Yamaha · Outboard

Yamaha F25

The F25 with model code 6FM has been Yamaha’s 25 hp portable four-stroke since late 2016: a 432 cc in-line twin with a belt-driven overhead camshaft and fuel injection that runs without a battery, so even the pull-start versions are injected. At 56–64 kg it is about 20 kg lighter than the 498 cc carburettor F25D it replaced (also built as the high-thrust FT25F), which had in turn followed the carburettor F25A; both older engines take a different pump kit, impeller, thermostat and fuel filter. Europe sold it as the F25G and since 2026 as the F25MHC, F25WHC, F25EC and F25C, while the US and Australia use names ending in C such as F25SMHC or F25LWTHC; there an A at the end (F25LMHA) marks the old carburettor engine. With tiller or remote control, manual tilt or power trim and tilt and a 15 or 20 in shaft, it is common on RIBs, larger tenders and small aluminium boats.

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 Yamaha. We host no manuals or drawings — the manufacturer’s copy is the current one.

Owner’s manual F25MHC, F25WHC, F25EC, F25C (6FM-28199-7A, November 2025) Operation manual cdn2.yamaha-motor.eu · PDF · EN · DE · FR · ES
Owner’s manual F25G for model years 2024–2025 (6FM-28199-79, November 2023) Operation manual cdn2.yamaha-motor.eu · PDF · EN · DE
Owner’s manual F25G, first edition (6FM-28199-70-E0, November 2016) Operation manual cdn2.yamaha-motor.eu · PDF · EN
Owner’s manual F20F and F25G (6FM-28199-71-E0, February 2017) Operation manual cdn2.yamaha-motor.eu · PDF · EN
Owner’s manual F20D, F25D, FT25F, the 498 cc predecessor (6BP-28199-75-E0, September 2012) Operation manual cdn2.yamaha-motor.eu · PDF · EN
Yamaha Motor Europe owner’s manual library (outboards, all years and languages) Manual portal yamaha-motor.eu · EN
Yamaha Outboards (US): owner’s manuals by model prefix, shaft length and serial number Manual portal yamahaoutboards.com · EN
Yamaha Outboards (US): 25, 20 and 15 hp portables with the F25 specifications Product page yamahaoutboards.com · EN
Yamaha parts catalogue F25SMHC 2017 (from serial number 6FMK-1000001), all diagrams Parts catalogue outboardbits.com.au · EN
Yamaha parts catalogue F25SMHC 2025 (from serial number 6FMK-1088597), all diagrams Parts catalogue outboardbits.com.au · EN

