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Honda GX-100 Engine

General Technical Data

Honda GX100 Engine Specifications

Engine Model ................. Honda GX100
Engine Type ................. 4-cycle overhead camshaft 1-cylinder air-cooled small gasoline engine
Number of Cylinders ................. Single
Displacement, cu.in (cc) ................. 6.0 (98)
Engine Bore, in (mm) ................. 2.21 (56.0)
Engine Stroke, in (mm) ................. 1.59 (40.0)
Rated Engine Power, hp (kW) ................. 3.0 (2.3)
Rated Engine Speed, rpm ................. 4000
Maximum Torque, Nm (ft-lbs) ................. 5.7 (4.2)
Torque Speed, rpm ................. 3600
Compression ................. 8.5:1
PTO Shaft Rotation ................. Counterclockwise (from PTO side)
Valve Arrangement ................. OHC
Lubrication System ................. Splash type
Air Cleaner ................. Dual element
Cooling System ................. Forced air
Ignition System ................. Transistorized magneto
Stopping System ................. Primary circuit ground
Starting System ................. Recoil starter

Fuel System

Fuel System Type ................. Carburetor
Carburetor Type ................. Horizonal, butterfly valve
Governor Type ................. Centrifugal mechanical
Fuel Tank Capacity, qts (L) ................. 1.3 (1.2)
Fuel Type ................. Gasoline (86 or higher)

Dimensions and Weight

Length, in (mm) ................. 11.6 (295)
Width, in (mm) ................. 12.0 (304)
Height, in (mm) ................. 15.8 (402)
Net Weight, lbs (kg) ................. 23.4 (10.6)

Honda GX100 Maintenance Data

Cylinder Block and Valves

Cylinder Bore Inside Diameter (Maximum), in (mm) ................. 2.2112 (56.165)
Cylinder Compression, psi (kPa) ................. 71 (490)
Cylinder Head (Max. Out of Flatness), in (mm) ................. 0.004 (0.10)
Intake Valve Clearance, in (mm) ................. 0.006 (0.15)
Exhaust Valve Clearance, in (mm) ................. 0.008 (0.20)

Engine Oil and Filter

Engine Oil Type (Summer) ................. SAE30, SAE 10W-30
Engine Oil Type (Winter) ................. SAE 5W-30
API Service Classifications ................. SJ or higher
Oil Capacity, qts (L) ................. 0.42 (0.40)
Air Filter Element Part Number ................. 17231-Z0D-000

Carburetor Adjustment

Main Jet ................. #60
Pilot Jet ................. #35
Idle Fuel ................. 2-3/8 turns out
Float Height, in (mm) ................. 0.50 (12.0)
Low Idle Speed, rpm ................. 1550±150
High Idle Speed, rpm ................. 4000±150

Ignition System

Spark Plug Type ................. NGK CR5HSB or Denso U16FSR
Spark Plug Gap, in (mm) ................. 0.024-0.028 (0.60-0.70)
Module Air Gap, in (mm) ................. 0.008-0.020 (0.20-0.50)
Ignition Timing, deg ................. 25 BTDC
Spark Plug Torque, Nm (ft-lbs) ................. 12 (9)

Service Intervals

Clean Air Cleaner Element ................. Every 50 hours
Change Engine Oil ................. Every 100 hours
Check and Adjust Spark Plug ................. Every 100 hours
Check Carburetor Adjustment ................. Every 100 hours
Check and Adjust Valve Clearance ................. Every 200 hours
Replace Air Cleaner Element ................. Every 200 hours
Replace Spark Plug ................. Every 200 hours

