The Honda GXV390 is a 0.39 l (389 cc, 23.7 cu-in) air-cooled single-cylinder four-stroke internal combustion small gasoline (petrol) engine with vertical shaft manufactured by Honda Motor Company for general-purpose applications, such as commercial lawn and garden equipment, tractors, construction and industrial equipment, agricultural equipment, small vehicles.
The GXV390 engine has an OHV design with two valves; sophisticated air intake system; large capacity, multi-chamber exhaust system. The engine is equipped with a centrifugal mechanical governor, horizontal type carburetor with butterfly valve, transistorized magneto ignition system and recoil or electric starter.
The cylinder bore is 88.0 mm (3.46 in) and the piston stroke is 64.0 mm (2.5 in). Compression ratio rating is 7.7:1. The Honda GXV390 produces 13.0 HP (9.7 kW) at 3,600 rpm and 28.0 Nm (2.8 kg·m, 20.3 ft·lb) of torque at 2,500 rpm.
General information
| Engine Specifications | |
| Model | GXV390 |
| Type | 4-stroke, OHV, single cylinder |
| Displacement | 389 cm 3 (23.7 cu-in) |
| Max. horsepower | 13.0 HP (9.7 kW) at 3600 rpm |
| Max. torque (crank PTO) | 28.0 Nm (2.8 kg·m, 20.3 ft·lb) at 2,500 rpm |
| Carburetor | Horizontal type, butterfly valve |
| Cooling system | Forced-air |
| Ignition system | Transistorized magneto ignition |
| Lubricating system | Pressure and splash |
| Starting system | Recoil or electric starter |
| Stoping system | Ignition primary circuit ground |
| Fuel used | Unleaded gasoline (octane number 86 or higher) |
| Fuel tank capacity | 2.3 L (0.61 US gal, 0.51 lmp gal) |
| Fuel consumption | 313 g/kWh (230 g/HPh, 0.51 lb/HPh) |
| PTO shaft rotation | Counterclockwise (from PTO shaft side) |
Dimensions and Weight
| GXV390 | |
| Length, mm (in) | 430 (16.9) |
| Width, mm (in) | 385 (15.2) |
| Height, mm (in) | 410 (16.1) |
| Dry weight, kg (lb) | 33 (72.8) |
| Operating weight, kg (lb) |
34.5 (76.1) |
Cylinder Block and Head
The Honda GXV390 has cast iron cylinder sleeve, ball bearing supported crankshaft, improved piston design, heavy duty balancer shaft. The piston has two compression rings and one oil ring. Precision camshaft design offers precise valve timing and optimal valve overlap for better fuel efficiency.
| Cylinder block | ||
| Compression ratio: | 7.7:1 | |
| Bore x Stroke | 88 X 64 mm (3.46 x 2.5 in) | |
| Sleeve internal diameter | 88.000 mm (3.4646 in) | |
| Piston skirt outer diameter | 87.985 mm (3.4640 mm) | |
| Number of piston rings (compression / oil): | 2 / 1 | |
| Ring side clearance | Top/second | 0.030-0.060 (0.0012-0.0024) |
| Ring end gap | Top | 0.20-0.40 mm (0.0079-0.0160 in) | Second | 0.20-0.40 mm (0.0079-0.0160 in) |
| Ring width | Top | 1.160-1.175 mm (0.0457-0.0463 in) |
| Second | 1.160-1.175 mm (0.045-0.0463 in) | |
| Piston pin outer diameter | 19.994-20.000 mm (0.7872-0.7874 in) | |
| Connecting rod small end inner diameter | 20.005-20.020 mm (0.7876-0.7882 in) | |
| Connecting rod big end inner diameter | 36.025-36.039 mm (1.4183-1.4189 in) | |
| Crankpin outer diameter | 35.975-35.985 mm (1.4163-1.4167 in) | |
| Cylinder Head | ||