Wear parts & part numbers

Part	OEM number	Also fits	Note
Water pump repair kit	`6FM-W0078-02-00`^1,2,3,4,5replaces 6FM-W0078-00-00	—	Pump housing 6L2-44311-01-00, cartridge insert 6L2-44322-00-00, outer plate 6FM-44323-01, impeller 6L2-44352-00-00, water-seal damper 6L2-44367-11, O-ring 93210-45161-00, two plates 6L2-44328-00-00, bolts, dowel pins and the Woodruff key. The first kit 6FM-W0078-00-00 was superseded via -01 to -02-00, the one to order now. The F25D and F25A use kit 61N-W0078-11-00 (now 61N-W0078-14), which does not fit.
Raw water pump impeller	`6L2-44352-00-00`^6,2,7,8	—	The same in every F25SMHC catalogue from 2017 to 2025 and inside the pump kit; it is driven by Woodruff key 90280-03024-00. The 498 cc F25D and F25A use 6H4-44352-02-00.
Engine oil filter	`5GH-13440-90-00`^9,10,11,4,12replaces 5GH-13440-61-00replaces 5GH-13440-60-00	—	Spin-on cartridge; oil the O-ring and tighten to 18 N·m. The 2017 catalogue lists -60-00, US service kits contain -61-00, and the 2025 catalogue lists -90, which replaces -20, -60, -61 and -80. The older F25D uses the same 5GH-13440 filter family.
Spark plug	`94702-00418-00`^12,13,10,14	NGK `DPR6EB-9`¹²	Yamaha’s number for the NGK DPR6EB-9. Two per engine, gap 0.8–0.9 mm, 17 N·m. The older F25D and F25A take the same plug.
Fuel filter (engine)	`6D8-WS24A-00-00`^15,16,17,4replaces 6D8-24563-00-00	—	10-micron element of the filter under the cowling (filter assembly 6FM-24560-00-00, cup 6FM-24521-00-00, water-level float 6D8-24469-00-00). The F25D and F25A use element 61N-24563-10-00.
Fuel filter O-ring	`6D8-24564-00-00`^1,16,18	—	O-ring of the filter cup; Yamaha lists it with the element among the scheduled-service parts. One source.
Drain plug gasket	`90430-14M09-00`^19,20,4,12	—	Under the engine oil drain screw 90340-14M06-00; fit a new one at every oil change and tighten the screw to 27 N·m.
Gear oil plug gaskets	`90430-08003-00`^6,10,4,12replaces 90430-08020-00	—	Two per gear oil change, under the drain screw and the level plug (both 90340-08002-00, 7 N·m).
Thermostat	`6FM-12411-00-00`^9,21,22,23	—	Fitted with thermostat seal 6FM-12412-00-00 under the thermostat cover. The F25D and F25A use 6G8-12411-03-00, now 66M-12411-01-00.
Thermostat gasket	`6FM-12414-00-00`^9,10,24,23	—	Gasket of the thermostat cover; also part of the power head gasket kit.
Anode (engine)	`6G8-11325-00-00`^1,9,13,25,12	—	Four small screw-in anodes in the cooling jacket: two in the cylinder head, one in the block and one by the thermostat cover, most of them behind blind plugs 6G8-11197-A0-00 with O-ring 93210-13M63. The manual has the thermostat-cover anode checked every 100 h and those in head and block replaced every 500 h by a dealer. One source.
Anode (lower unit)	`664-45371-01-00`^26,10,27,12	—	The trim tab under the anti-cavitation plate doubles as the external anode; check it every 100 h or yearly and never paint it.
Timing belt	`6FM-46241-00-00`^28,29,30	—	Check every 100 h, replace at 1000 h. The 498 cc F25D and F25A use different belts. One source.
Gasket set	`6FM-W0001-01`^24,31,32replaces 6FM-W0001-00-00	—	Power head gasket kit: cylinder head gasket 6FM-11181-00-00, cylinder gasket 6FM-11351-01, manifold and thermostat-cover gaskets, oil seals and O-rings. One source.
Lower unit seal kit	`6FM-W0001-21`³³replaces 6FM-W0001-20-00	—	Lower unit gasket kit, listed for all US and Australian F25 C models; it replaces 6FM-W0001-20-00. One source.
Propeller hardware kit	`91490-30025-00`^26,34,12replaces 91490-30022-00	—	Cotter pin for castle nut 90171-14013-00 (34 N·m); fit a new one every time the propeller has been off. One source.
Propeller	`664-45941-01-00`^34,35,12replaces 664-45941-01-EL	—	3-blade aluminium, 9⅞ × 9 in, mark F; the propeller in the 2025 F25SMHC catalogue. Pick the pitch that lets the engine reach 5000–6000 rpm at full throttle. One source.
Propeller	`664-45949-02-00`^26,36	—	3-blade aluminium, 9⅞ × 13 in, mark F; the propeller in the 2017 F25SMHC catalogue. One source.

Numbers checked against the sources below on 12 October 2026. Always confirm against your serial number and exact type before ordering.

