Kohler Command CH620

General Technical Data

Kohler CH620 Engine Specifications

Engine Model .................. Kohler Command CH620
Engine Type .................. 4-cycle V-Twin air-cooled gasoline
Number of Cylinders .................. 2
Displacement, cc (cu.in) .................. 624 (38.0)
Cylinder Bore, mm (in) .................. 77.0 (3.03)
Piston Stroke, mm (in) .................. 67.0 (2.64)
Rated Engine Power, hp (kW) .................. 18.0 (13.4)
Rated Engine Speed, rpm .................. 3600
Maximum Torque, Nm (ft-lbs) .................. 43.6 (32.2)
Torque Speed, rpm .................. 2200
Compression Ratio .................. 8.5:1
Lubrication System .................. Full pressure
Oil filter .................. Full-flow type
Air Cleaner .................. Replaceable, paper element
Oil Capacity, L (qts) .................. 1.8 (1.9)
Electrical System Rating, Volts .................. 12
Starter Type .................. Electric

Fuel System

Fuel System Type .................. Carburetor
Carburetor Model .................. Keihin
Carburetor Type .................. One-Barrel, fixed main jet
Fuel Pump Type .................. Pulse/mechanical
Fuel Filter Type .................. In-line
Governor Type .................. Mechanical

Dimensions and Weight

Overall Length, mm (in) .................. 349 (13.8)
Overall Width, mm (in) .................. 448 (17.7)
Overall Height, mm (in) .................. 481 (19.0)
Net Weight, kg (lbs) .................. 41.0 (90)

Kohler CH620 Maintenance Data

Engine Oil

Engine Oil Type (Summer Time) .................. SAE 10W-30
Engine Oil Type (Winter Time) .................. SAE 5W-30
Oil Classification (API Service) .................. SJ or higher
Oil Capacity (w/o Filter), L (qts) .................. 1.6 (1.7)
Oil Capacity (with New Filter), L (qts) .................. 1.8 (1.9)

Carburetor Adjustment

Main Fuel .................. 2-1/2 turns
Idle Fuel .................. 3/4 to 1 full turn
Low Idle Speed, rpm .................. 1200±75
High Idle Speed, rpm .................. 3600±50

Ignition System

Spark Plug Type .................. Champion RC12YC
Spark Plug Gap, mm (in) .................. 0.76 (0.030)
Module Air Gap, mm (in) .................. 0.28-0.33 (0.011-0.013)
Thread Size, mm (in) .................. 14 (0.55)
Reach, mm (in) .................. 19.1 (0.75)
Spark Plug Torque, Nm (ft-lbs) .................. 27 (20)

Service Intervals

Service Or Replace Low-Profile Precleaner .................. Every 25 hours
Replace Air Cleaner Element .................. Every 100 hours
Change Engine Oil .................. Every 100 hours
Clean Oil Cooler Fins .................. Every 100 hours
Change Oil Filter .................. Every 200 hours
Replace Fuel Filter .................. Every 200 hours
Check Carburetor Adjustment .................. Every 200 hours
Check and Adjust Valve Clearance .................. Every 500 hours
Check Spark Plug Condition and Gap .................. Every 500 hours
Replace Spark Plug .................. Every 500 hours

Kohler CH620 Service Specifications

Cylinder Block

Cylinder Bore Inside Diameter (Standard), mm (in) .................. 77.000-77.025 (3.0315-3.0325)
Cylinder Bore Inside Diameter (Wear Limit), mm (in) .................. 77.063 (3.0340)
Cylinder Bore (Max Out of Round), mm (in) .................. 0.12 (0.0047)
Cylinder Bore Max Taper, mm (in) .................. 0.05 (0.0020)
Connecting Rod to Crankpin Clearance, mm (in) .................. 0.030-0.055 (0.0012-0.0022)
Connecting Rod to Crankpin Side Clearance, mm (in) .................. 0.26-0.63 (0.0102-0.0248)
Connecting Rod to Piston Pin Clearance, mm (in) .................. 0.015-0.028 (0.0006-0.0011)
Connecting Rod Journal Outside Diameter, mm (in) .................. 35.955-35.973 (1.4156-1.4163)
Connecting Rod Journal Max Taper, mm (in) .................. 0.018 (0.0007)
Crankshaft End Play (Free), mm (in) .................. 0.070-0.590 (0.0028-0.0230)
Crankshaft Bore (Crankcase), mm (in) .................. 40.965-41.003 (1.6128-1.6143)
Crankshaft Bore (Closure Plate), mm (in) .................. 40.987-40.974 (1.6136-1.6131)
Crankshaft Bore to Crankshaft Clearance, mm (in) .................. 0.039-0.074 (0.0015-0.0029)
Crankshaft Bearing Journal Outside Diameter (Flywheel), mm (in) .............. 40.913-40.935 (1.6107-1.6116)
Crankshaft Bearing Journal Max Taper (Flywheel), mm (in) .................. 0.022 (0.0009)
Crankshaft Bearing Journal Outside Diameter (Closure Plate), mm (in) ......... 40.913-40.935 (1.6107-1.6116)
Crankshaft Bearing Journal Max Taper (Closure Plate), mm (in) .................. 0.022 (0.0009)
Crankshaft T.I.R (PTO End, Crank in Engine), mm (in) .................. 0.279 (0.0110)
Crankshaft T.I.R (Entire Crank, in V-Blocks), mm (in) .................. 0.10 (0.0039)

