Kohler K321

Kohler K321The Kohler K321 is a 512 cc, (31.2 cu·in) natural aspirated single-cylinder four-stroke air-cooled internal combustion small gasoline engine with a horizontal shaft, manufactured by Kohler Co, for general-purpose applications.

Cylinder bore and piston stroke are 88.9 mm (3.5 in) and 82.6 mm (3.25 in), respectively. This engine produced 14.1 PS (10.4 kW; 14.0 HP) at 3,600 rpm of horsepower.

The Kohler K321 features:

  • L-head (side valve) design
  • Magneto ignition system, battery ignition system, breakerless ignition system ignition system*
  • Carburetor (Kohler or Walbro – fixed main jet or adjustable main jet)*
  • Centrifugal governor
  • Splash type lubrication system
  • Forced air cooling system
  • Retractable and electric starter

* – depending on modification

General information

Engine Specifications
Engine modelK321
Engine type4-stroke, L-head (side valve), single-cylinder
Displacement512 cm3, (31.24 cu·in)
Max. horsepower14.1 PS (10.4 kW; 14.0 HP) at 3,600 rpm
Max. torque
Cooling systemForced air
Air cleanerPaper air cleaner (oiled foam precleaner)
Lubricating systemSplash type
Ignition systemMagneto ignition system, battery ignition system, breakerless ignition system
Fuel systemCarburetor (Kohler or Walbro – fixed main jet or adjustable main jet)
Fuel consumption
Fuel tank capacity
Fuel usedUnleaded gasoline (octane number 86 or higher)
Starting systemRetractable or electric starter
GovernorCentrifugal governor
PTO shaft rotationCounterclockwise (from PTO shaft side)
Dimensions (L x W X H)
Dry weight53.5 kg (117.9 lbs)

Cylinder Block and Head

Cylinder block
Compression ratio:
Cylinder bore:88.9 mm (3.5 in)
Piston stroke:82.6 mm (3.25 in)
Cylinder internal diameter (standard):88.9127-88.8873 mm (3.5005-3.4995 in)
Piston skirt outer diameter (standard):88.7501-88.7425 mm (3.4941-3.4938 in)
Number of piston rings (compression / oil):2/1
Connecting rod small end diameter (standard):22.2428-22.2504 mm (0.8757-0.876 in)
Piston pin diameter:22.2300-22.2352 mm (0.8752-0.8754 in)
Ring end gap (Top):0.177-0.432 mm (0.007-0.017 in)
Ring end gap (Second):0.177-0.432 mm (0.007-0.017 in)
Crankshaft center distance:41.3 mm (1.625 in)
Cylinder head
Valve arrangement:L-head (side valve), belt driven
Valve head diameter (INTAKE):34.798-35.052 mm (1.37-1.38 in)
Valve head diameter (EXHAUST): 28.448-28.702 mm (1.12-1.13 in)
Suffix “D” and later: 34.798-35.052 mm (1.370-1.380 in)
Valve steam diameter (INTAKE):7.8867-7.8994 mm (0.3105-0.311 in)
Valve steam diameter (EXHAUST):7.8334-7.8511 mm (0.3084-0.3091 in)

Tightening torque

Tightening torque specs
Cylinder head bolts34-41 Nm (25-30 ft-lbs)
Flywheel68-81 Nm (50-60 ft-lbs)
Spark plug25-30 Nm (18-22 ft-lbs)
Connecting rod32.1 Nm (23.8 ft-lbs)
Governor bushing11.2-13.6 Nm (8.3-10.1 ft-lbs)
Fuel pump mounting screws4.2-5.1 Nm (3.1-3.8 ft-lbs)

Service Data

Maximum speed:3,600 rpm
Valve clearance
Intake valve clearance:0.20-0.25 mm (0.0079-0.0098 in)
Exhaust valve clearance:0.43-0.48 mm (0.0169-0.0189 in)
Oil system
Lubrication system:Splash type
Oil type:SF or SG
Recommended oil: Summer: SAE 30W
Winter: SAE 5W-20, 5W-30
Oil capacity: K321: 1.9 L (2.01 US. qt, 1.67 Imp. qt.)
K321A: 1.2 L (1.27 US. qt, 1.06 Imp. qt.)
Fuel system
Type:Carburetor (Kohler or Walbro – fixed main jet or adjustable main jet)
Ignition system
Type:Magneto ignition system, battery ignition system, breakerless ignition system
Spark plug:Champion RH10
Spark plug gap:0.65 mm (0.0256 in)
Spark plug torque:27 N·m (2.8 kg·m, 19.9 ft·lb)


Manufacturer or BrandModels
Lawn tractors
Cub Cadet147, 149, 1450
J.I.Case444 (1969-1976), 444 (1977-1985)>
John Deere140, 214, 314
Wheel HorseGT-14


1. Kohler K91, K141, K161, K181, K241, K301, K321, K341, service manual. Kohler Co. 1992.

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.

ATTENTION! Dear visitors, this is an informational database of technical specifications, we are not a parts supplier or a marketplace.

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.

1 Comment

  1. Hi , I have an older bobcat 371 skid steer. It has a Kohler k321 14 hp . I would like to upgrade the motor to a new one ( relatively cheap $ ) concerned about shaft size , key etc. Can you recommend a plug and play option for me. Much appreciated, Gerry Corridon

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