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Honda G-50 Engine

General Technical Data

Honda G50 Engine Specifications

Engine Model ................. Honda G50
Engine Type ................. 4-cycle single-cylinder air-cooled horizontal shaft small gasoline engine
Number of Cylinders ................. 1
Displacement, cu.in (cc) ................. 11.41 (187)
Engine Bore, in (mm) ................. 2.72 (69.0)
Engine Stroke, in (mm) ................. 1.97 (50.0)
Rated Engine Power, hp (kW) ................. 4.9 (3.65)
Rated Engine Speed, rpm ................. 4000
Maximum Torque, Nm (ft-lbs) ................. 9.0 (6.6)
Torque Speed, rpm ................. 3600
Compression ................. 6.5:1
PTO Shaft Rotation ................. Counterclockwise (from PTO shaft side)
Valve Arrangement ................. L-head
Lubrication System ................. Splash type
Air Cleaner ................. Oil bath
Cooling System ................. Forced air
Ignition System ................. High voltage
Starter Type ................. Recoil

Fuel System

Fuel System Type ................. Carburetor
Carburetor Type ................. Horizontal with butterfly valve
Governor Type ................. Centrifugal
Fuel Tank Capacity, qts (L) ................. 3.6 (3.4)
Fuel Type ................. Gasoline (86 or higher)

Honda G50 Maintenance Data

Cylinder Block and Valves

Cylinder Bore Inside Diameter (Maximum), in (mm) ................. 2.722 (69.055)
Cylinder Head (Max. Out of Flatness), in (mm) ................. 0.002 (0.05)
Intake Valve Clearance, in (mm) ................. 0.0028 (0.007)
Exhaust Valve Clearance, in (mm) ................. 0.0028 (0.007)

Engine Oil

Engine Oil Type (Summer) ................. SAE 10W-40
Engine Oil Type (Winter) ................. SAE 10W
API Service Classifications ................. SD or MS
Oil Capacity, qts (L) ................. 0.64 (0.60)

Ignition System

Spark Plug Type ................. NGK B6HS
Spark Plug Gap, in (mm) ................. 0.0236-0.0276 (0.60-0.70)
Thread Size, in (mm) ................. 0.47 (12.0)
Ignition Timing, deg ................. 20 BTDC

Service Intervals

Service Air Cleaner ................. Every 50 hours
Change Engine Oil ................. Every 50 hours
Clean Fuel Strainer ................. Every 100 hours
Check and Service Spark Plug ................. Every 100 hours
Check Drive Belt ................. Every 100 hours
Check Ignition Timing ................. Every 200 hours
Replace Spark Plug ................. Every 300 hours
Check and Adjust Valve Clearance ................. Every 300 hours

Honda G50 Service Specifications

Cylinder Block

Cylinder Compression, psi (kPa) ................. 100.0 (690)
Cylinder Bore Inside Diameter (Std), in (mm) ................. 2.7165 (69.00)
Cylinder Bore Inside Diameter (Wear Limit), in (mm) ................. 2.722 (69.055)
Piston Skirt Outside Diameter, in (mm) ................. 2.7153-2.7161 (68.97-68.99)
Connecting Rod Small End Diameter (Std), in (mm) ................. 0.7091-0.7098 (18.01-18.03)
Top Compression Ring to Groove Side Clearance, in (mm) ................. 0.0008-0.0024 (0.02-0.06)
Second Compression Ring to Groove Side Clearance, in (mm) ................. 0.0008-0.0024 (0.02-0.06)
Oil Ring to Groove Side Clearance, in (mm) ................. 0.0008-0.0024 (0.02-0.06)
Top Compression Ring End Gap, in (mm) ................. 0.0079-0.0157 (0.20-0.40)
Second Compression Ring End Gap, in (mm) ................. 0.0079-0.0157 (0.20-0.40)
Oil Ring End Gap, in (mm) ................. 0.0079-0.0157 (0.20-0.40)

Cylinder Head and Valves

Number of Valves ................. 2
Cylinder Head (Max. Out of Flatness), in (mm) ................. 0.002 (0.05)
Intake Valve Clearance, in (mm) ................. 0.0028 (0.007)
Exhaust Valve Clearance, in (mm) ................. 0.0028 (0.007)
Intake Valve Stem Diameter, in (mm) ................. 0.2744 (6.97)
Exhaust Valve Stem Diameter, in (mm) ................. 0.2726 (6.925)
Valve Spring Free Length, in (mm) ................. 1.0984 (27.90)
Camshaft Journal Diameter, in (mm) ................. 0.4711-0.4718 (11.966-11.984)