Description
Honda GX390 PA2 Engine Overview
The Honda GX390 PA2 Horizontal Engine is a powerful and dependable replacement engine designed for compatible equipment that requires a horizontal crankshaft gasoline engine. It is part of Honda’s well-known GX engine family, a series widely used in commercial, industrial, agricultural, and outdoor power equipment applications.
This model is listed as Honda GX390-PA2 and GX390UT2PA2. It has a 389cc displacement and produces 11.7 net HP, giving it the strength needed for demanding equipment where consistent power and durability matter.
The engine uses a recoil starter, making it a pull-start unit rather than an electric-start engine. It also features a horizontal crankshaft orientation, which must match the equipment’s original engine layout.
The Honda GX390 PA2 includes a threaded crankshaft configuration, dual ball bearing support, cast iron cylinder bore, dual-element air cleaner, float carburetor, manual choke, and Digital CDI ignition with variable timing.
For equipment owners and repair shops, this engine is a strong replacement option when the original engine has failed, lost compression, become difficult to start, or can no longer provide reliable output under load.
Equipment Fitment and Common Applications
The Honda GX390 PA2 horizontal engine is designed for compatible equipment requiring a horizontal shaft engine with matching crankshaft size, PTO rotation, mounting pattern, and shaft type.
This engine uses a 1-1/4-inch x 3-1/2-inch threaded crankshaft. The description also references a 1-14 UNF SAE threaded x 3-31/64-inch crankshaft, so buyers should carefully compare the crankshaft details with the original engine and equipment requirement before ordering.
The crankshaft rotates counterclockwise from the PTO side, which is another important fitment detail. Rotation direction affects compatibility with pumps, generators, pressure washers, compressors, construction equipment, and other driven components.
This engine is commonly selected for compatible commercial and industrial equipment where Honda GX-series power is required. It may be used in equipment categories such as pressure washers, generators, water pumps, air compressors, small construction machinery, agricultural equipment, and other machines that accept the correct GX390 PA2 configuration.
Before purchase, buyers should confirm crankshaft orientation, shaft diameter, shaft length, threaded shaft requirement, PTO height, bolt circle, rotation direction, air cleaner clearance, exhaust routing, throttle control, choke control, and mounting base compatibility.
389cc Honda GX Power and Durability
The Honda GX390 PA2 is built around a 389cc single-cylinder gasoline engine platform. With 11.7 net HP, it provides strong output for equipment that needs reliable power under frequent use.
The engine uses a cast iron cylinder bore, which supports durability and long service life when properly maintained. Cast iron bore construction is especially important in commercial-use engines because it helps resist wear in demanding operating environments.
The dual ball bearing design provides additional support for the crankshaft. This is useful in equipment applications where the engine may operate under steady load or frequent duty cycles.
The dual-element air cleaner helps protect the engine from dirt, dust, and debris. This is important for jobsite, outdoor, and agricultural environments where airborne contaminants can shorten engine life if filtration is poor.
For buyers who need a serious replacement engine rather than a light-duty option, the Honda GX390 PA2 horizontal engine offers a dependable power platform with practical commercial-grade features.
Starting, Ignition, and Fuel System Details
The Honda GX390-PA2 uses a recoil starter, meaning it starts with a pull-start system. This keeps the engine simple and avoids the added wiring and battery requirements of an electric-start configuration.
The ignition system is Digital CDI with variable timing, which supports reliable spark control and smoother engine operation when properly maintained.
The engine uses a float carburetor and runs on gasoline. A manual choke control is included, giving the operator direct control during cold starting.
This model does not include a fuel pump, so buyers should confirm that their equipment’s fuel tank position and fuel delivery setup are compatible with the engine configuration.
It also does not include an oil cooler. Proper oil level, correct oil type, clean cooling airflow, and routine maintenance are important for long-term performance.
The engine includes low oil shutdown, helping protect the engine by shutting it down when oil level becomes unsafe. It does not include a separate low oil alert.
Crankshaft, PTO, and Mounting Details
The crankshaft is one of the most important fitment points on the Honda GX390 PA2 Horizontal Engine. This model uses a threaded crankshaft listed as 1-1/4 inch x 3-1/2 inch, with additional description noting 1-14 UNF SAE threaded x 3-31/64 inch.
Because crankshaft dimensions and thread type directly affect equipment compatibility, buyers should compare the original engine shaft carefully before ordering. Even small differences in shaft length, diameter, thread type, or PTO setup can prevent proper installation.
The crankshaft keyway width is listed as none, and the crankshaft end tapped size is listed as N/A. These details matter for equipment that connects directly to a pump, coupler, pulley, clutch, generator head, or other driven component.
The crankshaft rotation direction is counterclockwise from the PTO side. The listed PTO height is 5-1/4 inches, and the bolt circle is listed as 5, 6-1/2.
Correct PTO height and bolt circle matching help support proper alignment between the engine and the driven equipment.
Key Benefits for Equipment Owners and Repair Shops
The Honda GX390 PA2 Horizontal Engine gives buyers a dependable replacement option with strong specifications and trusted Honda engineering.
The 389cc displacement and 11.7 net HP output make it suitable for demanding equipment that needs consistent power. The horizontal crankshaft orientation and threaded shaft design provide clear fitment details for compatible machinery.
The cast iron cylinder bore supports durability, while dual ball bearings provide crankshaft support for demanding use. The dual-element air cleaner helps protect the engine in dusty working environments.
