Briggs and Stratton 28M707

Briggs and Stratton 28M707The Briggs and Stratton 28M707 is a 465 cc (28.38 cu·in) single-cylinder air-cooled four-stroke internal combustion gasoline engine, manufactured by Briggs and Stratton.

The B&S 28M707 engine has an L-head (side valve) design and a vertical PTO shaft. This engine is equipped with float type carburetor and an electronic ignition system. The B&S 28M707 engine used a paper air filter with a foam pre-cleaner.

The cylinder bore is 87.30 mm (3.44 in) and the piston stroke is 77.7 mm (3.06 in). This engine produced 13.1 PS (9.6 kW; 13.0 HP) at 3,300 rpm of horsepower.

The breakdown of the engine code is as follows:

  • 28 – Displacement
  • M – Basic design series
  • 7 – Vertical PTO-shaft
  • 0 – Plain bearing
  • 7 – Electric starter

General information

Engine Specifications
Model B&S 28M707
Type 4-stroke, L-head, single-cylinder
Displacement 465 cm 3 (28.38 cu-in)
Max. horsepower 13.1 PS (9.6 kW; 13.0 HP) at 3,300 rpm
Max. torque
Fuel system Carburetor
Cooling system Forced-air
Ignition system Electronic
Lubricating system
Starting system Electric starter
Fuel used Gasoline
Fuel tank capacity

Cylinder Block and Head

Cylinder block
Compression ratio:
Bore x Stroke 87.3 mm X 77.7 mm (3.44 x 3.06 in)
Sleeve internal diameter 87.300-87.400 mm (3.437-3.4409 in)
Number of piston rings (compression / oil): 2 / 1
Side clearance Top 0.03-0.07 mm (0.0012-0.0028 in)
Second 0.03-0.07 mm (0.0012-0.0028 in)
Oil 0.03-0.07 mm (0.0012-0.0028 in)
Ring end gap Top 0.15-0.35 mm (0.0059-0.0138 in)
Second 0.15-0.35 mm (0.0059-0.0138 in)
Oil 0.35-0.70 mm (0.0138-0.0276 in)
Connecting rod small end ID 20.330-20.370 mm (0.8004-0.802 in)
Piston pin outer diameter 20.290-20.310 mm (0.7988-0.7996 in)
Cylinder Head
Valve Arrangement: L-head (sidevalve)
Valves: 2
Valve steam diameter INTAKE 5.960-5.980 mm (0.235-0.235 in)
EXHAUST 5.960-5.980 mm (0.235-0.235 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
Blower housing brackets 10.0 Nm; 7.4 ft·lb
Breather 4.0 Nm; 2.9 ft·lb
Carburetor to intake manifold 7.0 Nm; 5.2 ft·lb
Connecting rod 21.0 Nm; 15.6 ft·lb
Control bracket 5.0 Nm; 3.7 ft·lb
Crankcase cover 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 5.0 Nm; 3.7 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 19.0 Nm; 14.1 ft·lb
Oil drain plug 14.0 Nm; 10.4 ft·lb
Oil pump cover 10.0 Nm; 7.4 ft·lb
Starter motor 16.0 Nm; 11.9 ft·lb

Service Information

Max speed 3,600 rpm
Valve clearance
Intake valve clearance 0.08-0.13 mm (0.003-0.005 in)
Exhaust valve clearance 0.13-0.18 mm (0.005-0.007 in)
Oil system
Oil type API SF, SG, SH, SJ or higher
Recommended oil Summer: SAE 30, 10W-30
Winter: SAE 5W-30
Oil capacity (with filter) 1.40 L (1.48 US. qt, 1.23 Imp. qt.)
Ignition system
Spark plug Champion RJ19LM
Spark plug gap 0.7-0.8 mm (0.0276-0.0315 in)
Author: Sergei Wers
About: Co-founder and CEO of a multi-brand auto repair shop (engine repair, chassis repair, body repair and painting) for over 15 years. I have been developing internet sites with technical specifications for more than seven years.

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