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Kohler K181S Engine

General Technical Data

Kohler K181S Engine Specifications

Engine Model ............... Kohler K181S
Engine Type ............... 4-Cycle, one cylinder air-cooled gasoline
Number of Cylinders ............... Single
Displacement, L (cu in) ............... 0.308 (18.6)
Engine Bore, mm (in) ............... 74.6 (2.94)
Engine Stroke, mm (in) ............... 69.9 (2.75)
Maximum Horse Power, hp (kW) ............... 8.0 (6.0)
Rated Engine Speed, rpm ............... 3600
Fuel System ............... Carburetor
Carburetor Model ............... Kohler/Walbro
Carburetor Type ............... Fixed main jet or adjustable main jet
Lubrication System ............... Splash type
Cooling System ............... Forced-air
Ignition System ............... Magneto or battery
Starter Type ............... Electric Starter

Kohler K181S Maintenance Data

Engine Oil Type (Summer) ............... SAE 30W
Engine Oil Type (Winter) ............... SAE 5W-20, 5W-30
Oil Classification ............... API SF or SG
Oil Capacity, L (qts) ............... 1.21 (1.26)
Spark Plug Type ............... Champion RJ8C
Spark Plug Gap, mm (in) ............... 0.65 (0.0256)
Valve Clearance (Intake), mm (in) ............... 0.15-0.20 (0.0059-0.0079)
Valve Clearance (Exhaust), mm (in) ............... 0.43-0.48 (0.0169-0.0189)

Service Intervals

Engine Oil Changing ............... Every 25 hours
Clean Air Cleaner Paper Element ............... Every 100 hours
Checking Spark Plug ............... Every 100 hours
Fuel Filter Replacement ............... As required
Valve Clearance Adjustment ............... Every 500 hours

Carburetor Tune-Up

Low Idle (Kohler/Walbro) ............... 1-1/4 turns / 1-1/2 turns
High Idle (Kohler/Walbro) ............... 2 turns / 3/4 turns

Kohler K181S Service Data

Cylinder Block

Sleeve Internal Diameter, mm (in) ............... 74.6252-74.5998 (2.938-2.937)
Piston Skirt Outer Diameter, mm (in) ............... 74.4143-74.3737 (2.9297-2.9281)
Top Compression Ring End Gap, mm (in) ............... 0.177-0.432 (0.007-0.017)
Second Compression Ring End Gap, mm (in) ............... 0.177-0.432 (0.007-0.017)
Connecting Rod Small End Inside Diameter, mm (in) ............... 15.8877-15.8953 (0.6255-0.6258)
Piston Pin Outside Diameter, mm (in) ............... 15.8673-15.8724 (0.6247-0.6249)

Cylinder Head and Valves

Intake Valve Head Diameter, mm (in) ............... 34.925 (1.375)
Exhaust Valve Head Diameter, mm (in) ............... 28.575 (1.125)
Stem Outside Diameter (Intake, Std), mm (in) ............... 7.886-7.899 (0.3105-0.311)
Stem Outside Diameter (Exhaust, Std), mm (in) ............... 7.848-7.861 (0.309-0.3095)
Valve Guide Inside Diameter (Intake, Exhaust), mm (in) ............... 7.894-7.919 (0.312-0.313)
Valve Seat Angle (Intake, Exhaust), degrees ............... 89
Valve Seat Width (Intake), mm (in) ............... 0.936-1.139 (0.037-0.045)
Valve Seat Width (Exhaust), mm (in) ............... 0.936-1.139 (0.037-0.045)
Valve Guide Depth (Intake, Exhaust), mm (in) ............... 33.194 (1.312)
Valve Face Angle (Intake, Exhaust), degrees ............... 45

Crankshaft

Crankpin Diameter, mm (in) ............... 30.01 (1.186)
Crankshaft Main Bearing Journal Diameter, mm (in) ............... 29.88 (1.181)
Crankshaft Oil Seal Journal Diameter (Front), mm (in) ............... 28.46 (1.125)
Crankshaft Oil Seal Journal Diameter (Rear), mm (in) ............... 28.46 (1.125)

Kohler K181S Tightening Torque Specifications

Cylinder Head Bolts, Nm (ft-lbs) ............... 20-27 (15-20)
Flywheel, Nm (ft-lbs) ............... 115-122 (85-90)
Spark Plug, Nm (ft-lbs) ............... 25-30 (18-22)
Connecting Rod, Nm (ft-lbs) ............... 22.5 (16.7)
Governor Bushing, Nm (ft-lbs) ............... 14.6-16.9 (10.8-12.5)
Fuel Pump Mounting Screws, Nm (ft-lbs) ............... 4.2-5.1 (3.1-3.8)