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Onan CCKB Engine

General Technical Data

Onan CCKB Engine Specifications

Engine Model .................... Onan CCKB
Engine Type .................... Gasoline, 4-cycle, two cylinder L-head air-cooled
Number of Cylinders .................... 2
Engine Bore, in (mm) .................... 3.25 (82.6)
Piston Stroke, in (mm) .................... 3.00 (76.2)
Total Displacement, cu. in (cm3) .................... 49.8 (816)
Rated Power, Hp (kW) .................... 20.0 (14.9)
Maximum Speed, rpm .................... 3900
Low Idle Speed, rpm .................... 1500-1550
Compression Ratio .................... 7:1
Crankshaft Alignment .................... Horizontal
Cylinder Material .................... Aluminum
Lubricating System .................... Full pressure
Oil Filter Type .................... Full flow
Ignition System .................... Battery
Electrical System Rating .................... 12V

Fuel System

Fuel System Type .................... Carburetor
Carburetor .................... Side draft type
Fuel Pump Type .................... Diaphragm
Governor Type .................... Adjustable mechanical flyball

Dimensions

Overall Length, in (mm) .................... 15.1 (382)
Overall Width, in (mm) .................... 20.5 (518)
Overall Height, in (mm) .................... 23.0 (580)
Dry weight, lbs (kg) .................... 150 (69)

Onan CCKB Maintenance Data

Engine Oil

Engine Oil Type (Summer Time) .................... SAE 30
Engine Oil Type (Winter Time) .................... SAE 5W-30
Oil Classification .................... API SE or CC
Oil Capacity (w/o Filter), qt (L) .................... 3.5 (3.3)
Oil Capacity (with Filter), qt (L) .................... 4.0 (3.8)

Cylinder Block and Valves

Cylinder Bore I.D. (Maximum), in (mm) .................... 3.255 (82.677)
Cylinder Head (Max. Out of Flatness), in (mm) .................... 0.004 (0.1)
Intake Valve Clearance (Cold), in (mm) .................... 0.007 (0.18)
Exhaust Valve Clearance (Cold), in (mm) .................... 0.016 (0.41)

Carburetor Adjustment

Main Fuel .................... 2 to 3
Idle Fuel .................... 1-1/2
Low Idle Speed, rpm .................... 1500±50
High Idle Speed, rpm .................... 3850±100

Service Intervals

Clean Governor Linkage .................... Every 50 hours
Service Air Cleaner .................... Every 100 hours
Change Engine Oil .................... Every 100 hours
Clean Fuel Filter .................... Every 100 hours
Change Oil Filter .................... Every 200 hours
Replace Spark Plug .................... Every 200 hours
Inspect Breaker Point .................... Every 200 hours
Check and Adjust Valve Clearance .................... Every 500 hours

Ignition System

Ignition Timing, deg .................... 24 BTC
Spark Plug Type .................... Champion RH8C
Spark Plug Gap, in (mm) .................... 0.025 (0.64)
Breaker Point Gap, in (mm) .................... 0.020 (0.51)
Plug Hex Size, in (mm) .................... 0.81 (20.6)
Spark Plug Torque, Nm (ft-lbs) .................... 33-38 (25-28)

Onan CCKB Service Data

Cylinder Block

Cylinder Bore Honed Diameter, in (mm) .................... 3.2490-3.2500 (82.53-82.55)
Main Bearing Inside Diameter (Without bearing), in (mm) .................... 2.187-2.188 (55.55-55.58)
Main Bearing inside Diameter (Installed), in (mm) .................... 2.0015-2.0040 (50.84-50.90)
Camshaft Bearing Bore (Bearing installed), in (mm) .................... 1.376-1.377 (34.95-34.98)
Camshaft Bearing Journal Diameter, in (mm) .................... 1.3740-1.3745 (34.90-34.91)
Camshaft Bearing Clearance, in (mm) .................... 0.0015-0.0030 (0.038-0.076)
Camshaft End Play, in (mm) .................... 0.0030 (0.076)
Camshaft Lift, in (mm) .................... 0.300 (7.62)

