Kubota Z751

Kubota Z751The Kubota Z751 is a 0.75 L (743 cc, 45.34 cu·in) straight-two, water-cooled naturally aspirated vertical diesel engine manufactured by Kubota for general-purpose applications.

A 76.0 mm (2.99 in) cylinder bore and 82.0 mm (3.23 in) piston stroke give the Kubota Z751 engine a total of 743 cc of displacement. The compression ratio rating is 21.0:1.

The Z751 diesel engine produced 17.3 PS (12.7 kW; 17.0 HP) at 2,800 rpm of output power.

The breakdown of the engine code is as follows:

  • Z – 2-cylinders
  • 751 – Approximate displacement 750 cc

General information

Engine Specifications
Engine codeZ751A
LayoutStraight-2, vertical diesel engine
Fuel typeDiesel fuel No.2-D
Displacement0.75 L, 743 cm3 (45.34 cu in)
Max. Horsepower17.3 PS (12.7 kW; 17.0 HP) at 2,800 rpm
Torque output
Injection typeIndirect injection
Cooling systemLiquid-cooled
Fuel systemFuel injection pump
Fuel nozzle
Starting systemElectric starting with 12V starter
Starting support device
GovernorCentrifugal ball mechanical governor
Power adderNone
Firing order1-2
Dimensions (L x W x H):

Cylinder block

Cylinder block
Compression ratio:21.0:1
Cylinder bore:76.0 mm (2.99 in)
Piston stroke:82.0 mm (3.23 in)
Number of piston rings (compression / oil):2 / 1
Cylinder inner diameter:76.000-76.020 mm (2.992-2.993 inches)
Piston skirt diameter
Piston ring side clearance:Second0.090-0.120 mm (0.004-0.005 in)
Oil0.020-0.050 mm (0.0008-0.0020 in)
Piston ring end gap:Top0.300-0.450 mm (0.0118-0.0177 in)
Second0.300-0.450 mm (0.0118-0.0177 in)
Oil0.250-0.400 mm (0.0098-0.0157 in)
Piston pin outer diameter23.002-23.011 mm (0.9056-0.9059 in)
Crankshaft main journal diameter:51.921-51.940 mm (2.0441-2.0449 in)
Crankpin diameter:43.959-43.975 mm (1.7307-1.7313 in)

Cylinder head

Cylinder head
Valve Arrangement:OHV, gear drive
Valves:4 (2 valves per cylinder)
Valve timing:INTAKE
Valve seat width:INTAKE2.100 mm (0.080 inch)
EXHAUST2.100 mm (0.080 inch)
Valve stem diameter:INTAKE7.960-7.975 mm (0.3134-0.3140 in)
EXHAUST7.960-7.975 mm (0.3134-0.3140 in)
Valve spring free length:INTAKE42.0 mm (1.6535 in)
EXHAUST42.0 mm (1.6535 in)
Cam height:INTAKE33.36 mm (1.3134 in)
EXHAUST33.36 mm (1.3134 in)
Camshaft journal diameter:39.935-39.950 mm (1.5722-1.5728 in)

Tightening torque

Tightening torque specs
Cylinder head screw:75.0-78.0 Nm (7.65-7.80 kgf·m, 55.3-58.0 lb·ft)
Connecting rod screw:37.0-41.0 Nm (3.8-4.2 kgf·m; 27.3-30.3 lb·ft)
Flywheel screw:54.0-58.0 Nm (5.5-5.9 kgf·m; 39.9-42.8 lb·ft)
Idle gear shaft screws:32.4-37.3 Nm (3.3-3.8 kgf·m; 23.9-27.5 lb·ft)
Bearing case cap screws:30.0-34.0 Nm (3.0-3.4 kgf·m; 22.0-25.0 lb·ft)

Maintenance data

Valve clearance
Intake valve0.18-0.22 mm (0.007-0.009 in)
Exhaust valve0.18-0.22 mm (0.007-0.009 in)
Oil system
Recommended engine oilDS or DM
SAE viscosity numberSAE 80
Engine oil capacity3.8 liters (4.02 US.qts, 3.34 Imp. qts)
Fuel system
Injection timing:25° B.T.D.C.
Fuel injection pressure13.73-14.71 MPa (140-150 kgf/cm2, 1991-2133 psi)
Cooling system
Coolant capacity:5.3 liters (5.6 US.qts, 4.7 Imp. qts)
Electrical system
Battery:12V, 65Ah or equivalent
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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