Honda G100 K1

Honda G100 K1 2.2 HPThe Honda G100 K1 is a 83 cc (5.06 single-cylinder air-coolled 4-stroke internal combustion small gasoline engine manufactured by Honda Motor Company since 1980. The G100 K1 is the second generation of this engine. It has larger cylinder bore and, as a result, larger displacement.

The Honda G100 engine has a slide valve (L-head) design and camshaft driven by a single row chain driven by the crankshaft. The engine has an electric or recoil starter, horizontal carburetor with butterfly valve and transistorized magneto or contact point breaker (CDI) ignition system.

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

The G100K1 engine a compression ratio rating is 6.5:1, cylinder bore and piston stroke are 48.0 mm (1.88 in) and 46.0 mm (1.81 in), respectively.

The Honda G100 K1 produced 2.2 HP (1.64 kW) at 4200 rpm of maximum horsepower and 3.8 Nm (0.38 kg·m) of torque.

General information

Engine Specifications
ModelG100 K1
Type4-stroke, side valve type (L-head), single cylinder
Displacement83 cm 3 (5.06 cu-in)
Max. horsepower2.2 HP (1.64 kW) at 4200 rpm
Max. torque3.8 Nm (0.38 kg·m)
CarburetorHorizontal, butterfly valve
Cooling systemForced-air
Ignition systemTransistorized magneto or CDI
Lubricating systemSplash system
Starting systemRecoil starter
Stoping systemGround of primary circuit
Fuel usedUnleaded gasoline (octane number 86 or higher)
Fuel tank capacity1.4 L
Fuel consumption320 g/HPh
PTO shaft rotationCounterclockwise (from PTO shaft side)

Cylinder Block and Head

Cylinder block
Compression ratio:6.5:1
Bore x Stroke48 x 46 mm (1.88 in x 1.81 in in)
Sleeve internal diameter48.00 mm (1.88 in)
Piston skirt outer diameter47.995 mm (1.8503 in)
Number of piston rings (compression / oil):2 / 1
Ring side clearanceTop/second/oil0.01-0.05 mm (0.0004-0.002 in)
Ring end gapTop/second0.25 mm (0.009 in)
Oil0.45 mm (0.017 in)
Connecting rod small end ID10.0 mm (0.393 in)
Connecting rod big end ID18.0 mm (0.708 in)
Crankpin outer diameter17.98 mm (0.707 in)
Cylinder Head
Warpage (limit)0.10 mm (0.004 in)
Valve Arrangement:Side valve type (L-head)
Stem outer diameter (standard):INTAKE5.490 mm (0.2161 in)
EXHAUST5.445 mm (0.2143 in)
Guide internal diameterINTAKE / EXHAUST5.5 mm (0.2165 in)
Spring free length27.1 mm (1.066 in)
Cam height:INTAKE20.82 mm (0.8196 in)
EXHAUST20.82 mm (0.8196 in)
Camshaft journal diameter:12.184 mm (0.4796 in)

Maintenance data

Idle speed1400 ± 110 rpm
Cylinder compression6.5 kg/cm2 (637 kPa) at 800 rpm
Adjust timing ignition
Ignition timing20° B.T.D.C. (Fixed)
Adjust valve clearance
Intake valve0.08-0.16 mm (0.0031-0.0063 in)
Exhaust valve0.08-0.16 mm (0.0031-0.0063 in)
Oil system
Oil typeHonda 4-stroke “SE”
Recommended oil10W-40
Oil capacity0.45 L
Main jet#62
Ignition system
Spark plug NGK: BM4A, BMR4A
Spark plug gap0.6-0.7 mm (0.024-0.028 in)
Primary ignition coil resistance0.7-0.9 kΩ
Secondary ignition coil resistance6.3-7.7 kΩ

Tightening torque specs

Tightening torque specs
Carburetor4-6 Nm; 0.4-0.6 kg·m; 2.9-4.3 ft·lb
Flywheel45-55 Nm; 4.5-5.5 kg·m; 32.5-40 ft·lb
Governor arm8-12 Nm; 0.8-1.2 kg·m; 5.8-8.7 ft·lb
Cylinder head8-12 Nm; 0.8-1.2 kg·m; 5.8-8.7 ft·lb
Crankcase cover8-12 Nm; 0.8-1.2 kg·m; 5.8-8.7 ft·lb
Connecting rod4-6 Nm; 0.4-0.6 kg·m; 2.9-4.3 ft·lb
5 mm bolts, nuts4-7 Nm; 0.4-0.7 kg·m; 2.9-5.1 ft·lb
6 mm bolts, nuts8-12 Nm; 0.8-1.2 kg·m; 5.8-8.7 ft·lb
8 mm bolts, nuts20-28 Nm; 2.0-2.8 kg·m; 14.5-20.3 ft·lb
10 mm bolts, nuts35-40 Nm; 3.5-4.0 kg·m; 25-29 ft·lb
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    • Hi just wandering on a honda G100 K1 engine what size is the PTO shaft please I’m interested in buying one just wanted to check if it’s suitable?

  1. Hello there I’m interested in purchasing a Honda G100 2.2 hp engine just wandering what size shaft it is please

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