The Kohler ZT720 is a 725 cc (44.2 cu·in) natural aspirated V-twin four-stroke air-cooled internal combustion small gasoline engine from the Confidant series with a vertical shaft, manufactured by Kohler Co for general-purpose applications.
A 83.0 mm (3.27 in) cylinder bore and 67.0 mm (2.64 in) piston stroke give the ZT720 engine a total of 725 cc of displacement. The compression ratio rating is 9.1:1.
The ZT720 engine produced 21.4 PS (15.7 KW; 21.0 HP) at 3,600 rpm of maximum horsepower and 55.2 Nm (5.63 kg·m; 40.74 ft·lb) at 2,200 rpm of maximum torque.
The Kohler ZT720 features:
- High-impact nylon shroud and valve cover
- OHV design
- Aluminum cylinder block
- Cast iron cylinder liners
- Electronic ignition system
- Carburetor with fixed main jet (Walbro or Keihin)
- Mechanical centrifugal governor
- Full pressure lubrication system
- Forced air cooling system
- Electric or recoil starter
General information
Engine Specifications | |
Engine model | Confidant ZT720 |
Engine type | 4-stroke, OHV, V-twin |
Displacement | 725 cm3, (44.24 cu·in) |
Max. horsepower | 21.4 PS (15.7 KW; 21.0 HP) at 3,600 rpm |
Max. torque | 55.2 Nm (5.63 kg·m; 40.74 ft·lb) at 2,200 rpm |
Cooling system | Forced air |
Air cleaner | Heavy-duty air cleaner |
Lubricating system | Full pressure |
Ignition system | Electronic ignition system |
Fuel system | Carburetor with fixed main jet (Walbro or Keihin) |
Fuel used | Unleaded gasoline (octane number 86 or higher) |
Starting system | Electric or recoil starter |
Governor | Mechanical centrifugal governor |
PTO shaft rotation | Counterclockwise (from PTO shaft side) |
Dimensions (L x W X H) | 478 x 443 x 431 mm (18.8 × 17.5 × 17.0 in) |
Dry weight | 41.3 kg (91.0 lbs) |
Cylinder Block and Head
Cylinder block | |
Compression ratio: | 9.1:1 |
Cylinder bore: | 83.0 mm (3.27 in) |
Piston stroke: | 67.0 mm (2.64 in) |
Cylinder internal diameter (standard): | 82.988-83.013 mm (3.2672-3.2682 in) |
Thrust face outer diameter (standard): | 82.978 mm (3.2668 in) |
Piston pin diameter: | 16.995-17.000 mm (0.6691-0.6693 in) |
Number of piston rings (compression / oil): | 2/1 |
Side clearance (Top): | 0.030-0.070 mm (0.0010-0.0026 in) |
Side clearance (Second): | 0.030-0.070 mm (0.0010-0.0026 in) |
Side clearance (Oil): | 0.060-0.190 mm (0.0022-0.0073 in) |
Ring end gap (Top): | 0.189-0.277 mm (0.0074-0.0109 in) |
Ring end gap (Second): | 1.519-1.797 mm (0.0598-0.0708 in) |
Number of main bearings: | 2 |
Crankshaft main journal diameter: | 40.913-40.935 mm (1.6107-1.6116 in) |
Crankpin journal diameter: | 35.950-35.974 mm (1.4154-1.4163 in) |
Cylinder head | |
Valve arrangement: | OHV, gear driven |
Valves: | 2 (4 valves in total) |
Valve head diameter (INTAKE): | 33.370-33.630 mm (1.3138-1.324 in) |
Valve head diameter (EXHAUST): | 29.370-29.630 mm (1.1563-1.1665 in) |
Valve seat angle (INTAKE): | 89° |
Valve seat angle (EXHAUST): | 89° |
Valve seat angle (INTAKE): | 45° |
Valve seat angle (EXHAUST): | 45° |
Valve steam diameter (INTAKE): | 6.982-7.000 mm (0.2749-0.2756 in) |
Valve steam diameter (EXHAUST): | 6.970-6.988 mm (0.2744-0.2751 in) |
Valve lift minimal (INTAKE): | 8.500 mm (0.3346 in.) |
Valve lift minimal (EXHAUST): | 8.500 mm (0.3346 in.) |
Camshaft journal diameter: | 19.948-19.960 mm (0.7854-0.7858 in) |
Tightening torque specs
Tightening torque specs | |
Intake manifold mounting (torque in 2 increments) | Step 1: 7.4 Nm (0.75 kg·m; 5.5 ft·lb) Step 2: 9.9 Nm (1.00 kg·m; 7.3 ft·lb) |
Cylinder head bolt (torque in 2 increments) | Step 1: 22.6 Nm (2.31 kg·m; 16.7 ft·lb) Step 2: 41.8 Nm (4.26 kg·m; 30.8 ft·lb) |
Rocker arm stud | 11.3 Nm (1.2 kgf·m; 8.3 ft·lb) |
Rocker arm adjuster setscrew | 7.9 Nm (0.8 kgf·m; 5.8 ft·lb) |
Connecting rod cap | Black Coating: 11.3 Nm (1.2 kgf·m; 8.3 ft·lb) Gray Metallic Coating: 13.6 Nm (1.4 kgf·m; 10.0 ft·lb) |
Flywheel retaining screw | 74.5 Nm (7.6 kgf·m; 55.0 ft·lb) |
Governor lever nut | 6.8 Nm (0.7 kgf·m; 5.0 ft·lb) |
Oil drain plug | 13.6 Nm (1.4 kgf·m; 10.0 ft·lb) |
Spark plug | 27.0 Nm (2.75 kg·m; 20.0 ft·lb) |
Service Data
Engine | |
Maximum speed: | 3600±50 rpm |
Idle speed: | 1200±75 rpm |
Compression pressure | |
Standard: | 1.1 MPa (160 psi) |
Compression differential limit between cylinders: | 15% and less |
Oil system | |
Lubrication system: | Full pressure |
Oil type: | API SG, SH, SJ, or higher |
Recommended oil: | SAE 10W-30 |
Oil capacity: | W/o oil filter: 1.7 L (1.8 US. qt, 1.5 Imp. qt.) With oil filter: 1.9 L (2.0 US.qts, 1.7 Imp. qts) |
Fuel system | |
Type: | Carburetor with fixed main jet (Walbro or Keihin) |
Fuel pump: | Pulse type |
Fuel filter: | In-line |
Ignition system | |
Type: | Electronic ignition system |
Spark plug: | Champion RC12YC |
Spark plug gap: | 0.76 mm (0.030 in) |
Ignition coil air gap | 0.203-0.305 mm (0.008-0.012 in) |
References
1. Kohler Confidant ZT710-ZT740 service manual. Kohler Co. 2021.
We try to use official documentation and verify the published data, but errors may occur. In addition, specifications of machinery and equipment may vary depending on markets and modifications. We do not recommend the use of this data for spare parts or repairs. Use official service manuals or parts catalogs for your product.
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