealer)^24,23
Valve clearance	Check and adjust every 200 h or yearly (dealer)^24,23
Idle speed check	Throttle linkage and idle speed: check and adjust after the first 20 h or month, then every 100 h or 6 months (dealer)^24,23
Anode	Outside anodes: check before each use; anodes inside the engine: check every 200 h or yearly (dealer); replace when worn to about half their size or crumbling^24,23
Propeller	Check the propeller and cotter pin before each use^24,23
Lubrication	Grease after the first 20 h or month, then every 100 h or 6 months; more often in salt water^24,23
Control cables	Shift cable: check and adjust every 100 h or 6 months (dealer); Honda Europe suggests a new cable after about three years if you shift a lot^24,23
Crankcase ventilation	Check the breather tube every 200 h or yearly (dealer)^24,23
Cooling system	Flush with fresh water after every use in salt, muddy or murky water^24,23

Hours or months, whichever comes first. The plan is from Honda’s BF40D/BF50D owner’s manual (Honda Motor Europe, 2026 edition 32ZZ4647); the US 2024 edition lists the same intervals. “Dealer” marks the jobs Honda leaves to a workshop unless you have the tools and the shop manual. The carburettor BF40A/BF50A (2003 manual) follow almost the same plan, without the high-pressure filter and the inside anodes; their plugs are checked every 100 h and replaced every 200 h or yearly.

Specifications

Type	Four-stroke, 3 cylinders in line, overhead camshaft with toothed belt, 2 valves per cylinder; BF40D/BF50D with multi-port PGM-FI injection, BF40A/BF50A with carburettors^74,75,28
Displacement	808 cc (70 × 70 mm)^74,75,24
Power	BF40: 29.4 kW (40 PS), BF50: 36.8 kW (50 PS) at the propeller shaft (ISO 8665); Honda US rates them at 40 hp at 5,500 rpm and 50 hp at 6,000 rpm^24,74
Full-throttle range	BF40 5000–6000 rpm; BF50 5500–6000 rpm^24,28
Idle speed	BF40D/BF50D 850 ± 50 rpm; BF40A/BF50A 950 ± 50 rpm^23,28
Injection	BF40D/BF50D: PGM-FI with a mechanical low-pressure pump, an electric high-pressure pump in the vapour separator and a fuel filter with water separator under the cowl^23,24,54
Ignition	BF40D/BF50D: full-transistor battery ignition; BF40A/BF50A: CDI^24,76
Fuel	Unleaded petrol, RON 91 (AKI 86) or higher; separate 25 l tank²⁴
Cooling	Raw-water cooled with thermostat; impeller pump in the lower unit, tell-tale check hole, fresh-water flush port; exhaust through the propeller hub^24,74
Engine oil capacity	BF40D/BF50D: 2.0 l, 2.1 l with filter change; BF40A/BF50A: 2.0 l, 2.4 l with filter change^24,28
Engine oil grade	BF40D/BF50D: SAE 10W-30, API SG to SL (the first 2009 manuals recommend SAE 5W-30); BF40A/BF50A: SAE 5W-30, API SG or later^24,77,28
Gear oil capacity	0.41 l (the 1994 BF40A/BF50A manual gives 0.5 l)^24,28,76
Gear oil grade	SAE 90 hypoid gear oil, API GL-4 (BF40A/BF50A: GL-4 or GL-5)^24,28
Spark plug	BF40D/BF50D: NGK DR7EB or Denso X22ESR-UB; BF40A/BF50A: NGK DR7EA or Denso X22ESR-U; 3 per engine, gap 0.6–0.7 mm^24,28
Valve clearance (cold)	Cold: intake 0.15 ± 0.02 mm, exhaust 0.23 ± 0.02 mm (A and D)^23,28
Tightening torques	Current manuals: spark plugs 18 N·m, oil drain bolt 23 N·m, fuel filter cup 3 N·m, propeller castle nut 20 N·m and on to the next slot (never above 82 N·m); the 2009 editions give the castle nut 1 N·m with a limit of 34–35 N·m^23,24,77,78
Alternator	BF40D/BF50D: belt-driven 22 A alternator, 12 V / 17 A charging; BF40A/BF50A: 12 V / 10 A^74,24,28
Gearbox	F-N-R dog clutch, 2.08:1^74,24
Shaft length	Transom height at 12° transom angle: S 416 mm, L 521 mm, Y 556 mm and X 622 mm (Y and X: BF50D only); BF40A/BF50A: L 521 mm, X 622 mm^24,28
Dry weight	BF40D/BF50D with propeller: 96–103 kg depending on shaft, tiller or remote control and tilt system; BF40A/BF50A: 87.5–96 kg^24,29,28
Tilt	Trim −4° to +12°, tilt up to 63° (at 12° transom angle); power trim/tilt or gas-assisted tilt depending on version^24,74
Serial number prefixes	Frame serial number: BF40A BAYL, BAYS, BAYU; BF50A BAZJ, BAZL, BAZS, BAZU; BF40D BBDJ; BF50D BBEJ^79,80,24
Years built	BF40A/BF50A: oldest Honda owner’s manual from 1994, last US edition 2006; BF40D/BF50D: from March 2008 (Japan) and mid-2008 (US), restyled as DK4 in 2017, still in production^{76,28,75,81,82,83,74}

