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Honda GX390T2 Engine

The Honda GX390T2 is a 0.39 L 1-cylinder 4-stroke engine rated at 3600 rpm, producing up to 11430 kW. It powers generator sets from Honda, including the EB5000, EB6500, EM5000SXK3 and EM6500SXK2. It holds 1.1 L (0.3 gal) of oil.

Also known as: Honda GX390T2

0.389 L

Displacement

Cylinders

3600 rpm

Rated speed

11430 kW

Gross power

On this pageService parts Specs Generator sets Maintenance Filter cross-reference FAQ Service intervals Torque & specs Fluids Procedures Wiring

Service parts for the GX390T2

The cheapest captured merchant offer per filter — see the full cross-reference below for every OEM/aftermarket option.

Air intake

1 required

P822686Air filterfind

Prices captured from merchant listings; some links are affiliate links. Verify against your serial number before ordering.

Engine specifications

Oil capacity	1.1 L
Displacement	0.389 L
Cylinders	1
Aspiration	4-stroke
Rated speed	3600 rpm
Gross power	11430 kW

Generator sets powered by this engine

Honda EB5000Honda EB6500Honda EM5000SXK3Honda EM6500SXK2

How to read your Honda engine serial & model number →

Common problems

Engine will not rev sufficiently
Cause: Engine oil level low
Fix: Inspection: (page 3-3)
Engine lacks power
Cause: Engine oil level low
Fix: Inspection: (page 3-3)
Engine does not start or is hard to start
Cause: Engine oil level low
Fix: Inspection: (page 3-3)
Ignition system troubleshooting — no spark
Cause: Oil level switch faulty
Fix: Check the engine oil level before troubleshooting; Check the oil level switch (page 13-5); Replace the oil level switch (page 13-4)
Engine speed does not stabilize
Cause: Restricted parts
Fix: Disassemble and inspect for restricted parts
Starter motor does not operate
Cause: Battery discharged
Fix: Check the battery condition (page 15-3); Replace with a known-good battery; If the battery runs down again, perform the CHARGING SYSTEM TROUBLESHOOTING (page 2-38)
Engine does not stop when combination switch is turned off
Cause: Combination switch faulty
Fix: Check the combination switch (page 7-7); Replace the combination switch
Engine does not stop when engine oil level is low
Cause: Oil level switch faulty
Fix: Start the engine; Disconnect the oil level switch wire connector (Yellow) terminal, and short the wire harness side to engine ground using a jumper wire; Replace the oil level switch (page 13-4)
No electricity at the AC receptacles
Cause: AC circuit breaker OFF
Fix: Turn the AC circuit breaker ON.
Hard starting — Wet spark plug
Cause: Carburetor float valve
Fix: If spark plug gap is correct, clean and dry the electrodes, and then restart the engine; If the engine does not start and the electrodes are wet again, check the carburetor float valve (page 5-12)
Hard starting — No spark
Cause: Ignition system fault
Fix: Perform the IGNITION SYSTEM TROUBLESHOOTING (page 2-15)
Hard starting — No fuel
Cause: Clogged fuel tube, fuel filter, or fuel valve; frozen obstruction in the breather tube in cold weather
Fix: Check for clogged fuel tube, fuel filter, and fuel valve; If the engine is stalled in a cold weather application, check for a frozen obstruction in the breather tube
Hard starting — Engine hard to start
Cause: Clogged carburetor ports, jets, and nozzles; choke valve not closing; control gear box fault
Fix: Disassemble the carburetor to check for clogged ports, jets, and nozzles (page 5-10); Restart the engine; Check the control gear box (page 5-7); Remove the carburetor spacer (page 5-4) and check whether the choke valve is closed when pulling the recoil starter
Hard starting — Does not crank
Cause: Recoil starter hard to pull when installed on the engine
Fix: If the recoil starter operates correctly when removed but is hard to pull when installed on the engine, check the decompressor operation of the camshaft (page 13-12); If the recoil starter operates correctly when removed but cannot be pulled when installed on the engine, disassemble the engine and repair or replace the faulty part(s) (page 13-2)
Hard starting — Compression is too low
Cause: Air leakage from the engine
Fix: Check the valve clearance (page 3-9), and then perform the cylinder compression test (page 11-5); If the cylinder compression is too low, perform a leak-down test; If there is air leakage from the engine, check the following: –Valve spring free length (page 11-7) –Valve seat width (page 11-6) –Valve face irregularly worn (page 11-7) –Decompressor operation (page 13-12) –Piston ring side clearance (page 13-8) –Piston ring width (page 13-8) –Piston ring end gap (page 13-8) –Piston skirt O.D. (page 13-6) –Cylinder sleeve I.D. (page 13-6)

