Briggs and Stratton 331877

Briggs and Stratton 331877The Briggs and Stratton 331877 Intek Plus Platinum is a 540 cc (32.9 cu·in) natural aspirated single-cylinder four-stroke air-cooled internal combustion small gasoline engine with a vertical shaft, manufactured by Briggs & Stratton for general-purpose applications.

Cylinder bore and piston stroke are 94.0 mm (3.7 in) and 77.8 mm (3.06 in), respectively. This engine produced 21.4 PS (15.7 KW; 21.0 HP) at 3,600 rpm of horsepower.

The Briggs and Stratton 331877 features:

  • OHV design
  • Cast iron sleeve
  • Electronic ignition system
  • Float type carburetor
  • Centrifugal governor
  • Full pressure lubrication system
  • Forced air cooling system
  • Electric starter 12V

General information

Engine Specifications
Engine model 331877 Intek Plus Platinum
Engine type 4-stroke, OHV, single-cylinder
Displacement 540 cm3, (32.9 cu·in)
Max. horsepower 21.4 PS (15.7 KW; 21.0 HP) at 3,600 rpm
Max. torque
Cooling system Forced air
Air cleaner Paper filter with a foam pre-cleaner
Lubricating system Full pressure
Ignition system Electronic ignition system
Fuel system Float type carburetor
Fuel used Gasoline
Starting system Electric starter 12V
Governor Centrifugal governor
Dimensions (L x W X H)
Dry weight

Cylinder Block and Head

Cylinder block
Cylinder bore: 94.0 mm (3.7 in)
Piston stroke: 77.8 mm (3.06 in)
Cylinder internal diameter (standard): 94.010-94.110 mm (3.7012-3.7051 in)
Number of piston rings (compression / oil): 2/1
Connecting rod big end diameter (standard): 27.940-27.990 mm (1.1-1.102 in)
Connecting rod small end diameter (standard): 15.890-15.920 mm (0.6256-0.6268 in)
Piston pin diameter: 15.850-15.890 mm (0.624-0.6256 in)
Side clearance (Top): 0.051-0.076 mm (0.002-0.003 in)
Side clearance (Second): 0.051-0.076 mm (0.002-0.003 in)
Side clearance (Oil): 0.051-0.076 mm (0.002-0.003 in)
Ring end gap (Top): 0.150-0.250 mm (0.0059-0.0098 in)
Ring end gap (Second): 0.300-0.510 mm (0.0118-0.0201 in)
Ring end gap (Oil): 0.510-0.630 mm (0.0201-0.0248 in)
Crankshaft main journal diameter: 41.240 mm (1.6236 in)
Crankpin journal diameter: 41.210-41.240 mm (1.6224-1.6236 in)
Crankshaft center distance: 38.9 mm (1.53 in)
Cylinder head
Valve arrangement: OHV, gear driven
Valves: 2
Valve steam diameter (INTAKE): 5.920-5.970 mm (0.2331-0.235 in)
Valve steam diameter (EXHAUST): 5.920-5.970 mm (0.2331-0.235 in)
Camshaft lobe height (INTAKE): 31.49 mm (1.2398 in)
Camshaft lobe height (EXHAUST): 31.49 mm (1.2398 in)
Camshaft journal diameter : 12.670 mm (0.4988 in)

Tightening torque specs

Tightening torque specs
Air cleaner base 6.0 Nm; 4.4 ft·lb
Alternator 2.0 Nm; 1.5 ft·lb
Armature 3.0 Nm; 2.2 ft·lb
Blower housings 10.0 Nm; 7.4 ft·lb
Breather 3.0 Nm; 2.2 ft·lb
Carburetor to intake manifold 8.0 Nm; 5.9 ft·lb
Carburetor solenoid 5.0 Nm; 3.7 ft·lb
Connecting rod 17.0 Nm; 12.6 ft·lb
Control bracket 5.0 Nm; 3.7 ft·lb
Crankcase sump 25.0 Nm; 18.5 ft·lb
Cylinder head 25.0 Nm; 18.5 ft·lb
Cylinder shield 5.0 Nm; 3.7 ft·lb
Exhaust manifold / adapter 19.0 Nm; 14.0 ft·lb
Flywheel nut 135.0 Nm; 100.0 ft·lb
Flywheel fan 16.0 Nm; 11.9 ft·lb
Fuel pump 10.0 Nm; 7.4 ft·lb
Governor lever nut 5.0 Nm; 3.7 ft·lb
Intake manifold to cylinder head 10.0 Nm; 7.4 ft·lb
Muffler 10.0 Nm; 7.4 ft·lb
Oil drain plug 11.0 Nm; 8.1 ft·lb
Oil fill tube 10.0 Nm; 7.4 ft·lb
Oil pump cover 10.0 Nm; 7.4 ft·lb
Regulator / Rectifier 5.0 Nm; 3.7 ft·lb
Rewind starter 3.0 Nm; 2.2 ft·lb
Rocker ball set screw or nut 5.0 Nm; 3.7 ft·lb
Rocker cover 7.0 Nm; 5.2 ft·lb
Starter motor 16.0 Nm; 11.9 ft·lb

Service Data

Valve clearance
Intake valve clearance: 0.08-0.13 mm (0.0031-0.0051 in)
Exhaust valve clearance: 0.13-0.18 mm (0.0051-0.0071 in)
Oil system
Lubrication system: Full pressure
Oil type: SF, SG, SH, SJ or higher
Recommended oil: Summer: SAE 30, 10W-30
Winter: SAE 5W-30
Oil capacity: 1.40 L (1.48 US. qt, 1.23 Imp. qt.)
Fuel system
Type Float type carburetor
Fuel pump Pulse type
Ignition system
Type: Electronic ignition system
Spark plug: Champion RC12YC
Spark plug gap: 0.7-0.8 mm (0.0276-0.0315 in)
Spark plug torque: 20 N·m (2 kg·m, 14.7 ft·lb)
Armature air gap 0.25-0.36 mm (0.0098-0.0142 in)

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