Good to know

Honda’s catalogue lists two impeller pump kits for every A and D engine, 06192-ZV5-023 and 06193-ZV5-040, without saying what is in them, and a UK Honda dealer sells the first only for the carburettor models and the second for the 2008+ fuel-injected engines. If in doubt, order the impeller 19210-ZV5-003, the same in every generation, with the gaskets you need, or ask a dealer with your serial number.^7,9,10,12,1
Measure the oil rather than going by an old figure: the BF40D/BF50D take 2.0 l, 2.1 l with a new filter, while the carburettor A models take 2.4 l with filter. The current manuals ask for SAE 10W-30; the first 2009 editions still said 5W-30.^24,77,28
The propeller nut torque changed between manual editions: today Honda gives 20 N·m and then on to the next slot, never above 82 N·m, while the 2009 manuals say just snug (1 N·m) with a limit of 34–35 N·m. Follow the manual for your serial number and fit a new 4 mm cotter pin (90758-ZV5-000) every time.^{24,23,77,78,71}
On the fuel-injected engines, look at the fuel filter under the cowl before every trip: a red ring float in the cup shows how much water has collected, and water or dirt there causes loss of power and hard starting. Fit new O-rings when you open the cup and tighten it to only 3 N·m.^23,26
Before laying the engine up, either drain the vapour separator or add stabiliser and run the engine for ten minutes, and cover the oxygen sensor and the timing belt before you spray corrosion inhibitor under the cowl — both are in Honda’s storage instructions.²³
The fuel-injected engines carry two anodes on the gear case and one on the stern bracket, plus small anodes in the cooling passages (the catalogue lists two in the cylinder head and one in the block). Honda wants the inside ones checked every 200 h or yearly; replace any anode worn to about half its size or crumbling.^23,26,14,40

Videos & how-tos

Links to YouTube, nothing embedded. The maker’s own channel comes first; the rest are channels we found clear and correct for this model.

Engine oil change on a Honda outboard (Honda’s general DIY guide) Video Honda · maker’s channel · EN · 3 min
Annual maintenance on a 2018 Honda BF50: oils, spark plugs, propeller and greasing Video Shuswap Outdoors · EN · 27 min
Fuel filters on a 2018 Honda BF50: water separator, in-line and high-pressure filter Video Shuswap Outdoors · EN · 16 min
Thermostat, water pump and fuel filters on a 2023 Honda BF50 Video Jacob Slupecki · EN · 12 min

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Sources

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