Compiled from service & troubleshooting documentation across every generator set that uses the Honda GX390T2.

Maintenance schedule

Item	Spec	Capacity	Part #	Interval
Air filter	Clean in warm soapy water or non-flammable solvent, allow to dry, dip in clean engine oil and squeeze out excess		46449	1000 hr	eBay $63.74
Fuel filter	Honda OE		H34897-AF000	100 hr	Amazon eBay
Oil filter	Change		H34896-AF000	300 hr	Amazon eBay
Battery	12V, 7.5Ah		H34896-AB000	1000 hr	Amazon eBay
Belt	Honda OE		H34892-AF000	500 hr	Amazon eBay
Coolant	Honda Coolant	1.6 L	—	300 hr
Oil	SAE 10W-30, API service category SJ or later (or equivalent)	1.25 L	—	300 hr
Spark plug	Replace		H34896-AP000	1800 hr	Amazon eBay

Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.

Service intervals

Item	Action	Hours	Months	Notes
Engine oil	Change	300 hr	12 mo	First service — First month or 20 hrs
Air cleaner	Clean	100 hr	6 mo	Service more frequently when used in dusty areas (1)
Sediment cup	Clean	100 hr	6 mo	Page 58
Spark arrester	Clean	300 hr	12 mo	Must be serviced every 100 hours to maintain its efficiency
Spark plug	Adjust	300 hr	12 mo	Readjust — every 6 months or 100 Hrs
Fuel tank and filter	Clean	300 hr	12 mo	(2)
Fuel tank and strainer	Clean	300 hr	12 mo	(2) Every year or 300 Hrs
Spark plug	Replace	300 hr	12 mo	Every year or 300 Hrs (page 69)
Valve clearance	Adjust	300 hr	12 mo	Check-adjust every year or 300 Hrs; by servicing dealer (2)
Combustion chamber	Clean	1000 hr		After every 1,000 hrs
Canister	Check		24 mo	Every 2 years (2)
Charge tube	Check		24 mo	Every 2 years (2)
Fuel line	Replace		24 mo	Every 2 years (Replace if necessary)
Fuel tube	Check		24 mo	Every 2 years (replace if necessary) (2)
GFCI receptacle	Test		1 mo	Once each month; test before each use if generator is stored outside unprotected
Purge tube	Check		24 mo	Every 2 years (2)

