The Briggs and Stratton 28R777 is a 465 cc (28.4 cu·in) single-cylinder air-cooled four-stroke internal combustion gasoline engine, manufactured by Briggs and Stratton.
The B&S 28R707 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 28R707 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 13.6 PS (10.0 kW; 13.5 HP) at 3,300 rpm of horsepower.
The breakdown of the engine code is as follows:
- 28 – Displacement
- R – Basic design series
- 7 – Vertical PTO-shaft
- 0 – Plain bearing
- 7 – Electric starter
General information
| Engine Specifications | |
| Model | B&S 28R707 |
| Type | 4-stroke, L-head, single-cylinder |
| Displacement | 465 cm 3 (28.38 cu-in) |
| Max. horsepower | 13.6 PS (10.0 kW; 13.5 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
| Engine | |
| Max speed | 3,600 rpm |
| Valve clearance | |
| Intake valve clearance | 0.08-0.13 mm (0.003-0.005 in) |
| Exhaust valve clearance | 0.13-0.18 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) |
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