Honda GX620 K1

Honda GX620 K1 engineThe Honda GX620 K1 is a 614 cc (37.5 cu·in) natural aspirated V-twin four-stroke air-cooled internal combustion small gasoline engine with a horizontal shaft, manufactured by Honda Motor Company for general-purpose applications. The GX610 used to concrete saws, pressure washers, chipper and shredders, trenchers, generators, vibratory rollers, ride-on cement trowels, lawn tractors

The Honda GX620 K1 engine has a V-twin, overhead valve (OHV) design and recoil starter or electric starter. This engine used horizontal type carburetor with butterfly valve, transistorized magneto ignition system, forced type lubricating system, and forced-air cooling system. The engine is fitted with the dual element air cleaner.

The Honda GX620 K1 engine produced 20.3 PS (14.9 kW; 20.0 HP) at 3,600 rpm of maximum output power and 44.1 N·m (4.5 kg·m, 32.5 ft·lb) at 2,500 rpm of peak torque.

General information

Engine Specifications
Engine modelGX620 K1
Engine type4-stroke, OHV, V-twin
Displacement614 cm3, (37.5 cu·in)
Max. horsepower20.3 PS (14.9 kW; 20.0 HP) at 3,600 rpm
Max. torque44.1 N·m (4.5 kg·m, 32.5 ft·lb) at 2,500 rpm
Cooling systemForced air
Air cleanerDual element type
Lubricating systemForced lubrication
Ignition systemTransistorized magneto ignition
Fuel systemHorizontal type carburetor with butterfly valve
Fuel consumption313 g/kWh
Fuel usedUnleaded gasoline (octane number 86 or higher)
Starting systemRecoil or electric starter
Stoping systemIgnition primary circuit ground
GovernorCentrifugal govervor
PTO shaft rotationCounterclockwise (from PTO shaft side)
Dimensions (L x W X H)388 x 457 x 452 mm (15.3 x 18 x 17.8 in)
Dry weight42.0 kg (92.6 lbs)

Cylinder Block and Head

It has a 77.0 mm (3.03 in) cylinder bore and 66.0 mm (2.6 in) piston stroke. Compression ratio rating is 8.3:1. Each piston is fitted with two compression and single oil ring.

Cylinder block
Compression ratio:8.3:1
Cylinder bore:77.0 mm (3.03 in)
Piston stroke:66.0 mm (2.6 in)
Cylinder internal diameter (standard):77.000 mm (3.0315 in)
Piston skirt outer diameter (standard):76.985 mm (3.0309 in)
Number of piston rings (compression / oil):2/1
Connecting rod small end diameter (standard):18.005 mm (0.7089 in)
Piston pin diameter:18.000 mm (0.7087 in)
Side clearance (Top):0.030-0.060 mm (0.0012-0.0024 in)
Side clearance (Second):0.030-0.060 mm (0.0012-0.0024 in)
Ring end gap (Top):0.20-0.40 mm (0.0079-0.0157 in)
Ring end gap (Second):0.20-0.40 mm (0.0079-0.0157 in)
Ring width (Top):1.990 mm (0.0783 in)
Ring width (Second):1.990 mm (0.0783 in)
Crankshaft main journal diameter:38.000 mm (1.4961 in)
Crankpin journal diameter:39.995 mm (1.5746 in)
Crankshaft center distance:33 mm (1.3 in)
Cylinder head
Valve arrangement:OHV, gear driven
Valves::2 per cilinder (4 valves in total)
Valve steam diameter (INTAKE):6.590 mm (0.2594 in)
Valve steam diameter (EXHAUST):6.550 mm (0.2579 in)
Valve spring free length (INTAKE):39.0 mm (1.5354 in)
Valve spring free length (EXHAUST):39.0 mm (1.5354 in)
Camshaft lobe height (INTAKE):29.865 mm (1.1758 in)
Camshaft lobe height (EXHAUST):29.865 mm (1.1758 in)
Camshaft journal diameter :16.985 mm (0.6687 in)

Tightening torque

Tightening torque settings
Connecting rod bolt:12 Nm; 1.2 kg·m; 9 ft·lb
Cylinder head bolt:34 Nm; 3.5 kg·m; 25 ft·lb
Socket bolt:27 Nm; 2.7 kg·m; 20 ft·lb
Flywheel nut:196 Nm; 20.0 kg·m; 145 ft·lb
Pivot bolt:24 Nm; 2.4 kg·m; 17 ft·lb
Pivot adjusting nut:10 Nm; 1.0 kg·m; 7 ft·lb
Cylinder head cover bolt:9 Nm; 0.9 kg·m; 6.5 ft·lb
Oil drain bolt:39 Nm; 4.0 kg·m; 29 ft·lb

Service Data

The Honda 4-stroke or an equivalent (SG or SF) oil with a viscosity of SAE 10W-30 or 10W-40 is recommended for the GX620 K1, refilling oil capacity is 1.50 L (1.59 US. qt, 1.32 Imp. qt.). Recommended spark plug are NGK: ZGR5A DENSO: J16CR-U with 0.7-0.8 mm (0.0276-0.0315 in) spark plug gap.

The valve clearance is 0.13-0.17 mm (0.0051-0.0067 in) for intake valves and 0.18-0.20 mm (0.0071-0.0079 in) for exhaust valves. Standard cylinder compression is 6.0-8.0 kg/cm2 (85-121 psi) at 600 rpm.

Maximum speed:3,850±150 rpm
Idle speed:1,400 ±150 rpm rpm
Cylinder compression:6.0-8.0 kg/cm2 (85-121 psi) at 600 rpm
Valve clearance
Intake valve clearance:0.15±0.02 mm (0.006±0.001 in)
Exhaust valve clearance:0.20±0.02 mm (0.008±0.001 in)
Oil system
Lubrication system:Forced lubrication
Oil type:Honda 4-stroke or an equivalent (SG or SF)
Recommended oil:SAE 10W-30 or 10W-40
Oil capacity: Without oil filter: 1.50 L (1.59 US. qt, 1.32 Imp. qt.)
With oil filter: 1.80 L (1.90US. qt, 1.58 Imp. qt.)
Fuel system
Type:Horizontal type carburetor with butterfly valve
Main jet:#105
Float height:14.0 mm (0.5512 in)
Pilot screw opening:1-3/4 turns out
Ignition system
Type:Transistorized magneto ignition
Ignition timing:B.T.D.C. 20° (Fixed)
Spark plug:NGK: ZGR5A DENSO: J16CR-U
Spark plug gap:0.7-0.8 mm (0.0276-0.0315 in)
Spark plug torque:18 N·m (1.8 kg·m, 13.3 ft·lb)
Ignition coil air gap0.2-0.6 mm (0.0079-0.0079 in)
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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We try to use official documentation and verify the published data, but errors may occur. In addition, specifications of machinery and equipment may vary depending on markets and modifications. We do not recommend the use of this data for spare parts or repairs. Use official service manuals or parts catalogs for your product.

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