Suzuki DF4A vs DF5A vs DF6A: What's Different, What's the Same and Which Portable to Buy

The Suzuki DF4A and DF6A are one engine with two ratings. Their shared owner's manual (99011-97L60-03B, 2020–2024 models) gives both a single specification block: one cylinder, 138 cm³ (8.4 cu in), 60.4 × 48.0 mm (2.38 × 1.89 in) bore and stroke, digital CDI ignition, 0.7 L of engine oil, a 1.0 L built-in fuel tank, the same NGK CPR6EA-9 spark plug and the same 1300 ± 50 r/min idle. What separates them is the rating: 2.9 kW (4 PS) against 4.4 kW (6 PS), a full-throttle operating range of 4000–5000 r/min against 4750–5750 r/min, and an over-revolution limit of 5100 against 5850 r/min. The other difference is fuel: the manual lists the fuel connector for a separate tank, and the priming bulb, as DF6A-only items, so a DF4A runs on its built-in tank alone.

The DF5A sits between them, and the manuals we have say less about it. The 2020–2024 owner's manual names only DF4A and DF6A. Suzuki's 2025 maintenance manual lists "DF4A/5A/6A" from model year 2017 as one row, with the same valve lash, compression, oil pressure and thermostat for all three, so the DF5A shares the service figures; its own rated output and full-throttle range are not stated in the manuals we have. Boat Max Online currently sells the DF4AS5 (short shaft) and the DF6AS5 (short), DF6AL5 (long) and DF6ASW5 (short, white), and does not list a DF5A at the moment. The older carbureted DF4, DF5 and DF6 (2002–2015 model years) are a different engine, covered in a table near the end.

Spec table: DF4A vs DF5A vs DF6A

Figures are from the DF4A/DF6A owner's manual for 2020–2024 models. The DF5A column shows only what the manuals we have state for it.

Everything else in the owner's manual specification is shared by the DF4A and DF6A:

Service data for DF4A, DF5A and DF6A (2017 on)

The one row in Suzuki's 2025 maintenance manual that names all three; it is the dealer's checking data and it is identical across them.

Valve lash and the engine oil filter are asterisk items in the owner's manual's maintenance chart, which Suzuki recommends only an authorized Suzuki marine dealer or a qualified mechanic perform. Intervals, part numbers and the oil change are on our DF4A/DF5A/DF6A service guide; the rest of the range is on the oil capacity chart and the spark plug chart.

Fuel: the built-in tank and the DF6A separate-tank option

Both carry a 1.0 L (0.26/0.22 US/Imp gal) built-in tank under the cover, with an air-vent screw on the cap: closed for transportation, open for operation and cap removal. On the DF4A that tank is the only fuel supply. The DF6A adds a fuel connector on the engine side for an optional separate tank, with a priming bulb as an optional part. A fuel cock lever picks the source: left, fuel flows from the built-in tank; right, fuel flows to the carburetor from the separate tank. Right is also the off position for the built-in tank when you stop or tilt the motor.

Two rules when you switch tanks on a DF6A. Running on the built-in tank, disconnect the separate tank's line from the engine-side connector, or fuel from the built-in tank may not flow correctly. When the separate tank runs dry, disconnect its line first, fill the built-in tank, wait briefly, then turn the lever left. Suzuki's genuine portable tanks have a semi-auto air vent; loosen and retighten the cap once before connecting the hose to relieve pressure. Which tank and hose fitting you need is on our portable fuel tank and hose fittings page.

The fuel spec is the same for both: alcohol-free unleaded, minimum 87 pump octane, gasohol allowed up to 10% ethanol. Gasoline left in the tank for long periods produces varnish and gum that can damage the engine.

Handling: tilt, shallow water, carrying and transport

Tilt and shallow water

Both have manual tilt: a tilt up lock arm holds the motor fully tilted up or in one of two shallow water positions, and a tilt pin sets trim. The manual's sequence before tilting: shift into neutral, turn the fuel cock lever right (off) and tighten the air vent screw on the filler cap, then lift by the handle on the back of the motor cover until the lock arm catches; on a DF6A on a separate tank, disconnect the fuel line and fit the connector cap first. Lower the motor before reopening the vent screw, never lift by the throttle grip, and keep your hands away from the mounting bracket and from under the motor.

In normal trim, shifting into reverse locks the motor automatically so thrust cannot lift it. In a shallow water position that lock does not work, so reverse thrust, rapid deceleration or striking an underwater object can lift the motor out of the water and injure someone: use it only at very low speed, keep the water intakes submerged with water spraying from the discharge hole, and release it in deep water. The full procedure is on our portable tilt, trim and shallow water drive page.

