Kohler PCH680

Kohler PCH680The Kohler PCH680 is a 747 cc (45.6 cu·in) natural aspirated V-twin four-stroke air-cooled internal combustion small propane engine from the Command PRO EFI Propane series with a horizontal shaft, manufactured by Kohler Co for general-purpose applications.

A 83.0 mm (3.27 in) cylinder bore and 69.0 mm (2.72 in) piston stroke give the PCH680 engine a total of 747 cc of displacement. The compression ratio rating is 9.1:1.

The PCH680 engine produces 23.4 PS (17.2 KW; 23.0 HP) at 3,600 rpm of maximum horsepower and 49.8 Nm (5.1 kg·m; 36.7 ft·lb) at 2,200 rpm of peak torque.

The Kohler PCH680 features:

  • High efficiency overhead valve design
  • Hydraulic valve lifters
  • Aluminum cylinder block
  • Cast iron cylinder liners
  • Hardened, micro-polished, dynamic-balanced crankshaft
  • PTO side-load sleeve bearing
  • 12V high energy electronic ignition system
  • Closed-loop electronic fuel injection (EFI) for propane fuel
  • Engine-mounted electronic control unit (ECU)
  • Engine-mounted propane fuel pressure regulator for Vapor Withdrawal
  • Variable speed governor
  • Engine-mounted keyswitch and throttle controls
  • Full pressure lubrication system
  • Forced air cooling system
  • High efficiency, low-noise cooling fan
  • High torque solenoid shift starter
  • 20 Amp regulated charging system

General information

Engine Specifications
Engine modelCommand PRO EFI Propane PCH680
Engine type4-stroke, OHV, V-twin
Displacement747 cm3, (45.6 cu·in)
Max. horsepower23.4 PS (17.2 KW; 23.0 HP) at 3,600 rpm
Max. torque49.8 Nm (5.1 kg·m; 36.7 ft·lb) at 2,200 rpm
Cooling systemForced air
Air cleanerHeavy duty, dual-element CanisterAir cleaner system (HDAC)
Lubricating systemFull pressure
Ignition systemElectronic ignition system
Fuel systemEFI (electronic fuel injection) system
GovernorVariable speed governor
Fuel usedPropane
Starting systemElectric starter
PTO shaft rotationCounterclockwise (from PTO shaft side)
Dimensions (L x W X H)376 x 480 x 622 mm (14.8 x 18.9 x 24.5 in)
Dry weight49.0 kg (108.0 lbs)

Cylinder Block and Head

Cylinder block
Compression ratio:9.1:1
Cylinder bore:83.0 mm (3.27 in)
Piston stroke:69.0 mm (2.72 in)
Cylinder internal diameter (standard):83.006-83.031 mm (3.2680-3.2689 in)
Number of piston rings (compression / oil):2/1
Thrust face outer diameter (standard):82.978 mm (3.2668 in)
Piston pin diameter:16.995-17.000 mm (0.6691-0.6693 in)
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:35.955-35.973 mm (1.4155-1.4163 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 margin minimal (INTAKE):1.50 mm (0.0591 in)
Valve margin minimal (EXHAUST):1.50 mm (0.0591 in)
Camshaft journal diameter :19.920-19.975 mm (0.7843-0.7864 in)

Tightening torque specs

Tightening torque specs
Intake manifold mounting
(torque in 2 increments)
Step 1: 7.8 Nm (0.8 kg·m; 5.8 lb·ft)
Step 2: 10.5 Nm (1.1 kg·m; 7.7 lb·ft)
Connecting rod cap fastener13.6 Nm (1.4 kgf·m; 10.0 lb·ft)
Cylinder head Step 1: 16.9 Nm (1.72 kg·m; 12.5 lb·ft)
Step 2: 33.9 Nm (3.50 kg·m; 25.0 lb·ft)
Flywheel71.6 Nm (7.3 kgf·m; 52.8 lb·ft)
Muffler retaining nuts27.8 Nm (2.8 kgf·m; 20.5 lb·ft)
Spark plug27.0 Nm (2.75 kg·m; 20.0 lb·ft)

Service Data

Engine
Maximum speed:3600±50 rpm
Idle speed:1200±75 rpm
Oil system
Lubrication system:Full pressure
Oil type:API SJ, or higher
Recommended oil:SAE 10W-30, Kohler PRO 10W-50
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)
Ignition system
Type:Electronic ignition system
Spark plug:Champion RC12YC or Champion XC12YC
Spark plug gap:0.76 mm (0.030 in)
Ignition coil air gap0.280-0.330 mm (0.011-0.013 in)

References

1. Kohler Command PRO EFI PCH680, PCH740 service manual. Kohler Co. 2021.

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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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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