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Kubota WG1605 Engine

General Technical Data

Kubota WG1605 Engine Specifications

Engine Model .............. Kubota WG1605
Engine Type .............. Vertical water-cooled 4-cylinder gasoline/LPG
Number of Cylinders .............. 4
Total Displacement, L (cu.in) .............. 1.54 (93.8)
Cylinder Bore, mm (in) ................ 79.0 (3.11)
Piston Stroke, mm (in) ................ 78.4 (3.09)
Rated Engine Power (Gas), hp (kW) ................ 51.6 (38.5)
Rated Engine Power (LPG), hp (kW) ................ 49.8 (37.1)
Rated Engine Speed, rpm ................ 3600
Maximum Speed, rpm ................ 3575-3625
Idle Speed, rpm ................ 725-775
Maximum Torque (Gas), Nm (lb-ft) ................ 120 (89)
Maximum Torque (LPG), Nm (lb-ft) ................ 113 (84)
Torque Speed (Gas), rpm ................ 2400
Torque Speed (LPG), rpm ................ 2500
Compression Ratio ................ 9.1:1
Firing Order ................ 1-3-4-2
Direction of Rotation ................ Counter-clockwise (viewed from flywheel)
Lubrication System ................ Forced lubrication by trochoid pump
Cooling System ................ Forced circulation with water pump
Ignition System ................ Full transistor battery type
Starting System ................ Electric starter
Electrical System Rating, Volts ................ 12

Fuel System

Fuel System Type ................ Carburetor/Vaporizer
Carburetor Type ................ Fixed main jet
Governor Type ................ Electronic
Fuel Type ................ Gasoline (86 or higher) or Standard Commercial LP Gas

Dimensions and Weight

Overall Length, mm (in) ................ 592 (23.3)
Overall Width, mm (in) ................ 479 (18.9)
Overall Height, mm (in) ................ 692 (27.3)
Net Weight, kg (lbs) ................ 121 (267)

Kubota WG1605 Maintenance Data

Service Data

Cylinder Bore Inside Diameter (Max), mm (in) ................ 79.15 (3.116)
Cylinder Head (Max Out of Flatness), mm (in) ................ 0.05 (0.002)
Intake Valve Clearance, mm (in) ................ 0.145-0.185 (0.00571-00728)
Exhaust Valve Clearance, mm (in) ................ 0.145-0.185 (0.00571-00728)

Engine Oil and Filters

Engine Oil Type (Summer) ................ SAE 30, 10W-30, 15W-40
Engine Oil Type (Winter) ................ SAE 10W-30
API Service Classifications ................ SH or higher
Oil Capacity, L (qts) ................ 6.0 (6.3)
Oil Filter Part Number ................ HH160-32093
Fuel Filter Part Number ................ 13351-43010
Air Filter Part Number ................ 17351-11083

Ignition System

Spark Plug Type ................ NGK IFR6F8DN
Spark Plug Gap, mm (in) ................ 0.7-0.8 (0.028-0.031)
Ignition Timing (Gas), deg ................ 26 BTDC
Ignition Timing (LPG), deg ................ 20 BTDC
Spark Plug Torque, Nm (ft-lbs) ................ 25-30 (18-21.6)

Service Intervals

Check and Adjust Spark Plug ................ Every 100 hours
Clean Air Filter Element ................ Every 100 hours
Clean Fuel Filter ................ Every 100 hours
Change Engine Oil ................ Every 200 hours
Replace Engine Oil Filter ................ Every 200 hours
Check Fan Belt Tension ................ Every 500 hours
Check PCV Valve ................ Every 1000 hours
Check coolant Hose of LPG Vaporizer ................ Every 1000 hours
Check LPG Lock Off Valve ................ Every 1000 hours
Replace Spark Plug ................ Every 1000 hours
Replace Air Filter Element ................ Every 1000 hours
Replace Fuel Filter ................ Every 1000 hours
Check and Adjust Valve Clearance ................ Every 1000 hours

Kubota WG1605 Service Specifications

Cylinder Block

Cylinder Bore I.D (Std), mm (in) ................ 79.000-79.019 (3.1103-3.1109)
Crankshaft Alignment, mm (in) ................ 0.02 (0.00079)
Crankshaft Side Clearance (Std), mm (in) ................ 0.15-0.31 (0.0059-0.012)
Crankshaft Side Clearance (Wear Limit), mm (in) ................ 0.50 (0.0197)
Crankshaft Journal to Bearing 1 Oil Clearance, mm (in) ................ 0.0340-0.114 (0.00134-0.00448)
Crankshaft Journal to Bearing 2 Oil Clearance, mm (in) ................ 0.034-0.095 (0.0014-0.0037)
Crankshaft Journal O.D, mm (in) ................ 47.934-47.950 (1.8872-1.8877)
Crankshaft Bearing 1 I.D, mm (in) ................ 47.984-48.048 (1.8892-1.8916)
Crankshaft Bearing 2 I.D, mm (in) ................ 47.984-48.029 (1.8892-1.8909)
Crankpin to Crankpin Bearing Oil Clearance, mm (in) ................ 0.065-0.091 (0.0026-0.0035)
Crankpin O.D, mm (in) ................ 39.959-39.975 (1.5732-1.5738)
Crankpin Bearing I.D, mm (in) ................ 40.040-40.050 (1.5764-1.5767)

