Honda GX240 K1

Honda GX240 K1 engineThe Honda GX240 K1/T1/UT1 is a 242 cc, (14.8 cu·in) natural aspirated single-cylinder four-stroke air-cooled internal combustion small gasoline engine with a horizontal shaft, manufactured by Honda Motor Company for general-purpose applications, such as construction equipment, tillers, generators, welders, pumps and other industrial applications.

The Honda GX240 K1 engine has a single cylinder inclined by 25°, overhead valve (OHV) design, horizontal type carburetor with butterfly valve, transistorized magneto ignition system, splash type lubricating system and forced-air cooling system. The GX240 K1 engine could be equipped with single element type, dual element type, oil-bath type or a cyclone-type air cleaner. The GX240K1 used 6.0 L (1.59 US. gal. 1.32 Imp. gal.) fuel tank.

This engine produced 8.2 PS (6.0 kW; 8.0 HP) at 3,600 rpm of horsepower and 17.0 N·m (1.7 kg·m, 12.5 ft·lb) at 2,500 rpm of torque.

Engine models with other features were also available:

  • H type – 1/6 reduction type PTO, this version produced 102.0 N·m (10.2 kg·m, 74 ft·lb) at 420 rpm of peak torque;
  • L type – 1/2 reduction type PTO, it produced 34.0 N·m (3.4 kg·m, 24 ft·lb) at 1,250 rpm of torque;
  • R type – 1/2 reduction type PTO with the centrifugal clutch.

General information

Engine Specifications
Engine modelGX240 K1/T1/UT1
Engine type4-stroke, OHV, single-cylinder, inclined by 25°
Displacement242 cm3, (14.8 cu·in)
Max. horsepower8.2 PS (6.0 kW; 8.0 HP) at 3,600 rpm
Max. torque17.0 N·m (1.7 kg·m, 12.5 ft·lb) at 2,500 rpm
Cooling systemForced air
Air cleaner Dual element type;
Single element type,
Oil-bath type
Cyclone type
Lubricating systemSplash type
Ignition systemTransistorized magneto ignition
Fuel systemHorizontal type carburetor with butterfly valve
Fuel consumption313 g/kWh
Fuel tank capacity6.0 L (1.59 US. gal. 1.32 Imp. gal.)
Fuel usedUnleaded gasoline (octane number 86 or higher)
Starting systemRecoil or electric starter
Stoping systemIgnition primary circuit ground
GovernorCentrifugal govervor
PTO shaft rotationCounterclockwise (from PTO shaft side)
Dimensions (L x W X H)Type S: 35 x 450 x 410 mm (13.2 x 17.7 x 16.1 in)
Dry weightType S: 25.0 kg (55.1 lbs)

Cylinder Block and Head

A 73.0 mm (2.87 in) cylinder bore and 58.0 mm (2.28 in) piston stroke give the GX24 0K1 engine a total of 242 cc of displacement. Compression ratio rating is 8.2:1. The Honda GX240 K1 engine has a cast iron cylinder sleeve, ball bearing supported the crankshaft and heavy duty balancer shaft. The piston has two compression rings and a single oil ring.

Cylinder block
Compression ratio:8.2:1
Cylinder bore:73.0 mm (2.87 in)
Piston stroke:58.0 mm (2.28 in)
Cylinder internal diameter (standard):73.000 mm (2.874 in)
Piston skirt outer diameter (standard):72.985 mm (2.8734 in)
Number of piston rings (compression / oil):2/1
Connecting rod big end diameter (standard):33.025 mm (1.3002 in)
Connecting rod small end diameter (standard):18.005 mm (0.7089 in)
Piston pin diameter:18.000 mm (0.7087 in)
Side clearance (Top):0.015-0.045 mm (0.0006-0.0018 in)
Side clearance (Second):0.015-0.045 mm (0.0006-0.0018 in)
Side clearance (Oil):0.015-0.045 mm (0.0006-0.0018 in)
Ring end gap (Top):0.20-0.40 mm (0.0079-0.0157 in)
Ring end gap (Second):0.20-0.40 mm (0.0079-0.0157 in)
Ring end gap (Oil):0.20-0.40 mm (0.0079-0.0157 in)
Ring width (Top):2.0 mm (0.0787 in)
Ring width (Second):2.0 mm (0.0787 in)
Ring width (Oil):2.8 mm (0.1102 in)
Crankpin journal diameter:32.985 mm (1.2986 in)
Crankshaft center distance:29 mm (1.14 in)
Cylinder head
Valve arrangement:OHV, gear driven
Valve steam diameter (INTAKE):6.59 mm (0.2594 in)
Valve steam diameter (EXHAUST):6.59 mm (0.2594 in)
Valve spring free length (INTAKE):39.0 mm (1.5354 in)
Valve spring free length (EXHAUST):39.0 mm (1.5354 in)
Camshaft lobe height (INTAKE):31.52-31.92 mm (1.2409-1.2567 in)
Camshaft lobe height (EXHAUST):31.56-31.96 mm (1.2425-1.2583 in)
Camshaft journal diameter :15.984 mm (0.6293 in)

