Honda G100 K2

Honda G100 K2, 2.5 HPThe Honda G100 K2 is a 98 cc (6.0 4-stroke, single-cylinder, air-coolled internal combustion small gasoline engine manufactured by Honda Motor Company.

The Honda G100K2 engine has a slide valve (L-head) design and camshaft driven by a single row chain driven by the crankshaft. The engine has a recoil starter, horizontal carburetor with butterfly valve and transistorized magneto ignition system.

The G100 K2 engine a compression ratio rating is 6.5:1, cylinder bore and piston stroke are 52.0 mm (20.5 in) and 46.0 mm (1.81 in), respectively. The Honda G100 produced 2.5 HP at 4200 rpm of maximum horsepower and 4.5 Nm (0.45 kg·m, 3.3 ft·lb) of maximum torque, depending on the engine application.

There are three versions of G100 engine:

  • Honda G100, with 76 cc of displacement and 2.0 HP or 2.2 HP of horsepower
  • Honda G100 K1, with 83 cc of displacement and 2.2 HP
  • Honda G100 K2, with 98 cc of displacement and 2.5 HP of maximum output power

General information

Engine Specifications
Model G100 K2
Type 4-stroke, side valve type (L-head), single cylinder
Displacement 98 cm 3 (6.0 cu-in)
Max. horsepower 2.0 HP (1.5 kW) at 4200 rpm
Max. torque 3.5 Nm (0.35 kg·m, 2.5 ft·lb)
Carburetor Horizontal, butterfly valve
Cooling system Forced-air
Ignition system Transistorized magneto
Lubricating system Splash system
Starting system Recoil starter
Stoping system Ground of primary circuit
Fuel used Unleaded gasoline (octane number 86 or higher)
Fuel tank capacity 1.4 L
Fuel consumption 320 g/HPh
PTO shaft rotation Counterclockwise (from PTO shaft side)

Cylinder Block and Head

Cylinder block
Compression ratio: 6.5:1
Bore x Stroke 52 x 46 mm (20.5 in x 1.81 in in)
Sleeve internal diameter 52.00 mm (20.5 in)
Cylinder Head
Warpage (limit) 0.10 mm (0.004 in)
Valve Arrangement: Side valve type (L-head)
Valves: 2

Maintenance data

Idle speed 1400 ± 110 rpm
Cylinder compression 6.5 kg/cm2 (637 kPa) at 800 rpm
Adjust timing ignition
Ignition timing 20° B.T.D.C. (Fixed)
Adjust valve clearance
Intake valve 0.08-0.16 mm (0.0031-0.0063 in)
Exhaust valve 0.08-0.16 mm (0.0031-0.0063 in)
Oil system
Oil type Honda 4-stroke “SJ”
Recommended oil 10W-40
Oil capacity 0.45 L
Ignition system
Spark plug NGK: BPMR-4A
Spark plug gap 0.6-0.7 mm (0.024-0.028 in)

Tightening torque specs

Tightening torque specs
Carburetor 4-6 Nm; 0.4-0.6 kg·m; 2.9-4.3 ft·lb
Flywheel 45-55 Nm; 4.5-5.5 kg·m; 32.5-40 ft·lb
Governor arm 8-12 Nm; 0.8-1.2 kg·m; 5.8-8.7 ft·lb
Cylinder head 8-12 Nm; 0.8-1.2 kg·m; 5.8-8.7 ft·lb
Crankcase cover 8-12 Nm; 0.8-1.2 kg·m; 5.8-8.7 ft·lb
Connecting rod 4-6 Nm; 0.4-0.6 kg·m; 2.9-4.3 ft·lb
5 mm bolts, nuts 4-7 Nm; 0.4-0.7 kg·m; 2.9-5.1 ft·lb
6 mm bolts, nuts 8-12 Nm; 0.8-1.2 kg·m; 5.8-8.7 ft·lb
8 mm bolts, nuts 20-28 Nm; 2.0-2.8 kg·m; 14.5-20.3 ft·lb
10 mm bolts, nuts 35-40 Nm; 3.5-4.0 kg·m; 25-29 ft·lb
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We try to use verified sources and official documentation, however, differences between sources or errors in entering information may occur. We do not provide advice on technical issues related to the engines operation or repair. We do not recommend using provided information for engines repairing engines or spare parts ordering, use only official service manuals and spare-parts catalogs.


  1. this artical was very helpful,but it left out my main question, can i use a k2 connecting rod in my k1 engine..rerering to the g100 generator engine family.

  2. The specifications for The Honda G100 K2(98cc) model are very comprehensive, but it does not state the width and length of the PTO shaft! – Can any one help? – kind regards, Jeff.

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