The Honda GX120 UT2/T2 is a 118 cc (7.2 cu·in) natural aspirated single-cylinder four-stroke air-cooled internal combustion small gasoline engine with horizontal shaft, manufactured by Honda Motor Company for general-purpose applications.
The GX120 UT2/T2 engine produced 3.5 PS (2.6 kW; 3.5 HP) at 3,600 rpm of maximum horsepower and 7.3 N·m (0.7 kg·m, 5.4 ft·lb) at 2,500 rpm of maximum torque.
General information
| Engine Specifications | |
| Engine model | GX120 UT2/T2 |
| Engine type | 4-stroke, OHV, single-cylinder |
| Displacement | 118 cm3, (7.2 cu·in) |
| Max. horsepower | 3.5 PS (2.6 kW; 3.5 HP) at 3,600 rpm |
| Max. torque | 7.3 N·m (0.7 kg·m, 5.4 ft·lb) at 2,500 rpm |
| Cooling system | Forced air |
| Lubricating system | Forced splash |
| Ignition system | C.D.I. (Capacitor Discharge Ignition) type magneto ignition |
| Fuel system | Horizontal type carburetor with butterfly valve |
| Fuel consumption | 1.0 L (0.26 US gal, 0.22 Imp gal) / h |
| Fuel tank capacity | 2.0 L (0.53 US. gal. 0.44 Imp. gal.) |
| Fuel used | Unleaded gasoline (octane number 86 or higher) |
| Starting system | Recoil starter |
| Stoping system | Ignition primary circuit ground |
| PTO shaft rotation | Counterclockwise (from PTO shaft side) |
| Dimensions (L x W X H) | Type H: 370 x 346 x 329 mm (14.6 x 13.6 x 13 in) |
| Dry weight | 15.5 kg (34.2 lbs) |
Cylinder Block and Head
| Cylinder block | |
| Compression ratio: | 8.5:1 |
| Cylinder bore: | 60.0 mm (2.36 in) |
| Piston stroke: | 42.0 mm (1.65 in) |
| Cylinder internal diameter (standard): | 60.000-60.015 mm (2.3622-2.3628 in) |
| Piston skirt outer diameter (standard): | 59.965-59.985 mm (2.3608-2.3616 in) |
| Number of piston rings (compression / oil): | 2 / 1 |
| Connecting rod big end diameter (standard): | 26.020-26.033 mm (1.0244-1.0249 in) |
| Connecting rod small end diameter (standard): | 13.005 -13.020 mm (0.512-0.5126 in) |
| Piston pin diameter: | 12.994-13.000 mm (0.5116-0.5118 in) |
| First ring side clearance: | 0.035-0.070 mm (0.0014-0.0028 in) |
| Second ring side clearance: | 0.045-0.080 mm (0.0018-0.0031 in) |
| First ring end gap: | 0.200-0.350 mm (0.0079-0.0138 in) |
| Second ring end gap: | 0.350-0.500 mm (0.0138-0.0197 in) |
| Oil ring end gap: | 0.200-0.700 mm (0.0079-0.0276 in) |
| First ring width: | 0.950-0.970 mm (0.0374-0.0382 in) |
| Second ring width: | 0.940-0.960 mm (0.037-0.0378 in) |
| Crankpin journal diameter: | 25.970-25.980 mm (1.0224-1.0228 in) |
| Crankshaft center distance: | 21 mm (0.825 in) |
| Cylinder head | |
| Valve arrangement: | OHV, gear driven |
| Valves:: | 2 |
| Intake valve steam diametr: | 5.468-5.480 mm (0.2153-0.2157 in) |
| Exhaust valve steam diametr: | 5.425 -5.440 mm (0.2136-0.2142 in) |
| Intake valve spring free length: | 30.5 mm (1.2008 in) |
| Exhaust valve spring free length: | 30.5 mm (1.2008 in) |
| Intake camshaft lobe height: | 27.500-27.900 mm (1.0827-1.0984 in) |
| Exhaust camshaft lobe height: | 27.547-27.947 mm (1.0845-1.1003 in) |
| Camshaft journal diameter : | 13.966 -13.984 mm (0.5498-0.5506 in) |
Tightening torque
| Tightening torque specs | |
| Connecting rod bolt | 12 Nm; 1.2 kg·m; 9 ft·lb |
| Cylinder head bolt | 24 Nm; 2.4 kg·m; 17 ft·lb |
| Flywheel nut | 75 Nm; 7.5 kg·m; 54 ft·lb |
| Rocker arm pivot adjusting nut | 10 Nm; 1.0 kg·m; 7 ft·lb |
| Rocker arm pivot bolt | 24 Nm; 2.4 kg·m; 17 ft·lb |
| Crankcase cover bolt | 12 Nm; 1.2 kg·m; 9 ft·lb |
| Oil level switch joint nut | 10 Nm; 1.0 kg·m; 7 ft·lb |
Service Data
| Engine | |
| Maximum speed: | 3,800-4,000 rpm |
| Idle speed: | 1,250-1,600 rpm |
| Cylinder compression: | 0.49-0.69 MPa (5.0-7.0 kgf/cm2 , 71-100 psi) / 600 rpm |
| Valve clearance | |
| Intake valve clearance: | 0.13-0.17 mm (0.0051-0.0067 in) |
| Exhaust valve clearance: | 0.18-0.22 mm (0.0071-0.0087 in) |
| Oil system | |
| Lubrication system: | Forced splash |
| Oil type: | SAE 10W-30 |
| Recommended oil: | Honda 4-stroke or an equivalent (SE or SF) |
| Oil capacity: | 0.56 L (0.59 US. qt, 0.49 Imp. qt.) |
| Fuel system | |
| Type: | Horizontal type carburetor with butterfly valve |
| Main jet: |
BE60W A: #62 BE99A A: #60 BE61M A: #62 BE99B A: #62 |
| Float height: | 13.7 mm (0.54 in) |
| Pilot screw opening: |
BE60W A: 2-1/8 turns out BE99A A: 1-5/8 turns out BE61M A: 2-1/8 turns out BE99B A: 2-1/8 turns out |
| Ignition system | |
| Type: | C.D.I. (Capacitor Discharge Ignition) type magneto ignition |
| Ignition timing: | B.T.D.C. 20° / 1,400 rpm |
| Spark plug: | NGK: BPR6ES DENSO: W20EPR-U |
| Spark plug gap: | 0.7-0.8 mm (0.0276-0.0314 in) |
| Spark plug torque: | 18 N·m (1.8 kg·m, 13.3 ft·lb) |
| Ignition coil air gap | 0.2-0.6 mm (0.0079-0.0240 in) |
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