The Kubota D1403 is a 1.4 L (1,393 cc, 85.0 cu·in) straight-three, water-cooled naturally aspirated vertical diesel engine manufactured by Kubota. 
The Kubota D1403 engine has a spherical type сombustion сhamber, the Bosch mini fuel injection pump, and the Bosch throttle-type injection nozzle. The cylinder bore and the piston stroke are 80.0 mm (3.15) in and 92.4 mm (3.64 in), respectively. The compression ratio rating is 23.0:1.
The D1403-B(E) diesel engine produced 31.4 PS (23.1 KW; 31.0 HP) at 2,800 rpm of gross horsepower.
The breakdown of the engine code is as follows:
- D – 3-cylinders
 - 14 – Approximate displacement 1400 cc
 
General information
| Engine Specifications | |
| Engine code | D1403-B(E) | 
| Layout | Straight-3, vertical diesel engine | 
| Fuel type | Diesel fuel No.2-D | 
| Production | – | 
| Displacement | 1.4 L, 1,393 cm3 (85.0 cu in) | 
| Fuel injection pump | Bosch mini fuel injection pump | 
| Fuel nozzle | Bosch throttle-type | 
| Starting system | Electric starting with 12V (1.2 kW) starter | 
| Starting support device | Glow plug | 
| Governor | Centrifugal ball mechanical governor | 
| Power adder | None | 
| Max. Horsepower | 
Net (intermittent): 29.4 PS (21.6 KW; 29.0 HP) at 2,800 rpm Gross (intermittent): 31.4 PS (23.1 KW; 31.0 HP) at 2,800 rpm  | 
| Torque output | – | 
| Firing order | 1-2-3 | 
| Dimensions (L x W x H): | 568 x 512 x 639 mm (22.4 x 20.2 x 25.2 in) | 
| Weight | 148.0 kg (326.0 lbs) | 
Cylinder block
| Cylinder block | ||
| Compression ratio: | 23.0:1 | |
| Cylinder bore: | 80.0 mm (3.15 in) | |
| Piston stroke: | 92.4 mm (3.64 in) | |
| Number of piston rings (compression / oil): | 2 / 1 | |
| Cylinder inner diameter: | 80.000-85.019 mm (3.1496-3.1504 in) | |
| Piston skirt diameter | – | |
| Piston ring side clearance: | Second | 0.093-0.120 mm (0.0037-0.0047 in) | 
| Oil | 0.020-0.052 mm (0.0008-0.0020 in) | |
| Piston ring end gap: | Top | 0.300-0.450 mm (0.0118-0.0177 in) | 
| Second | 0.300-0.450 mm (0.0118-0.0177 in) | |
| Oil | 0.250-0.450 mm (0.0099-0.0177 in) | |
| Piston pin outer diameter | 23.002-23.011 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: | 6 (2 valves per cylinder) | |
| Valve timing: | INTAKE | – | 
| EXHAUST | – | |
| Valve seat width: | INTAKE | 2.120 mm (0.0835 in) | 
| EXHAUST | 2.120 mm (0.0835 in) | |
| Valve stem diameter: | INTAKE | 7.960-7.975 mm (0.3134-0.3140 in) | 
| EXHAUST | 7.960-7.975 mm (0.3134-0.3140 in) | |
| Valve spring free length: | INTAKE | 41.7-42.2 mm (1.6417-1.6614 in) | 
| EXHAUST | 41.7-42.2 mm (1.6417-1.6614 in) | |
| Camshaft cam height: | INTAKE | 33.470 mm (1.3177 in) | 
| EXHAUST | 33.470 mm (1.3177 in) | |
| Camshaft journal diameter: | 39.934-39.950 mm (1.5722-1.5728 in) | |
Tightening torque
| Tightening torque specs | |
| Rocker arm bracket nuts: | 22.5-27.5 Nm (2.4-2.8 kgf-m, 17.4-20.3 lb-ft) | 
| Cylinder head: | 93.1-98.0 Nm (9.5-10.0 kgf-m, 68.7-72.3 lb-ft) | 
| Nozzle holder assembly: | 49.0-68.6 Nm (5.0-7.0 kgf-m, 36.2-50.6 lb-ft) | 
| Connecting rod bolts: | 
Non-flange bolt: 36.3-41.2 Nm (3.7-4.2 kgf-m, 26.6-30.4 lb-ft) Flange bolt1: 44.1-49.0 Nm (4.5-5.0 kgf-m, 32.5-36.2 lb-ft)  | 
| Flywheel bolts: | 98.1-107.9 Nm (10.0-11.0 kgf-m, 72.3-79.6 lb-ft) | 
| Main bearing case bolts 1: | 46.1-50.9 Nm (4.7-5.2 kgf-m, 34.0-37.6 lb-ft) | 
| Main bearing case bolts 2: | 68.6-73.5 Nm (7.0-7.5 kgf-m, 50.6-54.2 lb-ft) | 
Maintenance data
| Valve clearance | |
| Intake valve | 0.18-0.22 mm (0.0071-0.0087 in) | 
| Exhaust valve | 0.18-0.22 mm (0.0071-0.0087 in) | 
| Compression pressure | |
| Standard | 36.0-38.0 kgf/cm2 (3.53-3.72 MPa, 512-540 psi) | 
| Oil system | |
| Recommended engine oil | CD or CE | 
| SAE Viscosity Number | SAE 10W-30, 10W-40 | 
| Engine oil capacity | 
Oil pan depth 90.0 mm (3.54 in): 5.6 L (1.5 US gal, 1.2 Imp. gal) Oil pan depth 124.0 mm (4.88 in): 7.0 L (1.8 US gal, 1.5 Imp. gal)  | 
| Fuel system | |
| Injection timing: | 17-19° B.T.D.C. | 
| Fuel injection pressure | 13.73 MPa (140 kgf/cm2, 1991 psi) | 
| Cooling system | |
| Thermostat’s valve opening temperature: | 69.5-72.5°C (157.1-162.5°F) | 
| Temperature at which thermostat completely opens: | 85°C (185°F) | 
| Electrical system | |
| Battery: | 12V, 70 or 80 Ah | 
| Alternator current output: | 35A/14V at 4,000 rpm | 
| Alternator brush Length (std/min): | 10.5 mm (0.4130 in) / 4.5 mm (0.1770 in) | 
| Glow plug resistance: | Approx 0.8 Ω | 
output shaft size front spline shaft on D1403 ?