Honda GX100 Service Specifications

Cylinder Block

Cylinder Bore Inside Diameter (Std), in (mm) ................. 2.2047-2.2053 (56.000-56.015)
Cylinder Bore Inside Diameter (Wear Limit), in (mm) ................. 2.2112 (56.165)
Connecting Rod Small End Inside Diameter (Std), in (mm) ................. 0.5120-0.5126 (13.005-13.020)
Connecting Rod Small End Inside Diameter (Wear Limit), in (mm) ................. 0.515 (13.07)
Connecting Rod Big End Inside Diameter (Std), in (mm) ................. 0.9449-0.9454 (24.000-24.013)
Connecting Rod Big End Inside Diameter (Wear Limit), in (mm) ................. 0.9465 (24.040)
Connecting Rod Big End Oil Clearance, in (mm) ................. 0.0008-0.0017 (0.020-0.043)
Crank Pin Outside Diameter, in (mm) ................. 0.9437-0.9441 (23.970-23.980)
Cam Height, in (mm) ................. 1.4363 (36.483)
Rocker Arm Inside Diameter (Std), in (mm) ................. 0.2362-0.2369 (6.000-6.018)
Rocker Arm Inside Diameter (Wear Limit), in (mm) ................. 0.2379 (6.043)
Rocker Arm Shaft Outside Diameter (Std), in (mm) ................. 0.2346-0.2358 (5.960-5.990)
Rocker Arm Shaft Outside Diameter (Wear Limit), in (mm) ................. 0.2344 (5.953)
Rocker Arm Shaft Bearing Inside Diameter (Std), in (mm) ................. 0.2362-0.2369 (6.000-6.018)
Rocker Arm Shaft Bearing Inside Diameter (Wear Limit), in (mm) ................. 0.2379 (6.043)

Cylinder Head and Valves

Number of Valves ................. 2
Cylinder Head (Max. Out of Flatness), in (mm) ................. 0.004 (0.10)
Intake Valve Clearance, in (mm) ................. 0.004-0.007 (0.11-0.19)
Exhaust Valve Clearance, in (mm) ................. 0.006-0.009 (0.16-0.24)
Intake Valve Stem Outside Diameter (Std), in (mm) ................. 0.1563-0.1569 (3.970-3.985)
Intake Valve Stem Outside Diameter (Wear Limit), in (mm) ................. 0.1535 (3.900)
Exhaust Valve Stem Outside Diameter (Std), in (mm) ................. 0.1549-0.1555 (3.395-3.985)
Exhaust Valve Stem Outside Diameter (Wear Limit), in (mm) ................. 0.1528 (3.880)
Intake Valve Guide Inside Diameter, in (mm) ................. 0.1575-0.1582 (4.000-4.018)
Exhaust Valve Guide Inside Diameter, in (mm) ................. 0.1575-0.1582 (4.000-4.018)
Valve Seat Width (Intake/Exhaust), in (mm) ................. 0.028 (0.70)
Valve Spring Free Length, in (mm) ................. 1.02 (25.80)

Piston and Piston Rings

Piston Pin Bore Inside Diameter (Std), in (mm) ................. 0.5119-0.5121 (13.002-13.008)
Piston Pin Bore Inside Diameter (Wear Limit), in (mm) ................. 0.5137 (13.048)
Piston Skirt Outside Diameter, in (mm) ................. 2.2033-2.2041 (55.965-55.985)
Piston to Cylinder Bore Clearance, in (mm) ................. 0.0006-0.0020 (0.015-0.050)
Piston Pin Outside Diameter (Std), in (mm) ................. 0.5116-0.5118 (12.994-13.000)
Piston Pin Outside Diameter (Wear Limit), in (mm) ................. 0.5100 (12.954)
Top Compression Ring Width, in (mm) ................. 0.0382-0.0390 (0.970-0.990)
Second Compression Ring Width, in (mm) ................. 0.0461-0.0469 (1.170-1.190)
Top Compression Ring to Groove Side Clearance, in (mm) ................. 0.0006-0.0020 (0.015-0.050)
Second Compression Ring to Groove Side Clearance, in (mm) ................. 0.0006-0.0020 (0.015-0.050)
Top Compression Ring End Gap, in (mm) ................. 0.006-0.012 (0.15-0.30)
Second Compression Ring End Gap, in (mm) ................. 0.012-0.018 (0.30-0.45)
Ring End Gap (Wear Limit), in (mm) ................. 0.030 (0.75)

Honda GX100 Torque Specifications

Connecting Rod Bolt (M5x0.8) ................. 5 Nm (3.6 ft-lb)
Oil Drain Plug Bolt (M10x1.25) ................. 18 Nm (13 ft-lb)
Valve Adjusting Lock Nut (M5 x0.5) ................. 7.5 Nm (5.4 ft-lb)
Flywheel Nut (M12x1.25) ................. 42 Nm (31 ft-lb)
Governor Arm Nut (M6x1.0) ................. 10 Nm (7 ft-lb)
Air Cleaner Case Bolt (M5x0.8) ................. 7 Nm (5.1 ft-lb)
Air Cleaner Cover Bolt (M6x1.0) ................. 2.3 Nm (1.7 ft-lb)
Spark Plug (M10x1.0) ................. 12 Nm (9 ft-lb)