The Briggs and Stratton 253707 is a 399 cc (24.35 cu·in) natural aspirated single-cylinder four-stroke air-cooled internal combustion small gasoline engine, manufactured by Briggs & Stratton for general-purpose applications.
Cylinder bore is 87.3 mm (3.44 in) and 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 and 22.7 N·m (2.3 kg·m, 16.7 ft·lb) at 2,800 rpm of torque.
The Briggs and Stratton 253707 features:
- L-head (side valve) design
- Vertical PTO-shaft
- Transistor module ignition system
- Float type carburetor
- Centrifugal governor
- Forced air cooling system
- Electric starter
General information
| Engine Specifications | |
| Engine model | B&S 253707 |
| Engine type | 4-stroke, L-head (side valve), single-cylinder |
| Displacement | 399 cm3, (24.35 cu·in) |
| Max. horsepower | 11.2 PS (8.2 kW; 11.0 HP) at 3,600 rpm |
| Max. torque | 22.7 N·m (2.3 kg·m, 16.7 ft·lb) at 2,800 rpm |
| Cooling system | Forced air |
| Air cleaner | Dual element (cartridge and pre-cleaner) |
| Ignition system | Transistor module |
| Fuel system | Float type carburetor |
| Fuel used | Gasoline |
| Starting system | Electric starter |
| Governor | Centrifugal governor |
| PTO shaft rotation | Counterclockwise (from PTO shaft side) |
Cylinder Block and Head
| Cylinder block | |
| Compression ratio: | – |
| Cylinder bore: | 87.3 mm (3.44 in) |
| Piston stroke: | 66.7 mm (2.63 in) |
| Cylinder internal diameter (standard): | 87.290-87.310 mm (3.4366-3.4374 in) |
| Number of piston rings (compression / oil): | 2/1 |
| Connecting rod big end diameter (standard): | 31.760-31.810 mm (1.2504-1.2524 in) |
| Connecting rod small end diameter (standard): | 20.330-20.370 mm (0.8004-0.802 in) |
| Piston pin diameter: | 20.290-20.310 mm (0.7988-0.7996 in) |
| Ring end gap (Top): | 0.89 mm (0.035 in) |
| Ring end gap (Second): | 0.89 mm (0.035 in) |
| Ring end gap (Oil): | 1.14 mm (0.0449 in) |
| Crankshaft main journal diameter: | 35.000 mm (1.378 in) |
| Crankpin journal diameter: | 31.720 mm (1.2488 in) |
| Crankshaft center distance: | 33.35 mm (1.315 in) |
| Cylinder head | |
| Valve arrangement: | L-head (side valve) |
| Valves: | 2 |
Tightening torque
| 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 Data
| 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: | SE, SF or SG |
| Recommended oil: |
Summer: SAE 30, 10W-30 Winter: SAE 5W-20, 5W-30 |
| Oil capacity: | 1.4 L (1.48 US. qt, 1.23 Imp. qt.) |
| Fuel system | |
| Type: | Float type carburetor |
| Main Adjustment Screw | 1-1/2 turn out |
| Idle Adjustment Screw | 1 turn out turns out |
| Ignition system | |
| Type: | Transistor module |
| Spark plug: | Champion CJ-8, Champion RJ19LM |
| Spark plug gap: | 0.7-0.8 mm (0.0276-0.0315 in) |
| Spark plug torque: | 18 N·m (1.8 kg·m, 13.3 ft·lb) |
| Armature air gap | 0.25-0.36 mm (0.0098-0.0142 in) |
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