Honda iGX390

Honda iGX390The Honda iGX390 is a 0.39 l (389 cc, 23.7 cu·in) single-cylinder air-coolled 4-stroke internal combustion small gasoline (petrol) engine with horizontal shaft, manufactured by Honda Motor for general-purpose applications. The iGX390 is a modified version of the GX390 engine with STR (Self Tuning Regulator) governor, so it is suitable for applications that require features like Auto-Idle and Auto-Choke.

The iGX390 engine has variable ignition timing C.D.I.(Capacitor Discharge Ignition) type magneto ignition, horizontal type, butterfly valve carburetor, and recoil or electric starter motor. The iGX390 cylinder bore is 88.0 mm (3.5 in) and piston stroke is 64.0 mm (2.5 in), compression ratio rating is 8.2:1.

The Honda iGX390 produces 11.7 HP (8.7 kW; 11.8 PS) at 3600 rpm of net power or 9.4 HP (7.0 kW) at 3600 rpm of continuous rated power and 26.5 N·m (2.7 kgf·m, 19.5 lb·ft) at 2500 rpm of net torque.

General information

Engine Specifications
Model iGX390
Type 4-stroke, OVH, single cylinder, inclined by 25°
Displacement 289 cm 3 (23.7 cu·in)
Max. horsepower 11.7 HP (8.7 kW; 11.8 PS) at 3600 rpm
Max. torque 26.5 N·m (2.7 kgf·m, 19.5 lb·ft) at 2500 rpm
Carburetor Horizontal type, butterfly valve
Cooling system Forced-air
Ignition system Digital C.D.I.(Capacitor Discharge Ignition) with variable ignition timing
Lubricating system Forced splash
Starting system Recoil and Starter motor
Stoping system Ignition exciter coil circuit open
Fuel used Unleaded gasoline (octane number 86 or higher)
Fuel consumption 3.5 Liters (0.92 US gal, 0.77 Imp gal) / h
PTO shaft rotation Counterclockwise (from PTO shaft side)

Cylinder Block and Head

The Honda iGX390 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. The engine has integrated ECU (electronic control unit) with a self-tuning regulator (STR) governor system.

Cylinder block
Compression ratio: 8.2:1
Bore x Stroke 88 X 64 mm (3.5 x 2.5 in)
Sleeve internal diameter 88.000-88.017 mm (3.4646-3.4652 in)
Piston skirt outer diameter 87.975-87.985 mm (3.4635-3.4640 mm)
Number of piston rings (compression / oil): 2 / 1
Ring side clearance Top 0.015-0.060 (0.0006-0.0024)
Second 0.030-0.060 (0.0012-0.0024)
Ring end gap Top 0.20-0.35 mm (0.0079-0.0138 in)
Second 0.35-0.50 mm (0.0138-0.0197 in)
Oil (side rail) 0.2-0.7 mm (0.01-0.03 in)
Ring width Top 1.160-1.190 mm (0.0457-0.0470 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 6.575-6.590 mm (0.2589-0.2594 in)
EXHAUST 6.535-6.550 mm (0.2573-0.2579 in)
Cam height: INTAKE 32.498-32.698 mm (1.2794-1.2873 in)
EXHAUST 31.985-32.185 mm (1.2592-1.2671 in)
Camshaft outer diameter: 15.966-15.984 mm (0.6286-0.6293 in)

Tightening torque specs

Tightening torque specs
Connecting rod bolt (M8x1.25 Special) 14 Nm; 1.4 kg·m; 10 ft·lb
Cylinder head bolt (M10x1.25) 35 Nm; 3.5 kg·m; 25 ft·lb
Flywheel nut (M16x1.5 Special) 115 Nm; 11.5 kg·m; 83 ft·lb
Rocker arm pivot lock nut (M6x0.5) 10 Nm; 1.0 kg·m; 7 ft·lb
Rocker arm pivot bolt (M8x1.25 Special) 24 Nm; 2.4 kg·m; 17 ft·lb
Crankcase cover bolt (M8x1.25) 24 Nm; 2.4 kg·m; 17 ft·lb
Oil level switch joint nut (M10x1.25) 10 Nm; 1.0 kg·m; 7 ft·lb
Fuel filter joint nut (M10x1.25) 2 Nm; 0.2 kg·m; 1.4 ft·lb
Muffler mounting nut (M8x1.25) 24 Nm; 2.4 kg·m; 17 ft·lb
Air cleaner wing nut (M6x1.0) 9 Nm; 0.9 kg·m; 6.5 ft·lb
Oil drain bolt (M12x1.5) 23 Nm; 2.3 kg·m; 17 ft·lb
Fuel tank bolt (M8x1.25) 24 Nm; 2.4 kg·m; 17 ft·lb
Air cleaner mounting nut (M6x1.0) 10 Nm; 1.0 kg·m; 7 ft·lb
Fuel strainer cup (M24x1.0) 4 Nm; 0.4 kg·m; 2.9 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 3,600 ± 150 rpm
Idle speed 1,400 ± 150 rpm
Cylinder compression 13.2 kg/cm2 (187 psi, 1.29 MPa) at 600 rpm
Valve clearance
Intake valve 0.15 ± 0.02 (0.006 ± 0.001)
Exhaust valve 0.20 ± 0.02 (0.008 ± 0.001)
Carburetor
Main jet BE92B A: #100
Float height 13.2 mm (0.52 in)
Pilot screw opening BE92B A: 3 turns out
Oil system
Oil type Honda 4-stroke or an equivalent (SE or later)
Recommended oil SAE 10W-30
Oil capacity 1.1 L (1.16 US gal, 0.97 lmp qt)
Ignition system
Ignition timing B.T.D.C. 10° / 1,400 rpm
Spark plug NGK: BPR6ES
DENSO: W20EPR-U
Spark plug gap 0.7-0.8 mm (0.028-0.031 in)
Ignition coil air gap 0.2-0.6 mm (0.01 – 0.02 in)
Starter motor
Brush length 7.0 mm (0.28 in) limit: 3.5 mm (0.14 in)
Mica depth 1.0 mm (0.04 in) limit: 0.2 (0.01)
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3 Comments

  1. can i buy A dr pro XL 321 with the honda igx390 11.7 8.7kw engine with electronic control unit and self turning regulator governor system.

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