Kubota D640

Kubota D640The Kubota D640 is a 638 cc (38.9 cu·in) natural aspirated three-cylinders four-stroke liquid-cooled internal combustion small diesel engine, manufactured by Kubota for general-purpose applications.

The cylinder bore is 66.0 mm (2.60 in) and the piston stroke is 62.2 mm (2.45 in).

This engine produced 16.0 PS (11.8 KW; 15.8 HP) at 3,200 rpm of horsepower.

The Kubota D640 features:

  • Spherical type combustion chamber
  • Fuel injection pump
  • Centrifugal governor
  • Forced lubrication by trochoid pump
  • Water cooling system with pressurized radiator
  • Electric starter (12V, 0.7 kW)

General information

Engine Specifications
Engine model D640
Engine type 4-stroke, OHV, three-cylinders
Displacement 638 cm3, (38.9 cu·in)
Max. horsepower 16.0 PS (11.8 KW; 15.8 HP) at 3,200 rpm
Max. torque
Cooling system Liquid-cooled with pressurized radiator
Lubricating system Forced lubrication by trochoid pump
Fuel system Injection pump
Fuel used Diesel fuel No.2-D
Starting system Electric starter (12V, 0.7 kW)
Governor Centrifugal governor
PTO shaft rotation Counterclockwise (from PTO shaft side)

Cylinder Block and Head

Cylinder block
Compression ratio:
Cylinder bore: 66.0 mm (2.60 in)
Piston stroke: 62.2 mm (2.45 in)
Cylinder internal diameter (standard): 66.130-65.960 mm (2.6044-2.5984 in)
Piston skirt outer diameter (standard): 65.906 mm (2.5957 in)
Number of piston rings (compression / oil): 2/1
Ring end gap (Top): 0.430-0.885 mm (0.0169-0.0348 in)
Ring end gap (Second): 0.430-0.885 mm (0.0169-0.0348 in)
Crankshaft main journal diameter: 39.934-39.950 mm (1.5722-1.5728 in)
Crankpin journal diameter: 33.959-33.975 mm (1.337-1.3376 in)
Crankshaft center distance: 31.1 mm (1.225 in)
Cylinder head
Valve arrangement: OHV, gear driven
Valves: 4 (2 valves in total)
Valve head diameter (INTAKE): 26.00 mm (1.0236 in)
Valve head diameter (EXHAUST): 22.50 mm (0.8858 in)
Valve steam diameter (INTAKE): 5.980 mm (0.2354 in)
Valve steam diameter (EXHAUST): 5.980 mm (0.2354 in)

Service Data

Valve clearance
Intake valve clearance: 0.145-0.185 mm (0.0057-0.0073 in)
Exhaust valve clearance: 0.145-0.185 mm (0.0057-0.0073 in)
Oil system
Lubrication system: Forced lubrication by trochoid pump
Oil type: API CC or CD
Recommended oil: SAE 30, 10W-30
Oil capacity: 3.0 liters (3.17 US.qts, 2.64 Imp. qts)
Oil filter type: Full flow paper filter (cartridge)
Cooling system
Type Liquid-cooled with pressurized radiator
Coolant capacity 2.1 liters (2.22 US.qts, 1.85 Imp. qts)
Fuel system
Type: Injection pump
Electrical system
Battery: 12V, 35AH or equivalent
Starting motor Electric starter (12V, 0.7 kW)
ATTENTION! Dear visitors, this is an informational database of technical specifications, we are not a parts supplier or a marketplace.

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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