The Honda GX100 is a 98 cc (6.0 cu-in) single-cylinder air-cooled 4-stroke internal combustion small gasoline engine manufactured by Honda Motor Company for general-purpose applications, such as commercial lawn and garden equipment, construction and industrial equipment, agricultural equipment and water pumps.
This engine has an OHC design for increased efficiency and optimal power transfer; high compression ratio for better fuel efficiency; horizontal type carburetor with butterfly valve; sophisticated air intake system; large capacity, multi-chamber exhaust system, heavy-duty recoil starter and transistorized magneto ignition system.
A 56.0 mm (2.2 in) cylinder bore and 40.0 mm (1.60 in) piston stroke give the Honda GX100 engine a total of 98 cc of displacement. Compression ratio rating is 8.5:1. It produced 2.2 kW (3.0 PS) of horsepower at 3,600 rpm and 5.7 N·m (0.59 kg·m, 4.2 ft·lb) of torque at 3,600 rpm.
General information
| Engine Specifications | |
| Model | GX100 |
| Type | 4-stroke, OHC, single cylinder |
| Displacement | 98 cm 3 (6.0 cu-in) |
| Max. horsepower | 3.0 PS (2.2 kW) at 3,600 rpm |
| Max. torque (crank PTO) | 5.7 N·m (0.59 kg·m, 4.2 ft·lb) at 3,600 rpm |
| Carburetor | Horizontal type, butterfly valve |
| Cooling system | Forced-air |
| Ignition system | Transistorized magneto ignition |
| Lubricating system | Splash |
| Starting system | Recoil starter |
| Stoping system | Ignition primary circuit ground |
| Fuel used | Unleaded gasoline (octane number 86 or higher) |
| Fuel tank capacity | 1.2 L (0.32 US Gal, 0.26 Imp Gal.) |
| Fuel consumption | 240 g/PSh |
| PTO shaft rotation | Counterclockwise (from PTO shaft side) |
Cylinder Block and Head
The Honda GX100 has cast iron cylinder sleeve, ball bearing supported forged steel crankshaft, improved piston design. The piston has two compression rings and one oil ring. Precision camshaft design offers precise valve timing and optimal valve overlap for better fuel efficiency.
| Cylinder block | ||
| Compression ratio: | 8.5:1 | |
| Bore x Stroke | 56 X 40 mm (2.2 x 1.6 in) | |
| Sleeve internal diameter | 56.00 mm (2.2047 in) | |
| Piston skirt outer diameter | 55.965-55.985 mm (2.2033-2.2041 in) | |
| Number of piston rings (compression / oil): | 2 / 1 | |
| Ring side clearance | Top | 0.015-0.050 mm (0.0006-0.0020 in) |
| Second/oil | 0.015-0.050 mm (0.0006-0.0020 in) | |
| Ring end gap | Top | 0.15-0.30 mm (0.006-0.012 in) |
| Second | 0.30-0.45 mm (0.012-0.018 in) | |
| Connecting rod small end ID | 13.005-13.020 mm (0.5120-0.5126 in) | |
| Crankshaft crank pin outer diameter | 23.970-23.980 mm (0.9437-0.9441 in) | |
| Cylinder Head | ||
| Warpage (limit) | 0.10 mm (0.004 in) | |
| Valve Arrangement: | OHC | |
| Valves: | 2 | |
| Stem outer diameter (standard): | INTAKE | 3.970-3.985 mm (0.1563-0.1569 in) |
| EXHAUST | 3.935-3.950 mm (0.1549-0.1555 in) | |
| Cam height: | INTAKE | 36.483 mm (1.4363 in) |
| EXHAUST | 36.483 mm (1.4363 in) | |
| Valve spring free length: | 25.8 mm (1.02 in) | |
Tightening torque specs
| Tightening torque specs | |
| Connecting rod bolt | 5 Nm; 0.5 kg·m; 3.6 ft·lb |
| Oil dran plug bolt | 18 Nm; 1.8 kg·m; 13 ft·lb |
| Valve adjusting lock nut | 7.5 Nm; 0.75 kg·m; 5.4 ft·lb |
| Flywheel nut | 42 Nm; 4.3 kg·m; 31 ft·lb |
| Governor arm nut | 10 Nm; 1.0 kg·m; 7 ft·lb |
| Stopper plate screw | 1 Nm; 0.1 kg·m; 0.7 ft·lb |
| Spark plug | 11.8 Nm; 1.2 kg·m; 8.7 ft·lb |
Service Information
| Engine | |
| Maximum speed | 4000 ± 200 rpm |
| Idle speed | 1550 ± 150 rpm |
| Cylinder compression | 5.0 kg/cm2 (71 psi) at 700 rpm |
| Valve clearance | |
| Intake valve | 0.15 ± 0.04 mm (0.006 ± 0.002 in) |
| Exhaust valve | 0.20 ± 0.04 mm (0.008 ± 0.002 in) |
| Oil system | |
| Oil type | Honda 4-stroke or an equivalent (SE or SF) |
| Recommended oil | SAE 10W-30 |
| Oil capacity | 0.4 L (0.42 US. qt, 0.35 Imp. qt.) |
| Carburetor | |
| Main jet | #60 |
| Pilot jet | #35 |
| Float height | 12 mm (0.47 in) |
| Pilot screw opening | 2-3/8 turns out |
| Ignition system | |
| Spark plug | NGK: CR5HSB DENSO: U16FSR-UB |
| Spark plug gap | 0.7-0.8 mm (0.028-0.031 in) |
Hello I am trying to replace GX100 GCAGK QXB4. That has sized the bigend.
And a broken conrod . beast option replace it with new engine .Not a bit of it. I am tolled we must rebuild rebuild old unit .Is this really the case????? thank You