| Warpage (limit) | 0.10 mm (0.004 in) | |
| Valve Arrangement: | OHV | |
| Valves: | 2 | |
| Stem outer diameter (standard): | INTAKE | 6.590 mm (0.2594 in) |
| EXHAUST | 6.550 mm (0.2579 in) | |
| Cam height: | INTAKE | 32.60 mm (1.283 in) |
| EXHAUST | 32.09 mm (1.263 in) | |
| Camshaft outer diameter: | 16.000 mm (0.6299 in) | |
Tightening torque specs
| Tightening torque specs | |
| Connecting rod bolt | 14 Nm; 1.4 kg·m; 10 ft·lb |
| Cylinder head bolt | 35 Nm; 3.5 kg·m; 25 ft·lb |
| Flywheel nut | 115 Nm; 11.5 kg·m; 83 ft·lb |
| Pivot adjusting nut | 10 Nm; 1.0 kg·m; 7 ft·lb |
| Push rod guide pivot bolt | 24 Nm; 2.4 kg·m; 17 ft·lb |
| Oil pan bolt | 24 Nm; 2.4 kg·m; 17 ft·lb |
| Air cleaner body cap nut | 9 Nm; 0.9 kg·m; 6.5 ft·lb |
| Muffler mounting nut | 24 Nm; 2.4 kg·m; 17 ft·lb |
| Exhaust pipe mounting nut | 24 Nm; 2.4 kg·m; 17 ft·lb |
| Oil drain plug | 45 Nm; 4.5 kg·m; 34 ft·lb |
| Cylinder head cover bolt | 9 Nm; 0.9 kg·m; 6.5 ft·lb |
| Fuel tank bolt | 24 Nm; 2.4 kg·m; 17 ft·lb |
| Standard torque values | |
| Bolt, nut (5 mm) | 5.5 Nm; 0.55 kg·m; 4.0 ft·lb |
| Bolt, nut (6 mm) | 10 Nm; 1.0 kg·m; 7 ft·lb |
| Bolt, nut (8 mm) | 24 Nm; 2.4 kg·m; 17 ft·lb |
| Bolt, nut (10 mm) | 37.5 Nm; 3.75 kg·m; 27 ft·lb |
| Bolt, nut (12 mm) | 55 Nm; 5.5 kg·m; 40 ft·lb |
Maintenance data
| Engine | |
| Maximum speed | 3400 ± 150 rpm |
| Idle speed | 1400 ± 150 rpm |
| Cylinder compression | 5.0-8.5 kg/cm2 (71-151 psi) at 600 rpm |
| Valve clearance | |
| Intake valve | 0.10 ± 0.02 (0.004 ± 0.001) |
| Exhaust valve | 0.15 ± 0.02 (0.006 ± 0.001) |
| Carburetor | |
| Main jet | #95 |
| Float height | 11.9-14.5 mm (0.47-0.57 in) |
| Pilot screw opening | 2-1/2 turns out |
| Oil system | |
| Oil type | Honda 4-stroke or an equivalent (SE or SF) |
| Recommended oil | SAE 10W-40 |
| Oil capacity | 1.1 L (1.2 US gal, 1.0 lmp qt) |
| Ignition system | |
| Ignition timing | 20 ° B.T.D.C (Fixed) |
| Spark plug | NGK: BPR5ES NIPPONDENSO: W16EPR-U |
| Spark plug gap | 0.7-0.8 mm (0.028-0.031 in) |
| Primary ignition coil resistance | 0.7-0.9 Ω |
| Secondary ignition coil resistance | 6.3-7.7 kΩ |
| Ignition coil air gap | 0.4 ± 0.2 (0.016 ± 0.008) |
| Starter motor | |
| Brush length | 7.2 mm (0.28 in) limit: 3.5 mm (0.14 in) |
| Mica depth | 1.0 mm (0.04 in) limit: 0.2 mm (0.01 in) |
Author:
Not seeing output shaft diameter, keyway, threads??
Hi Dwayne! Have you found what’s the bolt size? Keyway is 5mm.
i need the a forward reverse reducer gearbox for this model GXV390, how can I get one?
This engine uses throttle cable to adjust speed and to stop engine. I need a throttle lever and not throttle cable to adjust speed of the engine like on GX390, GX270 and so on.
What size and thread pitch are the mounting bolts??
hai.. how i want buy this engine honda gxv390.. how much this engine?
hi where on my 390 model do i locate the model/serial numbers .
engine specs states this engine (gxv390) hp rating is 13.0, but the ferris fw15 mowers which use this engine state it is rated at 10.2 hp. which is correct ?
13HP was the former rating and 10.2HP is the current rating