Cylinder Head and Valves

Intake Valve Stem Diameter, in (mm) .................... 0.3425-0.3430 (8.70-8.71)
Exhaust Valve Stem Diameter, in (mm) .................... 0.3410-0.3415 (8.661-8.674)
Intake Valve Clearance (Stem to Guide), in (mm) .................... 0.0010-0.0025 (0.025-0.064)
Exhaust Valve Clearance (Stem to Guide), in (mm) .................... 0.0025-0.040 (0.064-0.102)
Intake/Exhaust Valve Face Angle, degrees .................... 44
Intake/Exhaust Valve Seat Width, in (mm) .................... 0.031-0.047 (0.787-1.194)
Intake/Exhaust Valve Seat Angle, degrees .................... 45
Exhaust Valve Seat Cylinder Head Bore Diameter, in (mm) .................... 1.189-1.190 (30.20-30.23)
Exhaust Valve Seat Outside Diameter, in (mm) .................... 1.192-1.193 (30.28-30.30)
Valve Guide Inside Diameter, in (mm) .................... 0.344-0.345 (8.74-8.76)
Tappet Body Diameter, in (mm) .................... 0.7475-0.7480 (18.99-19.00)
Tappet Bore Diameter, in (mm) .................... 0.7505-0.7515 (19.06-19.09)
Tappet Clearance in Bore, in (mm) .................... 0.0015-0.003 (0.038-0.076)
Valve Spring Free Length, in (mm) .................... 1.662 (42.21)
Valve Spring Length (Open), in (mm) .................... 1.125 (28.58)
Valve Spring Length (Closed), in (mm) .................... 1.375 (34.93)

Crankshaft and Connecting Rod

Crankshaft Main Bearing Journal Diameter, in (mm) .................... 1.9992-2.0000 (50.78-50.80)
Crankshaft Main Bearing Clearance, in (mm) .................... 0.0025-0.0038 (0.064-0.097)
Connecting Rod Journal Diameter, in (mm) .................... 1.6252-1.6260 (41.28-41.30)
Crankshaft End Play, in (mm) .................... 0.006-0.012 (0.15-0.30)
Connecting Rod Large Bore Diameter, in (mm) .................... 1.7505-1.7510 (44.46-44.48)
Connecting Rod Side Clearance, in (mm) .................... 0.002-0.016 (0.051-0.406)
Piston Pin Bushing Bore (Without bearing), in (mm) .................... 0.8115-0.8125 (20.61-20.64)
Piston Pin Bushing Bore (Finished bore), in (mm) .................... 0.7504-0.7508 (19.05-19.07)
Bearing to Crankshaft Clearance (Aluminum Rod), in (mm) .................... 0.0020-0.0033 (0.051-0.084)

Piston and Piston Rings

Piston Clearance in Cylinder, in (mm) .................... 0.006-0.008 (0.15-0.20)
Piston Pin Bore, in (mm) .................... 0.7502-0.7506 (19.055-19.065)
Top 1 Compression Ring Groove Width, in (mm) .................... 0.0960-0.0970 (2.438-2.464)
Top 2 Compression Ring Groove Width, in (mm) .................... 0.0955-0.0965 (2.426-2.451)
Oil Control Ring Groove Width, in (mm) .................... 0.188-0.189 (4.775-4.801)
Piston Pin Clearance in Connecting Rod, in (mm) .................... 0.0002-0.0007 (0.005-0.018)
Piston Pin Diameter, in (mm) .................... 0.7500-0.7502 (19.05-19.06)
Top Ring Groove Clearance, in (mm) .................... 0.002-0.008 (0.051-0.203)
Ring End Gap in Cylinder Clearance, in (mm) .................... 0.010-0.020 (0.254-0.508)

Onan CCKB Tightening Torque Specs

Cylinder Head Cap Screw, ft-lb (Nm) .................... 29-31 (39-42)
Rear Bearing Plate, ft-lb (Nm) .................... 20-25 (27-34)
Connecting Rod Bolt, ft-lb (Nm) .................... 24-26 (33-35)
Flywheel Cap Screw, ft-lb (Nm) .................... 35-40 (48-54)
Starter Mounting Bolts, ft-lb (Nm) .................... 25-35 (34-47)
Gear Case Cover, ft-lb (Nm) .................... 10-13 (14-18)
Spark Plug Torque, ft-lb (Nm) .................... 25-28 (33-38)
Oil Pump, ft-lb (Nm) .................... 7-9 (10-12)
Intake Manifold Mounting Screws, ft-lb (Nm) .................... 15-20 (20-27)
Exhaust Manifold Mounting Screws, ft-lb (Nm) .................... 14-17 (19-23)
Oil Base, ft-lb (Nm) .................... 43-48 (58-65)