Briggs and Stratton 31Q777 Specs
| Engine Model: Briggs and Stratton 31Q777 |
| Engine Type: 4-cycle 1-cylinder overhead valve air-cooled gasoline |
| Total Displacement: 30.5 cu.in (500 cc) |
| Rated Engine Power: 18.5 Hp (13.7 kW) at 3300 rpm |
| Fuel System Type: Float carburetor |
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Engine Model ................ Briggs and Stratton 31Q777
Engine Type ................ 4-cycle single cylinder OHV vertical shaft air-cooled gasoline engine
Number of Cylinders ................ 1
Displacement, cu.in (cc) ................ 30.5 (500)
Cylinder Bore, in (mm) ................ 3.56 (91.0)
Piston Stroke, in (mm) ................ 3.06 (78.0)
Rated Engine Power, hp (kW) ................ 18.5 (13.7)
Rated Engine Speed, rpm ................ 3300
Idle Speed, rpm ................ 1750
Cylinder Bore Type ................ Cast iron sleeve
Lubrication System ................ Oil pump with filter
Air Cleaner ................ Dual element
Cooling System ................ Forced air
Ignition System ................ Magnetron electronic
Starting System ................ Electric starter
Electrical System Rating, Volts ................ 12
Fuel System Type ................ Carburetor
Carburetor Type ................ Float
Fuel Pump ................ Pulse type
Governor Type ................ Mechanical
Fuel Type ................ Gasoline
Overall Length, in (mm) ................ 19.1 (482)
Overall Width, in (mm) ................ 16.1 (407)
Overall Height, in (mm) ................ 12.5 (316)
Net Weight, lbs (kg) ................ 90.0 (40.9)
Cylinder Bore I.D. (Standard), in (mm) ................ 3.563 (90.50)
Cylinder Bore I.D. (Maximum), in (mm) ................ 3.567 (90.60)
Cylinder Bore (Out-Of-Round), in (mm) ................ 0.0015 (0.04)
Main Bearing Bore Dia. (Cylinder Block), in (mm) ................ 1.3795 (35.04)
Main Bearing Bore Dia. (Crankcase Cover), in (mm) ................ 1.063 (27.00)
Camshaft Bearing Bore Dia. (Cylinder Block), in (mm) ................ 0.5011 (15.88)
Camshaft Bearing Bore Dia. (Crankcase Cover), in (mm) ................ 0.501 (12.72)
Crank Pin Journal O.D. (Standard), in (mm) ................ 1.4982 (38.05)
Crank Pin Journal O.D. (Wear Limit), in (mm) ................ 1.497 (31.02)
Crankshaft Journal O.D. (Magneto Side), in (mm) ................ 1.3775 (35.00)
Crankshaft Journal O.D. (PTO Side), in (mm) ................ 1.3775 (35.00)
Crankshaft Eccentrics (Standard), in (mm) ................ 2.2045 (55.91)
Crankshaft Eccentrics (Wear Limit), in (mm) ................ 2.202 (55.93)
Crankshaft End Play, in (mm) ................ 0.002-0.023 (0.05-0.58)
Camshaft Journal O.D. (Magneto Side), in (mm) ................ 0.499 (12.67)
Camshaft Journal O.D. (PTO Side), in (mm) ................ 0.499 (12.67)
Connecting Rod Big End I.D. (Standard), in (mm) ................ 1.2505 (31.76)
Connecting Rod Big End I.D. (Wear Limit), in (mm) ................ 1.2525 (31.81)
Connecting Rod Small End I.D. (Standard), in (mm) ................ 0.8006 (20.33)
Connecting Rod Small End I.D. (Wear Limit), in (mm) ................ 0.802 (20.37)
Counterweight Bearings Dia. (Standard), in (mm) ................ 2.207 (56.05)
Counterweight Bearings Dia. (Wear Limit), in (mm) ................ 2.210 (56.13)
Cylinder Head (Max Out of Flatness), in (mm) ................ 0.004 (0.10)
Intake Valve Clearance, in (mm) ................ 0.003-0.005 (0.08-0.13)
Exhaust Valve Clearance, in (mm) ................ 0.005-0.007 (0.13-0.18)
Valve Guide I.D. (Standard), in (mm) ................ 0.237 (6.02)
Valve Guide I.D. (Wear Limit), in (mm) ................ 0.240 (6.10)
Intake Valve Stem O.D. (Standard), in (mm) ................ 0.235 (5.97)
Intake Valve Stem O.D. (Wear Limit), in (mm) ................ 0.233 (5.92)
Exhaust Valve Stem O.D. (Standard), in (mm) ................ 0.235 (5.97)
Exhaust Valve Stem O.D. (Wear Limit), in (mm) ................ 0.233 (5.92)
Cam Lobes (Intake), in (mm) ................ 1.240 (31.49)
Cam Lobes (Exhaust), in (mm) ................ 1.240 (31.49)
Piston Pin O.D. (Standard), in (mm) ................ 0.7998 (20.31)
Piston Pin O.D. (Wear Limit), in (mm) ................ 0.799 (20.29)
Piston Pin Bearing I.D. (Standard), in (mm) ................ 0.8006 (20.33)
Piston Pin Bearing I.D. (Wear Limit), in (mm) ................ 0.802 (20.37)
Top Ring End Gap (Standard), in (mm) ................ 0.006-0.009 (0.15-0.23)
Second Ring End Gap (Standard), in (mm) ................ 0.014-0.018 (0.35-0.45)
Oil Ring End Gap (Standard), in (mm) ................ 0.006-0.010 (0.15-0.25)
Piston Ring End Gap (Wear Limit), in (mm) ................ 0.030 (0.76)
Top Ring Side Clearance (Standard), in (mm) ................ 0.002-0.005 (0.05-0.12)
Second Ring Side Clearance (Standard), in (mm) ................ 0.002-0.005 (0.05-0.12)
Oil Ring Side Clearance (Standard), in (mm) ................ 0.002-0.005 (0.05-0.12)
Piston Ring Side Clearance (Wear Limit) ................ 0.007 (0.18)
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)
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)
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 ................ 696854
Air Filter Element Part Number ................ 793569
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
Air Filter (Cartridge). Part Number ................ 793569
Air Filter (Pre-Cleaner). Part Number ................ 793685
Oil Filter. Part Number ................ 696854, 492932S
Fuel Filter. Part Number ................ 394358S, 84001895
Spark Plug. Part Number ................ 792015, 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
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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