Kohler K181 (8.0 HP, 305 cc) Engine: Specs and Review


Kohler K181 Engine Specs

The Kohler K181 is an 18.6 cu·in (305 cc) single-cylinder air-cooled four-stroke internal combustion gasoline engine from K-series made by Kohler Co.

The Kohler K181 engine has a horizontal PTO shaft and an L-head (side valve) design.


This engine can be fitted with Kohler or Walbro carburetor, battery, magneto, or breakerless ignition systems.

The Kohler K181 engine used a paper air cleaner (an oiled foam pre-cleaner was available).

The cylinder bore is 2.94 in (74.62 mm), and the piston stroke is 2.75 in (69.85 mm). This engine delivered 8.2 PS (6.0 kW; 8.0 HP) at 3,600 rpm horsepower.

The breakdown of the Kohler K181 engine code is as follows:

  • K – K-series
  • 18 – Approximate displacement (cu·in)
  • 1 – Single cylinder
  • Suffix (engine is available with the following options):
  • S – Electric starter;
  • T – Retractable starter;
  • ST – Electric and retractable starter;
  • EP – Electric plant;
  • A – Special oil pan;
  • C – Clutch model;
  • G – Generator applications;
  • P – Pump model;
  • Q – Quled model;
  • R – Reduction gear;

Kohler K181 Engine Specs


Kohler K181 (8.0 HP, 305 cc) Engine Specs

Engine Specifications

Model K181
Type 4-stroke, L-head, single cylinder
Displacement 308 cm 3 (18.6 cu-in)
Max. horsepower 8.2 PS (6.0 kW; 8.0 HP) at 3,600 rpm
Max. torque (crank PTO)
Fuel system Carburetor (Kohler or Walbro, fixed main jet or adjustable main jet)
Cooling system Forced-air
Ignition system Magneto or battery or breakerless ignition system
Lubricating system Splash type
Starting system Recoil or electric starter
Fuel used Unleaded gasoline (octane number 86 or higher)

Cylinder Head

Valve Arrangement: L-head (sidevalve)
Valves: 2
Valve head diameter: INTAKE 34.925 mm (1.375 in)
EXHAUST 28.575 mm (1.125 in)
Stem outer diameter (standard): INTAKE 7.886-7.899 mm (0.3105-0.311 in)
EXHAUST 7.848-7.861 mm (0.309-0.3095 in)

Cylinder block

Compression ratio:
Bore x Stroke 74.62 X 69.85 mm (2.94 x 2.75 in)
Sleeve internal diameter 74.6252-74.5998 mm (2.938-2.937 in)
Piston skirt outer diameter 74.4143-74.3737 mm (2.9297-2.9281 in)
Number of piston rings (compression / oil): 2 / 1
Ring end gap Top 0.177-0.432 mm (0.007-0.017 in)
Second 0.177-0.432 mm (0.007-0.017 in)
Connecting rod small end ID 15.8877-15.8953 mm (0.6255-0.6258 in)
Piston pin outer diameter 15.8673-15.8724 mm (0.6247-0.6249 in)

Tightening torque specs

Cylinder head bolt 20-27 Nm; 2.0-2.7 kg·m; 15-20 ft·lb
Flywheel 115-122 Nm; 11.7-12.3 kg·m; 85-90 ft·lb
Spark plug 25-30 Nm; 2.55-3.06 kg·m; 18-22 ft·lb

Service Information

Max speed 3,600 rpm
Valve clearance
Intake valve clearance 0.15-0.20 mm (0.0059-0.0079 in)
Exhaust valve clearance 0.43-0.48 mm (0.0169-0.0189 in)
Oil system
Oil type API SF or SG
Recommended oil Summer: SAE 30W
Winter: SAE 5W-20, 5W-30
Oil capacity 1.2 L (1.27 US. qt, 1.06 Imp. qt.)
Ignition system
Spark plug Champion: RJ8C
Spark plug gap 0.65 mm (0.0256 in)

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Final Words

This concludes our discussion of the Kohler K181 (8.0 HP, 305 cc) Engine specs and review; however, if you have any questions regarding this article, please submit them in the comment section below. We will do our best to respond to you as soon as possible.


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