________________________________________________________________________________________

Home / Engines / Briggs and Stratton Engines / Briggs and Stratton 31R777

Briggs and Stratton 31R777 Specs

The Briggs and Stratton 31R777 is a 501 cc (30.6 cubic inches) single-cylinder air-cooled 4-cycle internal combustion gasoline engine, manufactured by Briggs and Stratton. The Briggs 31R777 engine has an OHV (overhead) design and a vertical PTO shaft. This engine is equipped with float type carburetor and an electronic ignition system. The engine used a dual element air filter. It is equipped with an electric starter (12V). The cylinder bore is 90.6 mm (3.57 in) and the piston stroke is 77.8 mm (3.06 in). This engine output 15.6 PS (11.5 KW; 15.5 HP) at 3,600 rpm of maximum power. Engine code identification: 31 - Total displacement, R - Basic design series, 7 - Vertical PTO-shaft, 7 - Plain bearing, Pressure lubrication, 7 - Electric starter.

General Technical Data

Engine Model ................ Briggs and Stratton 31R777 Intek
Engine Type ................ 4-cycle single cylinder OHV vertical shaft air-cooled gasoline engine
Number of Cylinders ................ 1
Displacement, cu.in (cc) ................ 30.59 (501)
Cylinder Bore, in (mm) ................ 3.56 (91.0)
Piston Stroke, in (mm) ................ 3.06 (78.0)
Rated Engine Power, hp (kW) ................ 15.5 (11.5)
Rated Engine Speed, rpm ................ 3600
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 ................ Electronic
Starting System ................ Electric starter
Electrical System Rating, Volts ................ 12
Charging System Rating, Amps ................ 9

Fuel System

Fuel System Type ................ Carburetor
Carburetor Type ................ Float
Governor Type ................ Mechanical
Fuel Type ................ Gasoline

Cylinder Block

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 and Valves

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 and Piston Rings

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)

________________________________________________________________________________________

________________________________________________________________________________________

Engines Technical Specifications
BRIGGS 28S777 BRIGGS 31H777 BRIGGS 31P977 BRIGGS 31Q777
HONDA GC135 HONDA GCV160 HONDA GS190 HONDA GX340
KOHLER CH18S KOHLER CH680 KOHLER CV460S KOHLER SV735S
KUBOTA D1305 KUBOTA D1503 KUBOTA V1903 KUBOTA 2003T
MERCURY 150 MERCURY 175 XRI MARINER 135 MERCURY 200 EFI
KAWASAKI FH430V KAWASAKI FR600V KAWASAKI FX541V KAWASAKI FD611V
BMW M20B23 BMW M40B18 BMW M43B16 BMW M50B24TU
TOYOTA 3VZ-E TOYOTA 1AZ-FE TOYOTA 1G-FE TOYOTA 1JZ-GE
NISSAN HR12DE NISSAN A12 NISSAN A15 NISSAN CA18DET