Kohler LH630

Kohler LH630The Kohler LH630 is a 624 cc (38.1 cu·in) natural aspirated V-twin four-stroke liquid-cooled internal combustion small gasoline engine with a horizontal shaft from the Aegis series, manufactured by Kohler Co for general-purpose applications.

It has an 77.0 mm (3.03 in) cylinder bore and 67.0 mm (2.64 in) piston stroke. The compression ratio rating is 8.5:1.

This engine produced 22.3 PS (16.4 KW; 22.0 HP) at 3,600 rpm of maximum horsepower and 48.0 Nm (4.9 kg·m; 35.42 ft·lb) at 2,200 rpm of peak torque.

The Kohler Aegis LH630 features:

  • OHV (overhead valve) design
  • Hydraulic valve system
  • Electronic ignition system
  • One-barrel carburetor with fixed main jet (Keihin)
  • Centrifugal flyweight mechanical governor
  • Full pressure with Gerotor oil pump lubrication system
  • Liquid-cooled cooling system with parallel-flow radiator and integrated belt-driven water pump
  • Solenoid shift starter (12V)

General information

Engine Specifications
Engine model Aegis LH630
Engine type 4-stroke, OHV, V-twin
Displacement 624 cm3, (38.1 cu·in)
Max. horsepower 22.3 PS (16.4 KW; 22.0 HP) at 3,600 rpm
Max. torque 48.0 Nm (4.9 kg·m; 35.42 ft·lb) at 2,200 rpm
Cooling system Liquid-cooled
Air cleaner Heavy-Duty air cleaner
Lubricating system Full pressure with gerotor oil pump
Ignition system Electronic ignition system
Fuel system Carburetor with fixed main jet (Keihin)
Fuel used Unleaded gasoline (octane number 86 or higher)
Starting system Solenoid shift starter (12V)
Charging system 20A charging, regulated
Governor Centrifugal flyweight mechanical governor
PTO shaft rotation Counterclockwise (from PTO shaft side)
Dimensions (L x W X H) 432 x 459 x 674 mm (17.0 x 18.1 x 26.5 in)
Dry weight 51.7 kg (114.0 lbs)

Cylinder Block and Head

Cylinder block
Compression ratio: 8.5:1
Cylinder bore: 77.0 mm (3.03 in)
Piston stroke: 67.0 mm (2.64 in)
Cylinder internal diameter (standard): 77.000-77.025 mm (3.0315-3.0325 in)
Piston skirt outer diameter (standard): 76.968-76.986 mm (3.0302-3.0309 in)
Number of piston rings (compression / oil): 2/1
Connecting rod small end diameter (standard): 17.015-17.023 mm (0.6699-0.6702 in)
Piston pin diameter: 16.995-17.000 mm (0.6691-0.6693 in)
Side clearance (Top): 0.040-0.086 mm (0.0016-0.0034 in)
Side clearance (Second): 0.040-0.086 mm (0.0016-0.0034 in)
Side clearance (Oil): 0.046-0.196 mm (0.0018-0.0077 in)
Ring end gap (Top): 0.180-0.380 mm (0.0071-0.0150 in)
Ring end gap (Second): 0.250-0.450 mm (0.0098-0.0177 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)
Crankshaft center distance: 33.5 mm (1.32 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 face angle (INTAKE): 45°
Valve face angle (EXHAUST): 45°
Seat angle (INTAKE): 89°
Seat angle (EXHAUST): 89°
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 (min) (INTAKE): 8.88 mm (0.3496 in)
Valve lift (min) (EXHAUST): 8.88 mm (0.3496 in)
Camshaft journal diameter : 19.962-19.975 mm (0.7859-0.7864 in)

Tightening torque specs

Tightening torque specs
Intake manifold (torque in 2 increments) Step 1: 7.4 Nm (0.8 kgf·m; 5.5 lb·ft)
Step 2: 9.9 Nm (1.0 kgf·m; 7.3 lb·ft)
Carburetor mounting 9.9 Nm (1.0 kgf·m; 7.3 lb·ft)
Connecting rod cap 11.3 Nm (1.15 kg·m; 8.3 ft·lb)
Oil drain plugs 13.6 Nm (1.4 kg·m; 10.0 ft·lb)
Cylinder head (torque in 2 increments) Step 1: 16.9 Nm (1.7 kg·m; 12.5 ft·lb)
Step 2: 33.9 Nm (3.5 kg·m; 25.0 ft·lb)
Rocker pivot 11.3 Nm (1.1 kg·m; 8.34 ft·lb)
Rear fan shaft to mounting bracket nut 15.8 Nm (1.6 kgf·m; 11.7 lb·ft)
Front fan assembly to fan shaft nut 15.8 Nm (1.6 kgf·m; 11.7 lb·ft)
Flywheel 66.4 Nm (6.77 kg·m; 49 ft·lb)
Spark plug 27 Nm (2.75 kg·m; 19.93 ft·lb)
Muffler retaining nuts 24.4 Nm (2.5 kg·m; 18.0 ft·lb)
Valve cover 6.2 Nm (0.63 kg·m; 4.6 ft·lb)
Governor lever nut 6.8 Nm (0.7 kgf·m; 5.0 lb·ft)

Service Data

Idle speed: 1200±75 rpm
Compression pressure
Compression differential limit between cylinders: 15% and less
Oil system
Lubrication system: Full pressure with gerotor oil pump
Oil type: SAE 10W-30
Recommended oil: API SG, SH, SJ, or higher
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)
Ignition system
Type: Electronic ignition system
Spark plug: Champion RC14YC or Kohler 6613201-S
Spark plug gap: 0.76 mm (0.030 in)
Spark plug torque: 27 N·m (2.8 kg·m, 19.9 ft·lb)
Ignition module air gap: 0.20-0.30 mm (0.008-0.012 in)
Cooling system
Cooling system: Liquid-cooled cooling system with parallel-flow radiator and integrated belt-driven water pump
Coolant capacity: 2.0 liters (2.1 US.qts, 1.8 Imp. qts)


1. Kohler Aegis LH630, LH640, LH685, LH690, LH750, LH755 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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