Briggs and Stratton 253707 (11.0 HP, 399 cc) engine: review and specs

The Briggs and Stratton 253707 is a 399 cc (24.3 cu·in) single-cylinder air-cooled four-stroke internal combustion gasoline engine, manufactured by Briggs and Stratton.

The B&S 253707 engine has an L-head (side valve) design and a vertical PTO shaft. This engine is equipped with float type carburetor and an transistor module ignition system. The B&S 253707 engine used a dual element air cleaner: cartridge and pre-cleaner.

The cylinder bore is 87.30 mm (3.44 in) and the piston stroke is 66.7 mm (2.63 in). This engine produced 11.2 PS (8.2 kW; 11.0 HP) at 3,600 rpm of horsepower.

The breakdown of the engine code is as follows:

25 – Displacement
3 – Basic design series
7 – Vertical PTO-shaft
0 – Plain bearing
7 – Electric starter

General information

Engine Specifications
Model	B&S 253707
Type	4-stroke, L-head, single-cylinder
Displacement	399 cm ³ (24.3 cu-in)
Max. horsepower	11.2 PS (8.2 kW; 11 HP) at 3,600 rpm
Max. torque	22.7 N·m (2.3 kg·m, 16.7 ft·lb) at 2,800 rpm
Fuel system	Carburetor
Cooling system	Forced-air
Ignition system	Transistor module
Lubricating system	Splash type
Starting system	Electric starter
Fuel used	Unleaded gasoline (octane number 86 or higher)
Fuel tank capacity	–

Cylinder Block and Head

Cylinder block
Compression ratio:		–
Bore x Stroke		87.3 mm X 66.7 mm (3.44 x 2.63 in)
Sleeve internal diameter		87.290-87.310 mm (3.4366-3.4374 in)
Number of piston rings (compression / oil):		2 / 1
Ring end gap	Compression ring	0.89 mm (0.035 in)
	Oil ring	1.14 mm (0.0449 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

Tightening torque specs

Tightening torque specs
Cylinder Head	18.6 Nm; 13.8 ft·lb
Connecting Rod	20.9 Nm; 15.5 ft·lb
Flywheel Nut	87.8 Nm; 65.0 ft·lb
Crankcase Cover	15.8 Nm; 11.7 ft·lb
Fuel Shut-Off Valve	8.0 Nm; 5.9 ft·lb
Governor Lever Nut	7.0 Nm; 5.2 ft·lb
Spark Plug Torque	18.0 Nm; 13.5 ft·lb
Oil Drain Plug	20.0 Nm; 14.9 ft·lb

Service Information

Engine
Max speed	3,600 rpm
Valve clearance
Intake valve clearance	0.08-0.13 mm (0.003-0.005 in)
Exhaust valve clearance	0.13-0.15 mm (0.005-0.006 in)
Oil system
Oil type	API SE, SF or SG
Recommended oil	Summer: SAE 30, 10W-30 Winter: SAE 5W-20, 5W-30
Oil capacity (with filter)	1.4 L (1.48 US. qt, 1.23 Imp. qt.)
Ignition system
Spark plug	Champion: CJ-8 or 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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