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Service specifications

Type	Item	Value	Unit	Condition
Clearance	Float height	13.2	mm
Gap	Ignition coil air gap	0.2 – 0.6	mm
Gap	Spark plug electrode gap	0.028–0.031 in (0.7–0.8 mm)	mm
Gap	Spark plug gap	0.028 - 0.031	in
Gap	Spark plug gap	0.028-0.031	in
Gap	Spark plug gap	0.028–0.031	in (0.7–0.8 mm)
Gap	Spark plug gap	0.7 - 0.8	mm
Gap	Spark plug gap	0.70 – 0.80	mm
Gap	Spark plug gap	0.70-0.80	mm
Other	Compression ratio	8.2:1
Other	Spark plug installation (new plug)	1/2	turn after seating to compress washer	new spark plug
Other	Spark plug installation (reused plug)	1/8 - 1/4	turn after seating to compress washer	reinstalling a used spark plug
Pressure	Cylinder compression	1.29	MPa	at 1,400 min-1 (rpm)
Pressure	Cylinder compression	1.31	MPa	at 1,400 min-1 (rpm)
Resistance	CT sensor resistance	18 ±2	Ω
Resistance	Spark plug cap resistance	7.5 – 12.5	kΩ
Speed	Auto Throttle idle speed	2,300 ± 100	min-1 (rpm)
Speed	Engine speed	3,600	rpm
Speed	Engine speed protection limit (DAVR self-diagnosis)	4140	rpm	abnormal voltage/speed sustained longer than 3 seconds
Speed	Maximum engine speed	3,600 ± 100	min-1 (rpm)
Torque	Air cleaner case bolt	5.4	N·m
Torque	Carburetor mount nut	8.5	N·m
Torque	Connecting rod special bolt	14	N·m
Torque	Control panel mount bolt	27	N·m
Torque	Crankcase cover bolt	24	N·m
Torque	Cylinder head bolt	35	N·m
Torque	Engine mount nut	34	N·m
Torque	Exhaust pipe nut	24	N·m
Torque	Fan cover stud bolt	23	N·m
Torque	Fan cover stud bolt mounting nut	40	N·m
Torque	Flywheel special nut	128	N·m
Torque	Flywheel special nut	170	N·m
Torque	Front housing bolt	24	N·m
Torque	Fuel meter screw	4	N·m
Torque	Fuel valve nut	23	N·m
Torque	Generator cooling fan screw	4.8	N·m
Torque	Handle installation	17–22 lbf·ft (24–29 N·m, 2.4–3.0 kgf·m)	N·m
Torque	Handle installation flange bolts	19.5 lbf·ft (26.5 N·m, 2.7 kgf·m)	lbf·ft
Torque	Hanger kit flange bolts	19.5 lbf·ft (26.5 N·m, 2.7 kgf·m)	lbf·ft
Torque	Hanger kit installation	17–22 lbf·ft (24–29 N·m, 2.4–3.0 kgf·m)	N·m
Torque	Oil drain bolt	22.5	N·m
Torque	Oil drain plug (12×15 mm)	16.3 lbf·ft (22.1 N·m, 2.25 kgf·m)	lbf·ft
Torque	Oil drain plug (12×15 mm)	16.6 lbf·ft (22.5 N·m, 2.25 kgf·m)	N·m
Torque	Rear housing cover bolt	9.8	N·m
Torque	Rocker arm pivot adjusting nut	10	N·m
Torque	Rocker arm pivot special bolt	24	N·m
Torque	Rotor bolt	44	N·m
Torque	Rubber mount nut	24	N·m
Torque	Spark plug	13.0 lbf·ft (17.7 N·m, 1.8 kgf·m)	lbf·ft
Torque	Spark plug	13.3 lbf·ft (18 N·m, 1.8 kgf·m)	N·m
Torque	Spark plug	18	N·m
Torque	Spark plug tightening (new plug)	1/2 turn after the spark plug seats	turn	new spark plug
Torque	Spark plug tightening (used plug)	1/8 - 1/4 turn after the spark plug seats	turn	reinstalling a used spark plug
Torque	Wheel kit flange bolts	19.5 lbf·ft (26.5 N·m, 2.7 kgf·m)	lbf·ft
Torque	Wheel kit installation	17–22 lbf·ft (24–29 N·m, 2.4–3.0 kgf·m)	N·m
Valve clearance	Valve clearance EX	0.20 ± 0.02	mm
Valve clearance	Valve clearance EX	0.20±0.02	mm	cold
Valve clearance	Valve clearance EX	0.20±0.02 mm	mm	cold
Valve clearance	Valve clearance IN	0.15 ± 0.02	mm
Valve clearance	Valve clearance IN	0.15±0.02	mm	cold

