Kohler LH685

Kohler LH685The Kohler LH685 is a 674 cc, (41.1 cu·in) V-twin liquid-cooled four-stroke internal combustion gasoline engine from the Aegis series, manufactured by Kohler Co.

The Kohler LH685 engine has an OHV (overhead valve) design, horizontal PTO-shaft, pressurized lubrication system with oil pump. This engine is equipped with a one-barrel carburetor (Keihin) with a fixed main jet and electronic ignition system.

It has an 80.0 mm (3.15 in) cylinder bore and 67.0 mm (2.64 in) piston stroke. The compression ratio rating is 8.5:1. This engine produced 25.3 PS (18.6 KW; 25.0 HP) at 3,600 rpm of horsepower and 54.3 Nm (5.54 kg·m; 40.07 ft·lb) at 2,200 rpm of peak torque.

The breakdown of the engine code is as follows:

  • L – Liquid-cooled
  • H – Horizontal PTO shaft
  • 685 – Numerical designation

General information

Engine Specifications
ModelAEGIS LH685
Type4-stroke, OHV, V-twin
Displacement674 cm 3 (41.1 cu-in)
Max. horsepower25.3 PS (18.6 KW; 25.0 HP) at 3,600 rpm
Max. torque54.3 Nm (5.54 kg·m; 40.07 ft·lb) at 2,200 rpm
Fuel systemOne-barrel carburetor with a fixed main jet (Keihin)
Cooling systemLiquid-cooled
Ignition systemElectronic ignition system
Lubricating systemPressurized lubrication
Starting systemElectric starter
Fuel usedUnleaded gasoline (octane number 86 or higher)

Cylinder Block and Head

Cylinder block
Compression ratio:8.5:1
Bore x Stroke80.0 X 67.0 mm (3.15 x 2.64 in)
Sleeve internal diameter80.000-80.025 mm (3.1496-3.1506 in)
Number of piston rings (compression / oil):2 / 1
Piston type A
Piston skirt outer diameter79.963-79.981 mm (3.1481-3.1488 in)
Connecting rod small end ID17.006-17.013 mm (0.6695-0.6698 in)
Piston pin outer diameter16.995-17.000 mm (0.6691-0.6693 in)
Side clearance:Top0.050-0.096 mm (0.0020-0.0038 in)
Second0.030-0.076 mm (0.0012-0.0030 in)
Oil0.046-0.196 mm (0.0018-0.0077 in)
Ring end gap:Top0.180-0.430 mm (0.0071-0.0169 in)
Second0.250-0.460 mm (0.0098-0.0181 in)
Piston type B
Piston skirt outer diameter79.966 mm (3.1483 in)
Connecting rod small end ID17.006-17.013 mm (0.6695-0.6698 in)
Piston pin outer diameter16.995-17.000 mm (0.6691-0.6693 in)
Side clearance:Top0.030-0.070 mm (0.0010-0.0026 in)
Second0.030-0.070 mm (0.0010-0.0026 in)
Oil0.060-0.190 mm (0.0022-0.0073 in)
Ring end gap:Top0.100-0.279 mm (0.0039-0.0110 in)
Second1.400-1.679 mm (0.0551-0.0661 in)
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 drive
Valves:4 (2 per cylinder)
Valve head diameter:INTAKE33.370-33.630 mm (1.3138-1.324 in)
EXHAUST29.370-29.630 mm (1.1563-1.1665 in)
Stem outer diameter:INTAKE6.982-7.000 mm (0.2749-0.2756 in)
EXHAUST6.970-6.988 mm (0.2744-0.2751 in)

Tightening torque specs

Tightening torque specs
Cylinder head bolt Step 1: 16.9 Nm (1.72 kg·m; 12.47 ft·lb)
Step 2: 33.9 Nm (3.46 kg·m; 25.02 ft·lb)
Flywheel66.4 Nm (6.77 kg·m; 49.0 ft·lb)
Spark plug27 Nm (2.75 kg·m; 20.0 ft·lb)

Service Information

Oil system
Oil typeAPI SG, SH, SJ, or higher
Recommended oilSAE 10W-30
Oil capacity W/o oil filter: 1.6 liters (1.7 US.qts, 1.4 Imp. qts)
With oil filter: 1.8 liters (1.9 US.qts, 1.58 Imp. qts)
Cooling system
TypePressurized cooling system with integrated belt-driven water pump
Coolant capacity2.0 liters (2.1 US.qts, 1.8 Imp. qts)
Ignition system
Spark plugChampion RC14YC
Spark plug gap0.76 mm (0.030 in)
Ignition module air gap0.2-0.3 mm (0.008-0.012 in)
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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