Cylinder Head and Valves

Cylinder Head Surface Flatness, mm (in) ................ 0.05 (0.002)
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)
Valve Seat Width, mm (in) ................ 2.12 (0.0835)
Valve Face Angle (Intake), deg ................ 60
Valve Face Angle (Exhaust), deg ................ 60
Valve Spring Free Length, mm (in) ................ 35.1-35.6 (1.39-1.40)
Camshaft Side Clearance, mm (in) ................ 0.0700-0.220 (0.00276-0.00866)
Camshaft Alignment, mm (in) ................ 0.01 (0.0004)
Camshaft Journal to Cylinder Bore Clearance, mm (in) ................ 0.050-0.091 (0.00197-0.00358)
Camshaft Journal O.D, mm (in) ................ 35.934-35.950 (1.4148-1.4153)
Cam Height (Intake), mm (in) ................ 28.80 (1.134)
Cam Height (Exhaust), mm (in) ................ 29.00 (1.142)

Piston and Piston Rings

Piston Pin Bore I.D (Std), mm (in) ................ 22.000-22.013 (0.86615-0.86665)
Piston Pin Bore I.D (Wear Limit), mm (in) ................ 22.03 (0.8673)
Piston Pin O.D, mm (in) ................ 22.002-22.011 (0.86622-0.86657)
Piston Pin to Small End Bushing Clearance, mm (in) ................ 0.014-0.038 (0.00056-0.0014)
Piston Pin Small End Bushing I.D, mm (in) ................ 22.025-22.040 (0.86713-0.86771)
Top Ring Groove Clearance, mm (in) ................ 0.040-0.080 (0.0016-0.0031)
Second Ring Groove Clearance, mm (in) ................ 0.030-0.070 (0.0012-0.0027)
Oil Ring Groove Clearance, mm (in) ................ 0.020-0.19 (0.00079-0.0074)
Top Ring End Gap, mm (in) ................ 0.30-0.45 (0.0118-0.0177)
Second Ring End Gap, mm (in) ................ 0.30-0.45 (0.0118-0.0177)
Oil Ring End Gap, mm (in) ................ 0.20-0.70 (0.0079-0.027)

Kubota WG1605 Tightening Torque Specs

Cylinder head screw (M10x1.25), Nm (lb-ft) ................ 63.7-68.6 (47-50.5)
Cylinder head cover cap nut (M7x1.0), Nm (lb-ft) ................ 6.9-8.8 (5.1-6.5)
Rocker arm bracket nut (M7x1.0), Nm (lb-ft) ................ 21.6-26.5 (16-19.5)
Fan drive pulley screw (M14x1.5), Nm (lb-ft) ................ 235-245 (174-180)
Connecting rod screw (M8x1.0), Nm (lb-ft) ................ 41.2-46.1 (30.4-34)
Flywheel screw (M10x1.25), Nm (lb-ft) ................ 53.9-58.8 (39.8-43.3)
Bearing case cover screw (M6x1.0), Nm (lb-ft) ................ 9.8-11.3 (7.2-8.3)
Main bearing case screw 1 (M8x1.25), Nm (lb-ft) ................ 29.4-34.3 (21.7-25.2)
Main bearing case screw 2 (M9x1.25), Nm (lb-ft) ................ 49-53.9 (36.2-39.7)
Idle gear shaft mounting screw (M6x1.0), Nm (lb-ft) ................ 9.8-11.3 (7.2-8.3)
Injection pump gear cap nut (M12x1.5), Nm (lb-ft) ................ 58.8-68.6 (43.4-50.5)
Drain plug (M12x1.25), Nm (lb-ft) ................ 32.4-37.3 (23.9-27.5)
Rotation sensor mounting screw (M6x1.0), Nm (lb-ft) ................ 3-6 (2.3-4.4)
Spark plug (M14x1.25), Nm (lb-ft) ................ 24.5-29.4 (18.1-21.6)
Ignition coil mounting screw (M6x1.0), Nm (lb-ft) ................ 9.8-11.3 (7.2-8.3)
Knock sensor mounting screw (M6x1.0), Nm (lb-ft) ................ 15-25 (11.1-18.4)
Water temperature sensor (M12x1.5), Nm (lb-ft) ................ 16.7-19.6 (12.4-14.4)
PCV Valve (M16x1.5), Nm (lb-ft) ................ 16-24 (11.8-17.7)
Exhaust manifold mounting nut (M7x1.0), Nm (lb-ft) ................ 15.7-18.6 (11.6-13.7)
Alternator’s pulley nut, Nm (lb-ft) ................ 58.3-78.9 (43-58.2)

KUBOTA TRACTORS TROUBLESHOOTING
L235	L2501	L2550	L275	L3110
L3301	L35	L3710	L3901	L4310
L5030	M4700	M5700	M6040	M6800
M8200	M8540	M9000	MX5100	MX5200