Honda iGX340

Honda iGX340The Honda iGX340 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, such as pressure washers, generators, forestry equipment, construction and industrial equipment, agricultural equipment, water pumps.

The iGX340 is a modified version of the GX340 engine with STR (Self Tuning Regulator) governor, so it is suitable for applications that require features like Auto-Idle and Auto-Choke.

The iGX340 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 iGX340 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 iGX340 produces 10.7 HP (8.0 kW; 10.8 PS) at 3600 rpm of net power and 26.4 N·m (2.6 kgf·m, 19.4 lb·ft) at 2500 rpm of net torque.

General information

Engine Specifications
Type4-stroke, OVH, single cylinder, inclined by 25°
Displacement289 cm 3 (23.7 cu·in)
Max. horsepower10.7 HP (8.0 kW ; 10.8 PS) at 3600 rpm
Max. torque26.4 N·m (2.6 kgf·m, 19.4 lb·ft) at 2500 rpm
CarburetorHorizontal type, butterfly valve
Cooling systemForced-air
Ignition systemDigital C.D.I.(Capacitor Discharge Ignition) with variable ignition timing
Lubricating systemForced splash
Starting systemRecoil and Starter motor
Stoping systemIgnition exciter coil circuit open
Fuel usedUnleaded gasoline (octane number 86 or higher)
Fuel consumption3.5 Liters (0.92 US gal, 0.77 Imp gal) / h
PTO shaft rotationCounterclockwise (from PTO shaft side)

Cylinder Block and Head

The Honda iGX340 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 Stroke88 X 64 mm (3.5 x 2.5 in)
Sleeve internal diameter88.000-88.017 mm (3.4646-3.4652 in)
Piston skirt outer diameter87.975-87.985 mm (3.4635-3.4640 mm)
Number of piston rings (compression / oil):2 / 1
Ring side clearanceTop0.015-0.060 (0.0006-0.0024)
Second0.030-0.060 (0.0012-0.0024)
Ring end gapTop0.20-0.35 mm (0.0079-0.0138 in)
Second0.35-0.50 mm (0.0138-0.0197 in)
Oil (side rail)0.2-0.7 mm (0.01-0.03 in)
Ring widthTop1.160-1.190 mm (0.0457-0.0470 in)
Second1.160-1.175 mm (0.045-0.0463 in)
Piston pin outer diameter19.994-20.000 mm (0.7872-0.7874 in)
Connecting rod small end inner diameter20.005-20.020 mm (0.7876-0.7882 in)
Connecting rod big end inner diameter36.025-36.039 mm (1.4183-1.4189 in)
Crankpin outer diameter35.975-35.985 mm (1.4163-1.4167 in)
Cylinder Head
Warpage (limit)0.10 mm (0.004 in)
Valve Arrangement:OHV
Stem outer diameter (standard):INTAKE6.575-6.590 mm (0.2589-0.2594 in)
EXHAUST6.535-6.550 mm (0.2573-0.2579 in)
Cam height:INTAKE32.498-32.698 mm (1.2794-1.2873 in)
EXHAUST31.985-32.185 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

Maximum speed3,600 ± 150 rpm
Idle speed1,400 ± 150 rpm
Cylinder compression13.2 kg/cm2 (187 psi, 1.29 MPa) at 600 rpm
Valve clearance
Intake valve0.15 ± 0.02 (0.006 ± 0.001)
Exhaust valve0.20 ± 0.02 (0.008 ± 0.001)
Oil system
Oil typeHonda 4-stroke or an equivalent (SE or later)
Recommended oilSAE 10W-30
Oil capacity1.1 L (1.16 US gal, 0.97 lmp qt)
Ignition system
Ignition timingB.T.D.C. 10° / 1,400 rpm
Spark plugNGK: BPR6ES
Spark plug gap0.7-0.8 mm (0.028-0.031 in)
Ignition coil air gap0.2-0.6 mm (0.01 – 0.02 in)
Starter motor
Brush length7.0 mm (0.28 in) limit: 3.5 mm (0.14 in)
Mica depth1.0 mm (0.04 in) limit: 0.2 (0.01)
Author: Sergei Wers
About: Co-founder and CEO of a multi-brand auto repair shop (engine repair, chassis repair, body repair and painting) for over 15 years. I have been developing internet sites with technical specifications for more than seven years.

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