GX340/390

Powerful. Reliable. Durable.

With the GX340 and 390, you’re looking at some of the best engines in the business. Powerful, reliable, durable, and quiet. Honda’s GX Series is power you can trust, and then some.

Common application:

  • Pressure washers
  • Commercial lawn and garden equipment
  • Tillers / cultivators
  • Generators
  • Forestry equipment
  • Construction / industrial equipment
  • Agricultural equipment
  • Small vehicles
  • Water pumps
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Features

Fuel Efficient, High Output Operation

  • Digital CDI ignition system with variable timing Learn More
  • Increased compression ratio
  • Precision camshaft design offers precise valve timing and optimal valve overlap for better fuel efficency
  • OHV design for increased efficiency and optimal power transfer

Smooth Performance

  • Precision engineered components result in lower vibration
  • Ball bearing supported crankshaft for greater stability
  • Heavy duty balancer shaft
  • Improved piston design

Exceptionally Quiet

  • Large capacity, multi-chamber exhaust system
  • Improved camshaft and muffler reduce overall engine noise by up to 5 dB
  • Reduced mechanical noise due to piston design
  • Forged steel crankshaft and rigid crankcase
  • Helical cut gears
  • Sophisticated air intake system

Proven Reliability

  • Oil Alert Learn More
  • Cast iron cylinder sleeve
  • High quality materials, fit, and finish
  • Dual element air cleaner
  • Fuel Valve
  • 3-Year Limited Warranty

Easy to Use and Maintain

  • Simple throttle control
  • Large fuel tanks
  • Large automotive type fuel cap
  • Dual oil drains and fill
  • Easy, convenient, heavy duty control box
  • Easily accessible spark plug

Easy Starting

  • Heavy duty recoil starter
  • Automatic mechanical de-compression system Learn More
  • Variable ignition timing

Emissions Compliant

  • EPA certified
  • No catalyst necessary

Available Options

  • Low profile versions
  • Gear reduction options
  • Electric start
  • Spark arrester available
  • Charge and lamp coils with multiple output options available
  • Cyclone Air Cleaner available (Select models)

Specifications

GX340

GX390

Engine Type
Air-cooled 4-stroke OHV
Air-cooled 4-stroke OHV
Bore x Stroke
88 X 64 mm
88 X 64 mm
Displacement
389 cm3
389 cm3
Net Power Output*
10.7 hp (8.0 kW) @ 3,600 rpm
11.7 hp (8.7 kW) @ 3,600 rpm
Net Torque
19.5 lb-ft (26.4 Nm) @ 2,500 rpm
19.5 lb-ft (26.5 Nm) @ 2,500 rpm
PTO Shaft Rotation
Counterclockwise (from PTO shaft side)
Counterclockwise (from PTO shaft side)
Compression Ratio
8.2:1
8.2:1
Lamp/Charge coil options
25W, 50W / 1A, 3A, 10A, 17A
25W, 50W / 1A, 3A, 10A, 17A, 25A
Carburetor
Butterfly Float Type
Butterfly Float Type
Ignition System
Digital CDI with variable timing
Digital CDI with variable timing
Starting System
Recoil/electric
Recoil/electric
Lubrication System
Splash
Splash
Governor System
Centrifugal Mass Type
Centrifugal Mass Type
Air Cleaner
Dual element
Dual element
Oil Capacity
1.16 US qt (1.1 L)
1.16 US qt (1.1 L)
Fuel Tank Capacity
6.4 U.S. qts (6.1 liters)
6.4 U.S. qts (6.1 liters)
Fuel
Unleaded 86 octane or higher
Unleaded 86 octane or higher
Dry Weight
69 lb (31.5 kg)
69 lb (31.5 kg)
WARNING: California Prop 65 Info

DIMENSIONS

GX340

GX390

Length (min)
16.0" (407 mm)
16.0" (407 mm)
Width (min)
19.1" (485 mm)
19.1" (485 mm)
Height (min)
17.7" (449 mm)
17.7" (449 mm)

Performance Curves

The SAE J1349 standard measures net horsepower with the manufacturer’s production muffler and air cleaner in place. Net horsepower more closely correlates with the power the operator will experience when using a Honda engine powered product. The power rating of the engines indicated in this document measures the net power output at 3600 rpm(7000 rpm for model GXH50, GXV50, GX25 and GX35) and net torque at 2500 rpm, as tested on a production engine. Mass production engines may vary from this value. Actual power output for the engine installed in the final machine will vary depending on numerous factors, including the operation speed of the engine in application, environmental conditions, maintenance and other variables.

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