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| Home / Engines / Briggs and Stratton Engines / Briggs and Stratton 31P977 |
Briggs Stratton 31P977 Maintenance
| Engine Model: Briggs and Stratton 31P977 |
| Engine Type: 4-cycle single cylinder OHV vertical shaft gasoline engine |
| Total Displacement: 30.6 cu.in (501 cc) |
| Rated Engine Power: 20 Hp (14.9 kW) at 3600 rpm |
| Fuel System: Float type carburetor with fixed main jet |
| Service Data |
Cylinder Bore Inside Diameter (Maximum), in (mm) ................ 3.567 (90.60)
Cylinder Head (Max Out of Flatness), in (mm) ................ 0.004 (0.10)
Valve Clearance (Intake), in (mm) ................ 0.003-0.005 (0.08-0.13)
Valve Clearance (Exhaust), in (mm) ................ 0.005-0.007 (0.13-0.18)
| Engine Oil and Filters |
Engine Oil Type (Summer) ................ SAE 30, 10W-30
Engine Oil Type (Winter) ................ SAE 5W-30
API Service Classifications ................ SF, SG, SH, SJ or higher
Oil Capacity, qts (L) ................ 1.51 (1.42)
Oil Filter Part Number ................ 492932S
Air Filter Element Part Number ................ 697153
| Ignition System |
Spark Plug Type ................ Champion RC12YC
Spark Plug Gap, in (mm) ................ 0.03 (0.76)
Armature Air Gap, in (mm) ................ 0.010-0.014 (0.25-0.36)
Spark Plug Torque, Nm (lb-ft) ................ 20 (14.8)
| Service Intervals |
Check Engine Oil Level ................ Every 10 hours
Service Air Filter Pre-Cleaner ................ Every 25 hours
Clean Air Filter Cartridge ................ Every 25 hours
Change Engine Oil ................ Every 50 hours
Check and Adjust Spark Plug ................ Every 50 hours
Replace Engine Oil Filter ................ Every 100 hours
Replace Fuel Filter ................ Every 100 hours
Replace Spark Plug ................ Every 100 hours
Replace Air Filter Pre-Cleaner ................ Every 100 hours
Replace Air Filter Cartridge ................ Every 100 hours
Clean Combustion Chamber ................ Every 200 hours
Check Carburetor Adjustment ................ Every 200 hours
Check and Adjust Idle Speed ................ Every 200 hours
Check and Adjust Valve Clearance ................ Every 200 hours
| Replacement Parts |
Air Filter (Cartridge). Part Number ................ 697153, 698083
Air Filter (Pre-Cleaner). Part Number ................ 697015
Oil Filter. Part Number ................ 795890, 492932S
Fuel Filter. Part Number ................ 394358S
Spark Plug. Part Number ................ 691043, 491055S
Crankshaft Oil Seal (Mag). Part Number ................ 391086S
Crankshaft Oil Seal (PTO). Part Number ................ 795387
Cylinder Head Gasket. Part Number ................ 796584
Crankcase Gasket. Part Number ................ 697110
| Tightening Torques |
Air Cleaner Base, lb-ft (Nm) ................ 4.4 (6.0)
Alternator, lb-ft (Nm) ................ 1.5 (2.0)
Armature, lb-ft (Nm) ................ 2.2 (3.0)
Blower Housings, lb-ft (Nm) ................ 7.4 (10.0)
Blower Housing Brackets, lb-ft (Nm) ................ 7.4 (10.0)
Breather, lb-ft (Nm) ................ 2.2 (3.0)
Carburetor to Intake Manifold, lb-ft (Nm) ................ 5.9 (8.0)
Carburetor Solenoid, lb-ft (Nm) ................ 3.7 (5.0)
Connecting Rod, lb-ft (Nm) ................ 12.6 (17.0)
Control Bracket, lb-ft (Nm) ................ 2.2 (3.0)
Crankcase Sump, lb-ft (Nm) ................ 18.5 (25.0)
Cylinder Head, lb-ft (Nm) ................ 18.5 (25.0)
Cylinder Shield, lb-ft (Nm) ................ 3.7 (5.0)
Exhaust Manifold/Adapter, lb-ft (Nm) ................ 14.1 (19.0)
Flywheel Nut, lb-ft (Nm) ................ 100.0 (135.0)
Flywheel Fan, lb-ft (Nm) ................ 11.9 (16.0)
Fuel Pump, lb-ft (Nm) ................ 7.4 (10.0)
Governor Lever Nut, lb-ft (Nm) ................ 3.7 (5.0)
Intake Manifold to Cylinder Head, lb-ft (Nm) ................ 7.4 (10.0)
Muffler, lb-ft (Nm) ................ 7.4 (10.0)
Oil Drain Plug, lb-ft (Nm) ................ 8.1 (11.0)
Oil Fill Tube, lb-ft (Nm) ................ 7.4 (10.0)
Oil Pump Cover, lb-ft (Nm) ................ 7.4 (10.0)
Regulator/Rectifier, lb-ft (Nm) ................ 3.7 (5.0)
Rewind Starter, lb-ft (Nm) ................ 2.2 (3.0)
Rocker Ball Set Screw or Nut, lb-ft (Nm) ................ 3.7 (5.0)
Spark Plug, lb-ft (Nm) ................ 14.8 (20.0)
Starter Motor, lb-ft (Nm) ................ 11.9 (16.0)
Rocker Cover, lb-ft (Nm) ................ 5.2 (7.0)
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