Carrying and transporting

To take the motor off the boat: engine stopped, fuel cock lever right, tank cap and air-vent screw tight, fuel hose off and the connector capped on a DF6A, carburetor drained through its drain screw. Remove the mounting bolts, loosen the clamp screws, lift the motor off and stand it vertically so the lower unit drains. Carry it by the hand grip and the rear handle in the engine lower cover.

Transport it vertically with the clamp bracket secured by its two clamp screws (never on a display stand), or horizontally on a case protector with the port, starboard or front side down, and only after the fuel and cooling water have drained, because water can enter the cylinder through the exhaust port. Never let the lower unit sit higher than the powerhead. On a trailer, keep the motor in the running position unless ground clearance forces a tilt, and then support it with a transom saver bar, never the tilt up lock arm, which towing can release. Store it upright in a dry, well-ventilated place at a constant temperature. The rest of the range is on our transport and trailering guide.

If the recoil starter fails

Both use a recoil starter with a neutral start interlock, so it cannot be pulled in gear. The manual's emergency rope start means removing the recoil starter, fuel tank bolts, air vent duct and cooling fan bolts before the rope goes on the pulley, and in that mode start-in-gear protection does not work: the boat can start off unexpectedly if the shift lever is not in neutral. Keep hands clear of the ignition coil and plug lead, and have the starter repaired as soon as possible rather than running on the emergency procedure.

Which one to buy

• Dinghy or tender for short runs: the DF4A does the job on its built-in tank and is the simpler motor, with no connector, hose or primer bulb to manage. Boat Max Online lists it in short shaft only, so measure the transom before you order.
• Tender or inflatable that goes further: the DF6A is the one with a fuel connector, so you can run a separate tank and keep the 1.0 L built-in tank as a reserve. On a DF4A, 1.0 L is all you carry.
• Sailboat auxiliary or a deeper transom: the long shaft exists only on the DF6A in the store's current listings (DF6AL5). The manual warns that a motor mounted too high on the transom makes the propeller slip, wasting power or overheating, so measure first.
• Hull with a horsepower limit: if the capacity plate says 4 hp, that settles it. If it allows 6, the DF6A is the same engine with the higher rating and the same maintenance items.
• Weight: the owner's manual we have does not print weights for either motor, so we will not guess at the difference. The older DF4/DF5/DF6 service manual printed one weight for that whole family (table below).

Whichever you choose, prop it so the engine reaches its own full-throttle range loaded: smaller loads generally take a larger-pitch propeller, larger loads a smaller pitch. If the over-revolution system activates the motor runs rough and you must reduce speed immediately; the manual names cavitation in hard turns, a slipping prop bush or worn blades, and too much trim as the causes.

Older DF4, DF5 and DF6 (2002–2015): a different engine

Before the "A" models, Suzuki sold a carbureted DF4, DF5 and DF6 with the same 138 cm³ displacement but a different bore and stroke, a bigger built-in tank and different service figures. The source is the DF4/DF5/DF6 service manual (99500-91J03-01E, compiled on the 2002 model, revised June 2013) and its supplements for serial 110001 and later and 210001 and later; the DF6 was added as a new product redesigned for more power on the basis of the DF4/DF5. If the plate on the clamp bracket has no "A" in the model name, this is your table.

Two cautions. The 2025 maintenance manual prints thermostats by model year for the DF4/5/6 row as a whole, while the service manual splits by serial and model; we show both rather than resolve them. And the older engine's 0.03–0.07 mm valve clearance is not the "A" engine's 0.13–0.17 mm; do not carry a figure across.

Parts for this job

Boat Max Online is an authorized Suzuki, Honda and Yamaha Marine dealer and sells complete Suzuki outboards up to 30 hp, with free shipping on motors and on orders over $149 to the lower 48. The DF4AS5 is in our Suzuki 4 hp motors collection and the DF6AS5, DF6AL5 and DF6ASW5 in Suzuki 6 hp motors. The oil, NGK CPR6EA-9 plug and 17670-91J02 thermostat are the same parts for both; have the model code and serial number from the plate on the clamp bracket ready and we will confirm fitment.

Sources: Suzuki owner's manual for DF4A/DF6A (99011-97L60-03B, 2020–2024 models); Suzuki service manual 99500-91J03-01E for DF4/DF5/DF6 with its supplements; Suzuki 4-Stroke Outboard Maintenance Manual, 2025 edition. Figures are Suzuki's published values; confirm against the manual for your model year and serial number.