The low oil shutdown feature adds engine protection, and the Digital CDI ignition with variable timing supports reliable ignition performance.
For repair shops, this engine offers a clear replacement option for customers who need a Honda GX390-style horizontal shaft engine with the correct crankshaft and mounting configuration.
Who This Engine Is Best For
This engine is best for equipment owners, repair shops, maintenance teams, contractors, agricultural users, and professional installers who need a compatible Honda GX390 PA2 replacement engine.
It is suitable for equipment requiring a 389cc horizontal shaft gasoline engine with a recoil starter, threaded crankshaft, counterclockwise PTO rotation, and the listed shaft dimensions.
This product is a strong choice when the original engine has failed because of low compression, hard starting, internal wear, oil-related damage, ignition problems, or age-related performance decline.
It is also appropriate for buyers who need a durable engine with cast iron cylinder bore, dual ball bearings, dual-element air cleaner, and low oil shutdown.
This engine is not intended for equipment requiring an electric starter, vertical shaft layout, gear reduction, fuel pump, different crankshaft size, different rotation direction, or different PTO height unless compatibility has been confirmed.
Technical Details and Included Features
The Honda GX390 PA2 Horizontal Engine is a 389cc gasoline horizontal shaft engine rated at 11.7 net HP. It uses a recoil starter, threaded crankshaft, float carburetor, and Digital CDI ignition with variable timing.
This engine is listed with a 1-1/4-inch x 3-1/2-inch crankshaft, counterclockwise PTO rotation, dual ball bearings, cast iron cylinder bore, and low oil shutdown.
| Specification | Details |
|---|---|
| Product Type | Horizontal shaft replacement engine |
| Brand | Honda |
| Model Number | GX390-PA2 |
| Alternate Model Reference | GX390UT2PA2 |
| Engine Family | Honda GX Series |
| Net Horsepower | 11.7 HP |
| Displacement | 389cc |
| Fuel System | Gasoline |
| Starter Type | Recoil |
| Crankshaft Orientation | Horizontal |
| Crankshaft Type | Threaded |
| Crankshaft Dimensions | 1-1/4 in. x 3-1/2 in. |
| Additional Shaft Reference | 1-14 UNF SAE threaded x 3-31/64 in. |
| Crankshaft Length | 3-1/2 in. |
| Crankshaft End Tapped Size | N/A |
| Crankshaft Keyway Width | None |
| PTO Rotation Direction | Counterclockwise from PTO side |
| PTO Height | 5-1/4 in. |
| Gear Reduction | No |
| Bearing Type | Dual ball |
| Cylinders | 1 |
| Cylinder Bore Type | Cast iron |
| Air Cleaner Type | Dual element |
| Fuel Pump | No |
| Oil Cooler | No |
| Oil Capacity | 38 |
| Low Oil Alert | No |
| Low Oil Shutdown | Yes |
| Ignition System | Digital CDI with variable timing |
| Carburetor Type | Float |
| Choke Control | Manual |
| Bolt Circle | 5, 6-1/2 |
| Shipping Weight | 30 |
| Warranty | 3-year consumer and commercial warranty |
Fitment Support and Ordering Notes
Before ordering the Honda GX390 PA2 Horizontal Engine, buyers should confirm that it matches the original engine and equipment setup. Important details include engine model, crankshaft orientation, shaft diameter, shaft length, threaded shaft configuration, PTO rotation, PTO height, bolt circle, mounting base, recoil starter setup, fuel system requirements, choke control, and available installation space.
This engine is listed with no gear reduction, no fuel pump, and no oil cooler. Buyers should confirm that these omitted features are not required for their equipment.
The engine includes low oil shutdown, but it does not include a separate low oil alert. It uses a manual choke and a recoil starter, so it should be selected only for compatible applications.
Customers can also compare this product with other Honda GX engines, compatible horizontal shaft engines, pressure washer engines, generator engines, pump engines, air filters, spark plugs, recoil starter parts, engine oil, couplers, pulleys, and mounting hardware when planning a complete equipment repair.
Frequently Asked Questions
What equipment is the Honda GX390 PA2 engine used for?
The Honda GX390 PA2 Horizontal Engine is used in compatible equipment requiring a 389cc horizontal shaft gasoline engine with the correct threaded crankshaft, PTO rotation, mounting pattern, and shaft dimensions. Buyers should verify fitment before ordering.
How much horsepower does the Honda GX390 PA2 produce?
The Honda GX390 PA2 is rated at 11.7 net HP with 389cc displacement. It is designed for demanding equipment applications that require dependable horizontal shaft power.
What are the crankshaft dimensions?
This engine is listed with a 1-1/4-inch x 3-1/2-inch threaded crankshaft. The description also references 1-14 UNF SAE threaded x 3-31/64-inch, so buyers should compare the original engine carefully before purchase.
Does this Honda GX390 engine have electric start?
No. The Honda GX390 PA2 uses a recoil starter, meaning it is a pull-start engine. It is not listed as an electric-start model.
Does this engine have low oil shutdown?
Yes. This model includes low oil shutdown, which helps protect the engine by shutting it down when oil level becomes unsafe. It does not include a separate low oil alert.
What direction does the crankshaft rotate?
The crankshaft rotation direction is listed as counterclockwise from the PTO side. Buyers should verify this against the equipment’s driven component before ordering.
What warranty comes with this engine?
The Honda GX390 PA2 Horizontal Engine includes a 3-year consumer and commercial warranty. Buyers should review the warranty terms for coverage details, maintenance requirements, and installation conditions.