Cylinder Head and Valves

Cylinder Head (Max Out of Flatness), mm (in) .................. 0.076 (0.003)
Hydraulic Valve Lifter to Crankcase Clearance, mm (in) .................. 0.0241-0.0501 (0.0009-0.0020)
Intake Valve Stem to Valve Guide Clearance, mm (in) .................. 0.038-0.076 (0.0015-0.0030)
Exhaust Valve Stem to Valve Guide Clearance, mm (in) .................. 0.050-0.088 (0.0020-0.0035)
Intake Valve Guide Inside Diameter, mm (in) .................. 7.038-7.058 (0.2771-0.2779)
Exhaust Valve Guide Inside Diameter, mm (in) .................. 7.038-7.058 (0.2771-0.2779)
Valve Guide Reamer Size (Standard), mm (in) .................. 7.048 (0.2775)
Valve Guide Reamer Size (0.25 Oversize), mm (in) .................. 7.298 (0.2873)
Intake Valve Minimum Lift, mm (in) .................. 8.07 (0.3177)
Exhaust Valve Minimum Lift, mm (in) .................. 8.07 (0.3177)
Nominal Valve Face Angle, degrees .................. 45
Valve Seat Angle (Intake/Exhaust), degrees .................. 89
Intake Valve Insert Outside Diameter, mm (in) .................. 36.987-37.013 (1.4562-1.4572)
Exhaust Valve Insert Outside Diameter, mm (in) .................. 32.987-33.013 (1.2987-1.2997)
Intake Valve Guide Depth, mm (in) .................. 4.00 (0.1575)
Exhaust Valve Guide Depth, mm (in) .................. 6.50 (0.2559)
Intake Valve Head Diameter, mm (in) .................. 33.37-33.63 (1.3138-1.3240)
Exhaust Valve Head Diameter, mm (in) .................. 29.37-29.63 (1.1563-1.1665)
Intake Valve Stem Diameter, mm (in) .................. 6.982-7.000 (0.2749-0.2756)
Exhaust Valve Stem Diameter, mm (in) .................. 6.970-6.988 (0.2744-0.2751)
Camshaft End Play, mm (in) .................. 0.076-0.127 (0.0030-0.0050)
Camshaft Clearance, mm (in) .................. 0.025-0.063 (0.0010-0.0025)
Camshaft Bore Inside Diameter, mm (in) .................. 20.000-20.025 (0.7874-0.7884)
Camshaft Bearing Outside Diameter, mm (in) .................. 19.962-19.975 (0.7859-0.7864)

Piston and Piston Rings

Piston to Piston Pin Clearance, mm (in) .................. 0.006-0.017 (0.0002-0.0007)
Piston Pin Bore Inside Diameter, mm (in) .................. 17.006-17.012 (0.6695-0.6698)
Piston Pin Outside Diameter, mm (in) .................. 16.995-17.000 (0.6691-0.6693)
Top Compression Ring Groove Clearance, mm (in) .................. 0.040-0.080 (0.0016-0.0031)
Middle Compression Ring Groove Clearance, mm (in) .................. 0.040-0.080 (0.0016-0.0031)
Oil Control Ring Groove Clearance, mm (in) .................. 0.060-0.202 (0.0024-0.0080)
Top and Middle Compression Ring End Gap, mm (in) .................. 0.25-0.45 (0.0100-0.0177)
Piston Thrust Face Outside Diameter (Std), mm (in) .................. 76.967-76.985 (3.0302-3.0309)
Piston Thrust Face Outside Diameter (Wear Limit), mm (in) .................. 76.840 (3.0252)
Piston Thrust Face to Cylinder Bore Clearance, mm (in) .................. 0.014-0.057 (0.0005-0.0022)

Tightening Torque Specs

Cylinder Head Nut, Nm (ft-lb) .................. 16.9-33.9 (12.5-25.1)
Cylinder Head Bolt, Nm (ft-lb) .................. 22.6-41.8 (16.7-30.8)
Rocker Arm Screw, Nm (ft-lb) .................. 11.3 (8.3)
Connecting Rod Cap, Nm (ft-lb) .................. 11.3 (8.3)
Flywheel Retaining Screw, Nm (ft-lb) .................. 66.4 (49.1)
Intake Manifold Mounting, Nm (ft-lb) .................. 7.4 (5.5)
Carburetor Mounting Nut, Nm (ft-lb) .................. 6.2-7.3 (4.6-5.4)
Closure Plate, Nm (ft-lb) .................. 24.4 (18.1)
Oil Drain Plug, Nm (ft-lb) .................. 13.6 (10.1)
Governor Lever Nut, Nm (ft-lb) .................. 6.8 (5.1)
Ignition Module, Nm (ft-lb) .................. 4.0-6.2 (2.9-4.6)
Muffler Retaining Nut, Nm (ft-lb) .................. 24.4 (18.1)
Fuel Pump Screw, Nm (ft-lb) .................. 2.3 (1.7)
Spark Plug, Nm (ft-lb) .................. 27 (20.1)