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Home / Industrial Engines / Kubota Engines / Kubota D850

Kubota D850 Specifications

Engine Model: Kubota D850

Engine Type: 4-cycle 3-cylinder liquid-cooled diesel engine

Total Displacement: 52.2 cu.in (0.85 L)

Rated Engine Power: 19.8 Hp (14.9 kW) at 3200 rpm

Aspiration Type: Naturally aspirated

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General Technical Data

Engine Model .............. Kubota D850
Engine Type .............. Vertical, water-cooled, 4-cycle diesel
Number of cylinders .............. 3
Bore, mm (in) .............. 72.0 (2.83)
Stroke, mm (in) .............. 70.0 (2.76)
Total displacement, cm3 (cu. in) .............. 855 (52.2)
Gross power, kw (hp) .............. 14.9 (19.8)
Net power, kw (hp) .............. 13.4 (18.0)
Maximum speed, rpm .............. 3200
Idling speed, rpm .............. 800
Maximum torque, Nm (ft-lb) .............. 50.6 (37.3)
Torque speed, rpm .............. 1800
Combustion Chamber .............. Spherical type
Direction of rotation .............. Counter-clockwise
Compression ratio .............. 22:1
Firing order .............. 1-2-3

Fuel System

Fuel injection pump .............. Bosch K type mini pump
Injection nozzle .............. Bosch Throttle type
Injection timing, deg (rad) .............. 25 (0.44) before T.D.C.
Injection pressure, MPa (psi) .............. 13.7 (1990)
Governor .............. Centrifugal ball mechanical governor
Injection timing, deg (rad) .............. 23-25 (0.402-0.436) before T.D.C.
Fuel tightness of pump element, MPa (psi) .............. 14.7 (2133)
Fuel tightness of delivery valve, MPa (psi) .............. 14.7-13.7 (2133-1990)
Fuel injection pressure .............. 13.73-14.71 (1991-2133)

Lubricating System

Lubricating system .............. Forced lubrication by pump
Oil pressure indicating .............. Electrical type switch
Oil filter .............. Full flow paper filter (cartridge type)
Engine oil pressure at idle speed, kPa (psi) .............. 68 (10)
Engine oil pressure at rated speed, kPa (psi) .............. 196-441 (29-64)
Inner rotor to outer rotor clearance, mm (in) .............. 0.11-0.15 (0.0043-0.0059)
Outer rotor to pump body clearance, mm (in) .............. 0,07-0.15 (0.0028-0.0059)
Inner rotor to cover end clearance, mm (in) .............. 0.08-0.13 (0.0031-0.0051)

Electrical System

Starting system .............. Electric starting with starter
Starting Motor .............. 12V, 0.8 kW
Starting support device .............. By glow plug in combustion chamber
Battery .............. 12V, 65 AH
Dinamo for Charging .............. 12V, 150W

Dimensions and Weight

Overall Length, mm (in) .............. 475 (18.8)
Overall Width, mm (in) .............. 423 (16.7)
Overall Height, mm (in) .............. 566 (22.3)
Dry weight, kg (lbs.) .............. 82.6 (182.1)

Cylinder Block

Cylinder liner I.D, mm (in) .............. 72.000-72.019 (2.8347-2.8354)
Oversized cylinder liner I.D, mm (in) .............. + 0.5 (0.0197)
Clearance between tappet and guide, mm (in) .............. 0.020-0.062 (0.0008-0.0024)
Tappet O.D, mm (in) .............. 19.959-19.980 (0.7858-0.7866)
Tappet guide I.D, mm (in) .............. 20.000-20.021 (0.7874-0.7882)
Crankshaft alignment, mm (in) .............. 0.02 (0.0008)
Crankshaft bearing 1 oil clearance, mm (in) .............. 0.034-0.106 (0.0013-0.0042)
Crankshaft O.D, mm (in) .............. 43.934-43.950 (1.7297-1.7303)
Crankshaft bearing 1 I.D, mm (in) .............. 43.984-44.040 (1.7317-1.7339)
Crankshaft bearing 2 oil clearance, mm (in) .............. 0.034-0.092 (0.0013-0.0036)
Crankshaft bearing 2 I.D, mm (in) .............. 43.984-44.026 (1.7317-1.7333)
Crank pin bearing oil clearance, mm (in) .............. 0.029-0.087 (0.0011-0.0034)
Crank pin O.D, mm (in) .............. 36.959-36.975 (1.4551-1.4557)
Crank pin bearing I.D, mm (in) .............. 37.004-37.046 (1.4569-1.4585)
Crankshaft side clearance, mm (in) .............. 0.15-0.31 (0.0059-0.0122)
Crankshaft sleeve wear, mm (in) .............. 0.1 (0.0039)
Connecting rod alignment, mm (in) .............. 0.05 (0.0020)
Piston pin to small end bushing clearance, mm (in) .............. 0.014-0.038 (0.0006-0.0015)
Piston pin O.D, mm (in) .............. 20.002-20.011 (0.7875-0.7878)
Small end bushing I.D, mm (in) .............. 20.025-20.040 (0.7884-0.7890)

