Briggs and Stratton 254425

Briggs and Stratton 254425The Briggs and Stratton 254425 is a 399 cc (24.3 cu·in) single-cylinder, air-cooled, four-stroke cycle, internal combustion gasoline engine with horizontal PTO-shaft, manufactured by Briggs and Stratton.

The Briggs and Stratton 254425 engine has a L-head (side valve) design and a horizontal PTO shaft. The Briggs and Stratton 254425 engine is equipped with flo-jet type carburetor, an transistor module ignition system, splash type lubrication system and 12V electric starter.

A 87.30 mm (3.44 in) cylinder bore and 66.7 mm (2.63 in) piston stroke give this engine a total 399 cc (24.3 cu·in) of displacement. The B&S 254425 engine produced 11.2 PS (8.2 kW; 11.0 HP) at 3,600 rpm of maximum horsepower.

The breakdown of the engine code is as follows:

  • 25 – Displacement
  • 4 – Basic design series
  • 4 – Horizontal PTO-shaft, Flo-jet carburetor
  • 2 – Sleeve bearing, flange mounting
  • 5 – Electric starter 12V, gear drive

General information

Engine Specifications
ModelB&S 254425
Type4-stroke, L-head, single-cylinder
Displacement399 cm 3 (24.3 cu-in)
Max. horsepower11.2 PS (8.2 kW; 11.0 HP) at 3,600 rpm
Max. torque
Fuel systemFlo-jet carburetor
Cooling systemForced-air
Ignition systemTransistor module
Lubrication systemSplash type
Starting systemElectric starter 12V
Fuel usedUnleaded gasoline (octane number 86 or higher)
Fuel tank capacity

Cylinder Block and Head

Cylinder block
Compression ratio:
Bore x Stroke87.3 mm X 66.7 mm (3.44 x 2.63 in)
Sleeve internal diameter87.290-87.310 mm (3.4366-3.4374 in)
Number of piston rings (compression / oil):2 / 1
Ring groove clearance0.228 mm (0.009 in)
Ring end gap (compression ring)0.890 mm (0.035 in)
Ring end gap (oil ring)1.140 mm (0.045 in)
Piston pin outer diameter20.290 mm (0.799 in)
Pin bore inner diameter20.350 mm (0.801 in)
Connecting rod small end bearing20.370 mm (0.802 in)
Connecting rod big end bearing31.800 mm (1.252 in)
Crankshaft main journal diameter PTO side: 34.950 mm (1.376 in)
Magneto side: 34.950 mm (1.376 in)
Crankpin diameter31.670 mm (1.2469 in)
Cylinder Head
Valve Arrangement:L-head (sidevalve)
Valves:2
Cam gear journal diameter:12.650 mm (0.498 in)
Cam lobe:30.070 mm (1.1839 in)

Tightening torque specs

Tightening torque specs
Cylinder Head19.0 Nm (1.9 kgf·m; 14 ft·lb)
Connecting Rod21.0 Nm (2.1 kgf·m; 15.5 ft·lb)
Flywheel Nut87.8 Nm (9 kgf·m; 64.8 ft·lb)
Crankcase Cover16.0 Nm (1.6 kgf·m; 11.8 ft·lb)
Fuel Shut-Off Valve8.0 Nm (0.8 kgf·m; 5.9 ft·lb)
Governor Lever Nut7.0 Nm (0.7 kgf·m; 5.2 ft·lb)
Spark Plug Torque18.0 Nm (1.8 kgf·m; 13.3 ft·lb)
Oil Drain Plug20.0 Nm (2 kgf·m; 14.8 ft·lb)

Service Information

Engine
Max speed3,600 rpm
Valve clearance
Intake valve clearance0.13-0.18 mm (0.005-0.007 in)
Exhaust valve clearance0.23-0.28 mm (0.009-0.011 in)
Oil system
Oil typeAPI SF, SG, SH, SJ or higher
Recommended oil Summer: SAE 30, 10W-30
Winter: SAE 5W-20, 5W-30
Oil capacity (with filter)1.4 liters (1.5 US.qts, 1.24 Imp. qts)
Ignition system
Spark plugChampion CJ-8
Spark plug gap0.762 mm (0.030 in)
Ignition armature air gap0.254-0.356 mm (0.010-0.014 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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