Service intervals

Task	Interval
First service	After the first 20 h or 3 months: change engine oil and gear oil; check the fuel filter, fuel lines, spark plug caps and leads, propeller, nut and cotter pin; grease the greasing points¹²
Engine oil change	First after 20 h or 3 months, then every 100 h or yearly¹²
Oil filter	Every 100 h or yearly¹²
Gear oil change	First after 20 h or 3 months, then every 100 h or yearly¹²
Spark plug	Check, clean or replace every 100 h or yearly; plug caps and leads at 20 h, then every 100 h¹²
Fuel filter	Check and clean or replace at 20 h, then every 100 h or yearly, together with the fuel lines¹²
Raw water impeller	Impeller and pump housing: check every 100 h or yearly, replace every 300 h or 3 years (dealer)¹²
Thermostat	Check every 100 h or yearly, replace if needed¹²
Anode	External anode (trim tab) and the anode at the thermostat cover: check every 100 h or yearly; anodes in cylinder head and block: replace every 500 h or 5 years (dealer)¹²
Timing belt	Check every 100 h or yearly; replace at 1000 h¹²
Valve clearance	Check and adjust every 500 h or 5 years¹²
Fuel pump	Check every 300 h or 3 years, replace if needed¹²
Lubrication	Greasing points at 20 h, then every 100 h or yearly; propeller, nut and cotter pin checked at the same times¹²
Exhaust	Exhaust guide and exhaust manifold: check every 1000 h¹²
Throttle body	Every 100 h or yearly¹²

Hours or months, whichever comes first, from Yamaha Motor Europe’s owner’s manual 6FM-28199-7A-E0 (first edition November 2025, for the F25MHC, F25WHC, F25EC and F25C), which assumes about 100 h of use a year and regular flushing. Under severe use (long running at full throttle or at low speed, too little warm-up, frequent starts, shifts or changes of load) Yamaha halves every interval. This edition also adds a check and cleaning of the throttle valve (throttle body) every 100 h, which the earlier F25G charts do not list.

Specifications

Type	Four-stroke, SOHC with toothed-belt drive; electronic fuel injection, battery-less on pull-start models¹²
Cylinders	2 in line, 4 valves (2 per cylinder)¹²
Displacement	432 cc (26.4 cu in)^12,37
Bore × stroke	65.0 × 65.1 mm^12,37
Compression ratio	9.3:1³⁷
Power	18.4 kW (25 hp) at the propeller shaft; Yamaha US: 25 hp at 5500 rpm^12,37
Full-throttle range	5000–6000 rpm¹²
Idle speed	850–950 rpm in neutral¹²
Ignition	TCI (transistor-controlled); the first F25G manual of 2016 and Yamaha US call it CDI^12,38,37
Spark plug	NGK DPR6EB-9, 2 per engine¹²
Spark plug gap	0.8–0.9 mm¹²
Valve clearance (cold)	Intake 0.15–0.25 mm, exhaust 0.25–0.35 mm¹²
Engine oil capacity	1.1 l with filter change, 1.0 l without; wet sump^12,37
Engine oil grade	Yamalube 4 or another four-stroke outboard oil, SAE 10W-30, 10W-40 or 5W-30, API SG or higher; the 2026 manual also allows SAE 15W-40, 20W-40 or 20W-50, API SH or higher. Earlier manuals and Yamaha US name Yamalube 4M FC-W^12,38,37
Gear oil capacity	0.370 l (370 ml)¹²
Gear oil grade	Yamalube outboard gear oil or hypoid gear oil SAE 90, API GL-4; fill through the drain hole until it runs out of the level hole¹²
Gearbox	Forward, neutral, reverse; propeller mark F¹²
Gear ratio	2.08:1 (27/13) in all European owner’s manuals; Yamaha US’s spec page gives 2.00:1^12,38,37
Tilt	Manual tilt (F25GMH, F25GWH, F25GE; F25MHC, F25WHC, F25EC) or power trim and tilt (F25GET, F25C)^12,39
Alternator	Up to 16 A; to charge a battery the engine needs a rectifier or rectifier regulator and a lighting coil, available as an option for models without^12,37
Battery	Electric start: 347–411 A CCA (EN), 40 Ah (20HR/IEC)¹²
Dry weight	With aluminium propeller, 15 in shaft: 56 kg (F25GE, F25EC), 57 kg (F25GMH, F25MHC), 60 kg (F25GWH, F25WHC), 63 kg (F25GET, F25C); 20 in shaft 58–64 kg^12,39
Shaft length	S 15 in (transom height 424 mm), L 20 in (551 mm); power trim and tilt models 426 mm (S) and 553 mm (L)¹²
Fuel	Unleaded petrol, at least 90 RON, up to 10 % ethanol; Yamaha US: 87 octane plus an external 10-micron fuel/water separating filter^12,37
Cooling	Raw water with thermostat; rubber impeller pump on the drive shaft, cooling-water pilot hole and a garden-hose flushing connector on the bottom cowling¹²
Tightening torques	Spark plug 17 N·m, oil drain screw 27 N·m, oil filter 18 N·m, gear oil plugs 7 N·m, propeller nut 34 N·m¹²
Versions	MH = tiller, pull start; WH = tiller, pull and electric start; E = remote control, electric start; ET (F25GET) and the 2026 F25C = remote control with power trim and tilt; S or L = 15 or 20 in shaft, at the end in Europe (F25GMHS, F25GETL) and after F25 in the US (F25SMHC, F25LWHC)^12,38,1
Models	Model code 6FM (European owner’s manuals 6FM-28199, US and Australian serial numbers from 6FMK-1000001). Europe: F25GMHS/L, F25GWHS/L, F25GES/L and F25GETL until 2025, F25MHC, F25WHC, F25EC and F25C from 2026. US and Australia: F25SMHC, F25LMHC, F25SWHC, F25LWHC, F25SWTHC, F25LWTHC, F25SC, F25LC, F25SWC, F25LWC, F25SWTC and F25LWTC; there an A suffix (F25LMHA) marks the older carburettor engine^1,12,38
Predecessor	F25D, F20D and the high-thrust FT25F (498 cc, carburettor, owner’s manual 6BP-28199); before them the carburettor F25A⁴⁰
Years built	Since late 2016 (first European F25G manual: November 2016); still current in 2026 as the F25MHC, F25WHC, F25EC and F25C^38,12