Tightening torque

Tightening torque settings
Connecting rod bolt:14 Nm; 1.4 kg·m; 10 ft·lb;
Cylinder head bolt:35 Nm; 3.5 kg·m; 25 ft·lb;
Flywheel nut:115 Nm; 11.5 kg·m; 83 ft·lb;
Rocker arm pivot lock nut:10 Nm; 1.0 kg·m; 7 ft·lb;
Rocker arm pivot bolt:24 Nm; 2.4 kg·m; 17 ft·lb;
Oil drain bolt:23 Nm; 2.3 kg·m; 17 ft·lb

Service Data

The Honda 4-stroke or an equivalent (SE or SF) oil with a viscosity of SAE 10W-30 is recommended for the GX240 K1, refilling oil capacity is 1.1 L (1.16 US. qt, 0.97 Imp. qt.). Recommended spark plug is NGK: BP6ES, BPR6ES NIPPONDENSO: W20EP-U, W20EPR-U with 0.7-0.8 mm (0.0276-0.0315 in) spark plug gap.

The valve clearance is 0.13-0.17 mm (0.0051-0.0067 in) for intake and exhaust valves. Standard cylinder compression is 6.0-8.0 kg/cm2 (85-121 psi) at 600 rpm.

Maximum speed:3,850±150 rpm
Idle speed:1,400 ±150 rpm
Cylinder compression:6.0-8.0 kg/cm2 (85-121 psi) at 600 rpm
Valve clearance
Intake valve clearance:0.15 ± 0.02 mm (0.006 ± 0.001 in)
Exhaust valve clearance:0.20 ± 0.02 mm (0.008 ± 0.001 in)
Oil system
Lubrication system:Splash type
Oil type:Honda 4-stroke or an equivalent (SE or SF)
Recommended oil:SAE 10W-30
Oil capacity:1.1 L (1.16 US. qt, 0.97 Imp. qt.)
Reduction oil capacity (centrifugal clutch):0.3 L (0.32 US. qt, 0.26 Imp. qt.)
Fuel system
Type:Horizontal type carburetor with butterfly valve
Main jet: Externally vented carburetor: #85
Internally vented carburetor: #92
Float height:13.2 mm (0.5197 in)
Pilot screw opening:2 turns out
Ignition system
Type:Transistorized magneto ignition
Ignition timing:B.T.D.C. 20° (Fixed)
Spark plug: NGK: BP6ES, BPR6ES;
Spark plug gap:0.7-0.8 mm (0.0276-0.0315 in)
Ignition coil air gap0.2-0.6 mm (0.0079-0.0079 in)


Manufacturer or BrandModels
HondaEB3000X, EB3500X, EB3800X, EM3500SX, EM3500X, EM3800SX
Author: Sergei Wers
About: Co-founder and CEO of a multi-brand auto repair shop (engine repair, chassis repair, body repair and painting) for over 15 years. I have been developing internet sites with technical specifications for more than seven years.

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We try to use official documentation and verify the published data, but errors may occur. In addition, specifications of machinery and equipment may vary depending on markets and modifications. We do not recommend the use of this data for spare parts or repairs. Use official service manuals or parts catalogs for your product.

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