Kohler KS590

Kohler KS590The Kohler KS590 is a 541 cc, (33.0 cu·in) single-cylinder air-cooled four-stroke internal combustion gasoline engine from the 5400 series, manufactured by Kohler Co.

The Kohler KS590 engine has an OHV (overhead valve) design, vertical PTO-shaft, and pressurized lubrication system. This engine is equipped with a one-barrel carburetor and an electronic ignition system.

The cylinder bore is 94.0 mm (3.70 in) and the piston stroke is 78.0 mm (3.10 in). The compression ratio rating is 8.8:1.

The KS590 engine produced 19.3 PS (14.2 KW; 19.0 HP) at 3,600 rpm of horsepower and 41.4 Nm (4.22 kg·m; 30.55 ft·lb) at 2,600 rpm of torque.

The breakdown of the engine code is as follows:

  • KS – 5400 Series
  • 590 – Numerical designation

General information

Engine Specifications
Type4-stroke, OHV, single-cylinder
Displacement541 cm 3 (33.0 cu-in)
Max. horsepower19.3 PS (14.2 KW; 19.0 HP) at 3,600 rpm
Max. torque41.4 Nm (4.22 kg·m; 30.55 ft·lb) at 2,600 rpm
Fuel systemOne-barrel carburetor
Cooling systemForced-air
Ignition systemElectronic ignition system
Lubricating systemPressurized lubrication
Starting systemElectric starter
Fuel usedUnleaded gasoline (octane number 86 or higher)
Dimensions (L x W x H)457 x 394 x 360 mm (18 x 15.5 x 14.2 in)
Dry weight34.0 kg (75.0 lbs)

Cylinder Block and Head

Cylinder block
Compression ratio:8.8:1
Bore x Stroke94.0 X 78.0 mm (3.70 x 3.10 in)
Sleeve internal diameter94.010-94.035 mm (3.7012-3.7022 in)
Piston skirt outer diameter (standard)93.975-93.989 mm (3.6998-3.7003 in)
Number of piston rings (compression / oil):2 / 1
Piston pin outer diameter21.995-22.000 mm (0.8659-0.8661 in)
Ring-to-groove side clearance:Top0.025-0.065 mm (0.0010-0.0026 in)
Second0.040-0.080 mm (0.0016-0.0032 in)
Oil0.090-0.210 mm (0.0035-0.0083 in)
Ring end gap:Top0.150-0.400 mm (0.0059-0.0157 in)
Second1.000-1.250 mm (0.0394-0.0492 in)
Main bearing journal outer diameterFlywheel End40.913-40.935 mm (1.6107-1.6116 in)
PTO End40.913-40.935 mm (1.6107-1.6116 in)
Connecting rod journal outer diameter40.982-41.000 mm (1.6135-1.6142 in)
Cylinder Head
Valve Arrangement:OHV
Valves:2 (2 per cylinder)
Valve head diameter:INTAKE35.875-36.125 mm (1.412-1.422 in)
EXHAUST32.875-33.125 mm (1.294-1.304 in)
Stem outer diameter:INTAKE5.982-6.000 mm (0.2355-0.2362 in)
EXHAUST5.970-5.988 mm (0.235-0.2357 in)
Valve lift (min):INTAKE9.4 mm (0.370 in)
EXHAUST9.3 mm (0.366 in)

Tightening torque specs

Tightening torque specs
Cylinder head (torque in 2 increments) Step 1: 24.4 Nm (2.5 kgf·m; 18.0 ft·lb)
Step 2: 42.7 Nm (4.4 kgf·m; 31.5 ft·lb)
Connecting rod (torque in 2 increments) Step 1: 5.5 Nm (0.6 kgf·m; 4.1 ft·lb)
Step 2: 11.8 Nm (1.2 kgf·m; 8.7 ft·lb)
Flywheel115.0 (11.7 kgf·m; 84.9 ft·lb)
Spark plug27 Nm (2.75 kg·m; 20.0 ft·lb)

Service Information

Valve clearance
Intake valve clearance0.101-0.152 mm (0.004-.006 in)
Exhaust valve clearance0.101-0.152 mm (0.004-.006 in)
Oil system
Oil typeAPI SJ or higher
Recommended oilSAE 10W-30
Oil capacity1.4 liters (1.5 US.qts, 1.23 Imp. qts)
Ignition system
Spark plugChampion RC12YC
Spark plug gap0.76 mm (0.030 in)
Module air gap0.203-0.305 mm (0.008-0.012 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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