Good to know

One engine, many names: a European F25G (2017–2025), an F25MHC, F25WHC, F25EC or F25C (2026) and a US or Australian F25SMHC, F25LWHC and so on are all the 432 cc engine with model code 6FM and take the same service parts. The heavier F25D and F25A are different engines, so read the model code on the serial label (6FM, or 6BP and 65W on the old ones) before you buy a pump kit, thermostat or fuel filter.^1,12
For an oil change, let the engine idle for 5–10 minutes, stop it and wait another 5–10 minutes, then suck the oil out through the dipstick guide with an oil changer, or open the drain screw and fit a new gasket (27 N·m). It holds only 1.0 l, or 1.1 l with a new filter, so measure the oil instead of pouring from the bottle and check the dipstick again.¹²
After a trip in salt water, flush with the engine off: screw a garden hose onto the connector on the bottom cowling and let fresh water run through for about 15 minutes. Then screw the connector back on firmly, or cooling water escapes there and the engine overheats.¹²
The camshaft is driven by a toothed belt. Yamaha wants it checked every 100 h and replaced at 1000 h, which a hard-worked club or charter tender reaches sooner than you might think.¹²
The fuel filter under the cowling has a cup with a water-level float. Look at it at every service: water or dirt in the cup means the element (6D8-WS24A-00-00) needs cleaning or replacing. Yamaha US also recommends an external 10-micron fuel/water separating filter between tank and engine.^15,37
Pull-start models run on fuel injection that needs no battery. If you want to charge a battery from the engine and yours has no rectifier regulator, have the optional one (6FM-81960-10-00) fitted first; the manual says a battery must not be connected without it.^41,12

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.

100-hour service at home on a 2017+ Yamaha F25: oil, filter, plugs, gear oil and water pump Video FloBass · EN · 24 min
Oil change on a 2019 Yamaha F25 Video 1 BentLoomis · EN · 12 min
Removing the flywheel and replacing the timing belt on a Yamaha F25 (432 cc) Video Yamaha Outboard Motor Magician · EN · 9 min

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Sources

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