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Recommended fluids

Fluid	Grade	Standard	Capacity	Notes
Engine oil	SAE 10W-30	API service category SJ or later (or equivalent)	1.1 L	Maximum oil capacity 1.2 US qt (1.1 L); 4-stroke automotive detergent oil; other viscosities per ambient temperature chart
Engine oil	SAE 10W-30 (other viscosities per ambient temperature chart)	API service classification SJ or higher	1.1 L	Non detergent and 2-stroke oils are not recommended
Fuel	Regular unleaded gasoline	pump octane rating 86 or higher
Fuel	Regular unleaded gasoline, pump octane rating 86 or higher	No more than 10% ethanol (E10) or 5% methanol by volume	23.5 L	Fuel tank capacity 6.21 US gal (23.5 L)
Fuel	Unleaded gasoline, pump octane number (R+M)/2 of 86 or higher, or research octane number of 91 or higher		17.0 lit	Fuel tank capacity 17.0 lit (4.5 US gal); do not fill above UPPER LEVEL line; max 10% ethanol; never use methanol above 5%; never use stale or contaminated gasoline or an oil/gasoline mixture
Fuel	Unleaded gasoline, pump octane rating 86 or higher		17.0 L	Fuel tank capacity 17.0 L (4.50 US gal, 3.74 Imp gal); up to 10% ethanol, 5% methanol, or 15% MTBE
Fuel	unleaded gasoline, pump octane rating 86 or higher		17.0 L	Do not fill above the shoulder of the fuel strainer; oxygenated fuels allowed up to 10% ethanol, 15% MTBE, 5% methanol by volume
Grease	Marine grease	water resistant urea based grease
Grease	Multi-purpose grease	NLGI #2 or equivalent		Lithium based multi-purpose grease
Other	Automatic transmission fluid	ATF

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Procedures

GFCI Operation Check (System ①) diagnostic

⚠ A faulty GFCI system will not provide proper protection against electric shock.

⚠ If the GFCI system fails the test, the generator must be repaired by an authorized Honda servicing dealer before use.

Unplug all tools and appliances from the generator.
Start the engine.
Turn OFF the Auto Throttle switch.
Turn the AC circuit breaker to the ON position.
Press the TEST button: the RESET button should pop out and the AC circuit breaker should switch to OFF.
Press the RESET button: it should stay in, flush with its base plate.
With the RESET button in and the engine running, turn the AC circuit breaker to ON; it should remain ON.

GFCI Operation Check (System ②) diagnostic

⚠ If the red indicator starts to blink continuously, contact an authorized Honda generator dealer.

Unplug all tools and appliances from the generator.
Start the engine.
Turn OFF the Auto Throttle switch.
Turn the AC circuit breaker to the ON position; the green indicator should light continuously.
Press the TEST button: the RESET button will pop out and the green indicator will go off.
Press the RESET button: the green indicator will light continuously.

2 Wheel Kit Installation installation

Install the two wheels on the axle shaft.
Install the axle assembly on the generator using four bolts and nuts.
Install the two stands using four bolts and nuts.
Install right and left handles on the generator upper frame using brackets and six bolts.

2-Wheel Kit Installation installation

Install the two wheels on the axle shaft.
Install the axle assembly on the generator using four bolts and nuts.
Install the two stands using four bolts and nuts.
Install right and left handles on the generator upper frame using brackets and six bolts.

4 Wheel Kit Installation installation

⚠ Install the shaft with the wheel stopper facing the engine side.

Install the four wheels on the axle shaft.
Install the axle assembly on the generator using four bolts and nuts.

4-Wheel Kit Installation installation

⚠ Install the shaft with wheel stopper facing engine side.

Install the four wheels on the axle shaft.
Install the axle assembly on the generator using four bolts and nuts.

4-Wheel Kit Installation (optional parts) installation

⚠ Install the shaft with wheel stopper facing engine side.

Install the four wheels on the axle shaft.
Install the axle assembly on the generator using four bolts and nuts.

Handle Installation installation

⚠ Do not add fuel or oil before tipping the generator.

Tools: 12 mm wrench (2), pliers

Install the handle holder assembly on the generator upper frame using the 8×18 mm flange bolts.
Install the handle assembly on the upper frame pipe using 8×16 mm flange bolts, handle bush A, handle bush B, and handle lower bracket.
Torque to 19.5 lbf·ft (26.5 N·m, 2.7 kgf·m).
Check that the handle folds smoothly and does not hang down by its own weight.

