USED HONDA GX390 ENGINE FOR SALE

Used Honda GX390 Engine for Sale: Commercial Power and Legendary Reliability

Searching for a dependable power source for your commercial equipment, pressure washer, generator, mini bike, or go-kart project? Our selection of used Honda GX390 engines for sale offers the perfect blend of performance, durability, and value. The Honda GX390 has earned a reputation across construction sites, rental fleets, racing tracks, and homeowner garages as one of the most reliable small engines ever built. With its commercial-grade construction, proven longevity (5,000 to 10,000 plus hours in commercial service is routine), and direct compatibility with virtually any 13 HP single-cylinder application, the GX390 is the go-to choice when reliability matters.

Engine Overview: The Honda GX390

The Honda GX390 is a powerhouse in the world of small commercial engines, known for its reliability and versatility across an enormous range of applications. This 389 cc, single-cylinder, air-cooled, OHV (overhead valve) 4-stroke engine delivers 11.7 HP (8.7 kW) at 3,600 RPM with a robust design featuring a durable cast iron cylinder sleeve, ball bearing supported crankshaft, and high compression ratio of 8.2:1 (the live spec listing shows “8:2:1” which is a typo for 8.2:1). Available in both horizontal shaft and vertical shaft configurations with options for recoil start or electric start, the GX390 is purpose-built for serious commercial and industrial use.

A Note on the HP Rating: 11.7 HP vs 13 HP

You may see the Honda GX390 referenced as either an “11.7 HP” or “13 HP” engine. This is not a different engine , it’s the same GX390 with two different power ratings. In 2010, Honda revised its power rating methodology to comply with SAE J1995 gross power testing standards, which produced more conservative numbers. The same GX390 that was rated 13 HP gross before 2010 is now rated 11.7 HP gross. The engine itself, internals, and performance are identical. Older equipment manuals and labels will say “13 HP Honda,” while newer documentation says “11.7 HP.”

Why the Honda GX390 is the Gold Standard

Several engineering features make the GX390 the benchmark for commercial small engines:

• Cast Iron Cylinder Sleeve: Provides excellent wear resistance and extends engine life dramatically compared to aluminum-bore engines. Many GX390s exceed 10,000 hours of service.

• Ball Bearing Supported Crankshaft: Reduces friction and wear, smoother operation, and better tolerance of side loads from belt-driven applications.

• Honda Oil Alert System: Automatically shuts down the engine when oil level drops below safe operation, preventing the catastrophic damage that destroys lesser engines.

• Dual-Element Air Cleaner: Standard foam pre-filter plus paper element provides superior protection against dust, sand, and debris , critical for construction site and farm use.

• Automatic Mechanical Decompression: Reduces compression during starting, making pull-starting easier and reducing wear on the starter and operator.

• Quiet Muffler with Spark Arrestor: USFS-approved spark arrestor included for use in forested areas, paired with effective sound attenuation.

• Easy Maintenance: Side-by-side air cleaner and carburetor access, simple oil drain location, and Honda’s modular parts design make field service straightforward.

• Honda Parts Availability: Honda maintains parts availability for decades. Even older GX390s remain fully serviceable with new genuine Honda parts.

Versatility and Applications

The GX390 is suitable for an enormous range of applications. The most common include:

Pressure Washers:

• Commercial / contractor pressure washers from 3,000 to 4,400 PSI

• Hot water pressure washer applications

• Used in rental fleet pressure washers (Honda-powered units are the industry standard)

Generators:

• Portable generators rated 5,000 to 7,000 watts continuous output

• Honda EU series (high-end), Generac, Westinghouse, Briggs portable generators commonly use GX390

• Construction site / job site portable generators

Construction Equipment:

• Concrete mixers (both pulled-trailer and stationary units)

• Plate compactors and rammers

• Tampers

• Small cement saws

• Wood chippers

Water Pumps:

• Commercial centrifugal water pumps 3-inch to 4-inch discharge

• Trash pumps

• Diaphragm pumps

Recreational Equipment:

• Mini bikes (Coleman BT200X, Massimo MB200, Hammerhead, etc.)

• Go-karts (kid karts to adult racing karts)

• Drift trikes

• Small ATVs and offroad vehicles

Industrial / Agricultural:

• Log splitters (commercial and consumer)

• Hydraulic power packs

• Stump grinders

• Tillers and rotovators

• Air compressors (twin-tank wheelbarrow style)

Honda GX390 vs Competitor 13 HP Engines

The GX390 competes against several major commercial small engines:

The Honda GX390 vs Predator 13 HP / GX390 Clones

A common question: how does the Honda GX390 compare to the Predator 13 HP from Harbor Freight (or other Chinese clones)?

• Honda GX390: Higher initial cost (~$1,200 new), longer service life (8,000 to 10,000 plus hours common), genuine Honda parts availability for decades, lower vibration, better starting in cold weather, better quality control

• Predator 13 HP / clones: Lower initial cost (~$300-400 new), shorter service life (2,000 to 4,000 hours typical), parts availability less certain over time, more vibration, may struggle in cold weather

For commercial / professional use, the Honda’s price premium pays for itself in longevity and uptime. For occasional home use or short-life applications (e.g. one season of a yard project), a clone may make economic sense.

Compatibility , Will This GX390 Fit My Equipment?

The GX390 is designed to be interchangeable across the vast majority of equipment that originally used a GX390 or competitor 13 HP engine. Key compatibility factors:

• Shaft orientation: Horizontal shaft (most common for pressure washers, generators, mini bikes) or vertical shaft (mostly walk-behind mowers)

• Shaft type: Tapered (with keyway), threaded (3/4″ or 1″) for direct pump attachment, or splined for chain drive

• Shaft size: Standard 1-inch diameter (25.4mm) on most horizontal shafts

• Mounting bolt pattern: GX390 has a standard mounting pattern that matches most equipment frames
• Crankshaft offset: Specific to PTO requirement

Why Buy a Used Honda GX390?

A quality used GX390 offers compelling value:

• Cost savings vs new: $599 used vs $1,200+ new

• Proven service: Many used GX390s pulled from working equipment with verified hours

• Long remaining life: A GX390 with 2,000-3,000 hours has another 5,000+ hours of life in commercial service

• Genuine Honda quality: No risk of getting a clone marketed as a Honda

FAQs

Is the Honda GX390 actually 11.7 HP or 13 HP?