Onan P220G

Onan P220GThe Onan P220G is a 782 cc, (47.7 cu·in) natural aspirated two-cylinders four-stroke air-cooled internal combustion small gasoline engine with a horizontal shaft, manufactured by Onan for general-purpose applications.

The cylinder bore is 82.55 mm (3.25 in) and the piston stroke is 73.00 mm (2.87 in). The compression ratio rating is 7.0:1.

The Onan P220G engine produced 20.3 PS (14.9 kW; 20.0 HP) at 3,600 rpm of maximum output power.

The Onan P220G features:

  • L-haed design
  • Electronic battery ignition system
  • Carburetor with fixed main jet
  • Centrifugal governor
  • Full pressure with oil filter lubrication system
  • Forced air cooling system
  • Electric starter 12V

General information

Engine Specifications
Engine model P220G Performer 20
Engine type 4-stroke, L-head, two-cylinders
Displacement 782 cm3, (47.7 cu·in)
Max. horsepower 20.3 PS (14.9 kW; 20.0 HP) at 3,600 rpm
Cooling system Forced air
Lubricating system Full pressure with oil filter
Ignition system Electronic battery
Fuel system Carburetor with fixed main jet
Fuel used Unleaded gasoline (octane number 86 or higher)
Starting system Electric starter 12V
Stoping system Ignition primary circuit ground
Governor Centrifugal governor
Charging system Flywheel alternator
PTO shaft rotation Counterclockwise (from PTO shaft side)

Cylinder Block and Head

Cylinder block
Compression ratio: 7.0:1
Cylinder bore: 82.55 mm (3.25 in)
Piston stroke: 66.55 mm (2.62 in)
Cylinder internal diameter (standard): 82.530-82.530 mm (3.2490-3.2500 in)
Number of piston rings (compression / oil): 2/1
Connecting rod big end diameter (standard): 41.360-41.350 mm (1.6283-1.6279 in)
Connecting rod small end diameter (standard): 17.470-17.480 mm (0.6878-0.6882 in)
Piston pin diameter: 17.470-17.480 mm (0.6878-0.6882 in)
Ring Groove Clearance (Top): 0.076-0.203 mm (0.003-0.008 in)
Ring End Gap in Cylinder Clearance: 0.254-0.508 mm (0.010-0.020 in)
Crankshaft Main Bearing Journal Diameter: 50.800-50.780 mm (2.0000-1.9992 in)
Crankpin journal diameter: 41.300-41.280 mm (1.6260-1.6252 in)
Crankshaft center distance: 33.275 mm (1.31 in)
Cylinder head
Valve arrangement: L-head, gear driven
Valves: 4,(2 valves in total)
Valve steam diameter (INTAKE): 7.099-7.112 mm (0.2795-0.2800 in)
Valve steam diameter (EXHAUST): 7.061-7.074 mm (0.278-0.2785 in)
Valve Clearance Stem-to-Guide (INTAKE): 0.025-0.064 mm (0.0010-0.0025 in)
Valve Clearance Stem-to-Guide (EXHAUST): 0.051-0.089 mm (0.0020-0.0035 in)
Valve spring free length (INTAKE): 40.64 mm (1.6 in)
Valve spring free length (EXHAUST): 40.64 mm (1.6 in)
Camshaft lobe height (INTAKE): 28.88 mm (1.137 in)
Camshaft lobe height (EXHAUST): 29.39 mm (1.1571 in)

Tightening Torque

Tightening torque specs
Gearcase cover 11-14 Nm (8-10 ft-lb)
Cylinder head bolts (asbestos gasket) 22-24 Nm (16-18 ft-lb)
Cylinder head bolts (graphoil gasket) 19-22 Nm (14-16 ft-lb)
Rear bearing plate screws 34-37 Nm (25-27 ft-lb)
Starter mounting bolts 33-35 Nm (24-26 ft-lb)
Connecting rod bolt 19 Nm (14 ft-lb)
Flywheel cap screw 67-75 Nm (50-55 ft-lb)
Other 1/4″ cylinder block stud and nuts 10-12 Nm (7-9 ft-lb)
Other 5/16″ cylinder block stud and nuts 11-14 Nm (8-10 ft-lb)
Oil base 24-31 Nm (18-23 ft-lb)
Intake manifold mounting screws 8-14 Nm (6-10 ft-lb)
Oil pump 10-12 Nm (7-9 ft-lb)
Valve cover 1-3 Nm (1-2 ft-lb)
Exhaust manifold mounting screws 12-15 Nm (9-11 ft-lb)

Service Data

Cylinder compression pressure: 517-793 kPa; 75-115 PSI
Valve clearance
Intake valve clearance: 0.13 mm (0.0051 in)
Exhaust valve clearance: 0.33 mm (0.0130 in)
Oil system
Lubrication system: Full pressure with oil filter
Oil type: API SF, SF/CC, or SF/CD
Recommended oil: SAE 5W-30, 10W-30, 30W, 40W
Oil capacity: Standard base (w/o oil filter): 1.4 L (1.5 US. qt, 1.2 Imp. qt.)
High capacity base (w/o oil filter): 2.6 L (2.75 US. qt, 2.3 Imp. qt.)
Oil filter: 0.3 L (0.32 US. qt, 0.26 Imp. qt.)
Fuel system
Type: Carburetor with fixed main jet
Pilot screw opening: 1-1/4 turns out
Fuel pump type: Pulse
Ignition system
Type: Electronic battery ignition system
Ignition timing: 20° B.T.D.C.
Spark plug: NGK: BPR5EFS; Champion: RS14YC
Spark plug gap: 0.64 mm (0.0252 in)

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