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Kohler K321 Engine

General Technical Data

Kohler K321 Engine Specifications

Engine Model ............... Kohler K321 (K321AQS)
Engine Type ............... 4-Cycle, one cylinder air-cooled gasoline
Number of Cylinders ............... Single
Displacement, L (cu in) ............... 0.512 (31.3)
Engine Bore, mm (in) ............... 89.0 (3.50)
Engine Stroke, mm (in) ............... 82.6 (3.25)
Maximum Horse Power, hp (kW) ............... 14.0 (10.5)
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 ............... Recoil or electric

Kohler K321 Maintenance Data

Engine Oil

Engine Oil Type (Summer) ............... SAE 30W
Engine Oil Type (Winter) ............... SAE 5W-20, 5W-30
Oil Classification ............... API SF, SG
Oil Capacity (K321), L (qts) ............... 1.90 (2.02)
Oil Capacity (K321AQS Special Oil Pan), L (qts) ............... 2.21 (2.26)

Ignition System

Spark Plug Type ............... Champion RH10
Spark Plug Size, mm (in) ............... 14.0 (0.553)
Spark Plug Gap, mm (in) ............... 0.65 (0.0256)
Breaker Point Gap (Nominal), mm (in) ............... 0.50 (0.020)

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

Kohler Adjustable Jet (Low Idle) ............... 2-1/2 turns
Kohler Adjustable Jet (High Idle) ............... 3-1/4 turns
Walbro Fixed Jet (Low Idle) ............... 1-1/2 turns
Walbro Adjustable Jet (Low Idle) ............... 1-1/8 turns
Walbro Adjustable Jet (High Idle) ............... 1-1/4 turns

Kohler K321 Service Data

Valves

Valve Clearance (Intake), mm (in) ............... 0.20-0.25 (0.0079-0.0099)
Valve Clearance (Exhaust), mm (in) ............... 0.43-0.48 (0.0169-0.0189)
Intake Valve Head Diameter, mm (in) ............... 34.798-35.052 (1.370-1.380)
Exhaust Valve Head Diameter, mm (in) ............... 28.448-28.702 (1.120-1.130)
Stem Outside Diameter (Intake, Std), mm (in) ............... 7.887-7.899 (0.3105-0.3110)
Stem Outside Diameter (Exhaust, Std), mm (in) ............... 7.833-7.851 (0.3084-0.3091)
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), mm (in) ............... 40.126 (1.586)
Valve Guide Depth (Exhaust), mm (in) ............... 37.874 (1.497)
Valve Face Angle (Intake, Exhaust), degrees ............... 45

Cylinder Block

Sleeve Internal Diameter, mm (in) ............... 88.9127-88.8873 (3.5005-3.4995)
Piston Skirt Outside Diameter, mm (in) ............... 88.7501-88.7425 (3.4941-3.4938)
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) ............... 22.2428-22.2504 (0.8757-0.876)
Piston Pin Outside Diameter, mm (in) ............... 22.2300-22.2352 (0.8752-0.8754)

Kohler K321 Tightening Torque Specifications

Cylinder Head Bolts, Nm (ft-lbs) ............... 34-41 (25-30)
Flywheel, Nm (ft-lbs) ............... 68-81 (50-60)
Spark Plug, Nm (ft-lbs) ............... 25-30 (18-22)
Connecting Rod, Nm (ft-lbs) ............... 32.1 (23.8)
Governor Bushing, Nm (ft-lbs) ............... 11.2-13.6 (8.3-10.1)
Fuel Pump Mounting Screws, Nm (ft-lbs) ............... 4.2-5.1 (3.1-3.8)