Cylinder Head and Valves

Cylinder head surface flatness, mm (in) .............. 0.05 (0.0019)
Top clearance, mm (in) .............. 0.6-0.8 (0.0237-0.0315)
Cylinder head gasket shim thickness, mm (in) .............. 0.2 (0.0079)
Cylinder head gasket thickness (Free), mm (in) .............. 1.15-1.30 (0.0453-0.0512)
Cylinder head gasket thickness (Tightened), mm (in) .............. 1.05-1.15 (0.0413-0.0453)
Compression pressure, MPa (psi) .............. 3.09-2.32 (448-337)
Valve clearance (Cold), mm (in) .............. 0.145-0.185 (0.0057-0.0072)
Intake/exhaust valve seat width, mm (in) .............. 2.12 (0.0835)
Intake/exhaust valve seat angle, deg (rad) .............. 45 (0.785)
Intake/exhaust valve-face angle, deg (rad) .............. 45.5 (0.794)
Valve recessing, mm (in) .............. 0.9-1.1 (0.036-0.043)
Valve stem to valve guide clearance, mm (in) .............. 0.035-0.065 (0.0014-0.0025)
Valve stem O.D, mm (in) .............. 6.960-6.975 (0.2741-0.2746)
Valve guide I.D, mm (in) .............. 7.010-7.025 (0.2760-0.2765)
Intake valve (Open), deg (rad) .............. 20 (0.35) before T.D.C
Intake valve (Close), deg (rad) .............. 45 (0.79) after B.D.C
Exhaust valve (Open), deg (rad) .............. 50 (0.87) before T.D.C
Exhaust valve (Close), deg (rad) .............. 15 (0.26) after B.D.C
Valve spring free length, mm (in) .............. 35.1-35.6 (1.382-1.401)
Valve spring tilt, mm (in) .............. 1.3 (0.051)
Rocker arm shaft O.D, mm (in) .............. 10.973-10.984 (0.4320-0.4324)
Rocker arm bearing I.D, mm (in) .............. 11.000-11.041 (0.4331-0.4347)
Camshaft side clearance, mm (in) .............. 0.07-0.22 (0,0028-0.0087)
Camshaft alignment, mm (in) .............. 0.01 (0.0004)
Cam height (Intake/Exhaust), mm (in) .............. 26.88-26.83 (1.0583-1.0563)
Oil clearance of camshaft, mm (in) .............. 0.050-0.091 (0.0020-0.0036)
Camshaft journal O.D, mm (in) .............. 32.934-32.950 (1.2966-1.2972)
Camshaft bearing I.D, mm (in) .............. 33.000-33.025 (1.2992-13002)

Timing Gear

Timing gear backlash, mm (in) .............. 0.042-0.115 (0.0017-0.0045)
Idle gear side clearance, mm (in) .............. 0.20-0,51 (0.0079-0.0201)
Idle gear shaft to gear bushing clearance, mm (in) .............. 0.016-0.045 (0.0006-0.0018)
Idle gear shaft O.D, mm (in) .............. 17.973-17.984 (0.7076-0.7080)
Idle gear bushing I.D, mm (in) .............. 18.000-18.018 (0.7087-0.7054)

Piston and Piston Rings

Piston pin bore, mm (in) .............. 20.000-20.013 (0.7874-0.7879)
Compression ring groove clearance, mm (in) .............. 0.085-0.112 (0.0033-0.0044)
Compression ring groove width, mm (in) .............. 1.555-1.570 (0.0613-0.0618)
Compression ring width, mm (in) .............. 1.458-1.470 (0.0574-0.0579)
Oil ring groove clearance, mm (in) .............. 0.020-0.055 (0.0008-0.0021)
Oil ring groove width, mm (in) .............. 4.010-4.030 (0.1579-0.1587)
Oil ring width, mm (in) .............. 3.975-3.990 (0.1565-0.1571)
Ring end gap (Compression ring 1), mm (in) .............. 0.25-0.40 (0.0098-0.0157)
Ring end gap (Compression ring 2), mm (in) .............. 0.25-0.40 (0.0098-0.0157)
Ring end gap (Oil ring), mm (in) .............. 0.25-0.40 (0.0098-0.0157)

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