Hanger Kit Installation installation

Tools: 12 mm wrench (2)

Position the hanger at the generator's balance point.
Fit the end tabs of the hanger through the bracket slots.
Bolt the brackets to the hanger and tighten securely.
Torque to 19.5 lbf·ft (26.5 N·m, 2.7 kgf·m).

Wheel Kit Installation installation

Tools: 12 mm wrench (2), pliers

Install the two stands on the under frame using four 8×16 mm flange bolts.
Install the two wheels on the axle shaft using the washers and split pins; bend the pins.
Install the axle assembly using four 8×16 mm flange bolts and 8 mm flange nuts.
Torque to 19.5 lbf·ft (26.5 N·m, 2.7 kgf·m).

Air Cleaner Check/Cleaning maintenance

⚠ Excess oil will restrict air flow and may cause engine to smoke at startup.

⚠ Operating without element or loose element allows dirt to enter engine.

Remove air cleaner case lid springs and unhook tabs.
Remove air cleaner cover and element.
Check element and replace if damaged.
Clean element in warm soapy water or non-flammable solvent, dry thoroughly.
Dip filter in clean engine oil, squeeze out excess oil.
Install air cleaner in reverse order of removal.

Air Cleaner Element Cleaning maintenance

⚠ Do not twist the foam filter when squeezing.

⚠ Prevent dirt from entering the air duct that leads to the carburetor.

Clean the foam air filter in warm soapy water, rinse, and allow to dry thoroughly, or clean in non-flammable solvent and dry.
Dip the foam air filter in clean engine oil, then squeeze out all excess oil.
Wipe dirt from the air cleaner housing and cover using a moist rag.

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Voltage reconnection

Voltage	Phase	Connection	Leads	Notes
120 V		Voltage selector switch in "120V ONLY" position		Only the 120V receptacles can be used; do not use the 120/240V receptacle in this position; rated power available at the 30A 120V twist lock receptacle
120/240 V		Voltage selector switch in "120/240V" position		The 120V and 120/240V receptacles can be used simultaneously; required if a 240V appliance is connected to the 4-prong receptacle

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Aftermarket parts that fit this engine

35120-Z5T-003 FridayParts $10.90 12209-ZE8-003 FridayParts $15.00 16100-ZF6-V01 FridayParts $17.95 30700-Z1C-813 KuduParts $12.00 FridayParts $14.20 19511-ZE3-000 FridayParts $26.56 16551-ZE3-000 FridayParts $16.05 FP-XP-0034625

Parts listed by aftermarket suppliers as fitting this engine — leads compiled from supplier catalogs; verify the exact part for your serial number.

Filters for this engine

Air filter: Donaldson P822686 Wix 46449

Cross-referenced via Donaldson + OEM/engine-maker interchange — options to verify against your serial number, not confirmed for every exact variant.

Also used in

Ditch Witch 1330 — Trencher

Other equipment known to use this engine, via filter-application cross-reference — useful for sourcing parts even when your exact machine isn't listed elsewhere on this page.

Common questions

What is the oil capacity of the Honda GX390T2?

The Honda GX390T2 engine has an oil capacity of 1.1 liters.

What is the displacement of the Honda GX390T2?

The Honda GX390T2 has a displacement of 0.389 liters with 1 cylinders.

Which generators use the Honda GX390T2 engine?

The Honda GX390T2 powers 4 generator set(s), including Honda EB5000, Honda EB6500, Honda EM5000SXK3, Honda EM6500SXK2.

What air filter does the Honda GX390T2 use?

The Honda GX390T2 uses air filter part numbers Donaldson P822686, Wix 46449.

How often should you change the oil in the Honda GX390T2?

The Honda GX390T2 oil change interval is every 300 hours.

What is a common problem with the Honda GX390T2 engine?

A commonly reported issue on generators using the Honda GX390T2 is: Engine will not rev sufficiently. Cause: Engine oil level low. Fix: Inspection: (page 3-3).