Honda GX240 K1/T1/UT1

Honda GX240 engineThe Honda GX240 K1/T1/UT1 is a 0.24 l (242 cc) single-cylinder air-cooled 4-stroke internal combustion small gasoline engine manufactured by Honda Motor Company for general-purpose applications.

This engine has an OHV design for increased efficiency and optimal power transfer; sophisticated air intake system; large capacity, multi-chamber exhaust system; heavy-duty recoil starter.

The Honda GX240 K1 produces 8.11 PS (8.0 HP, 6.0 kW) at 3600 rpm and 17 Nm (1.7 kg·m, 12 ft·lb) of torque at 2500 rpm.

The GX240 K1/T1/UT1 is an old version, nowadays Honda Motor Co. produces a new GX240 R2/RT2/T2/U2/UT2 engine with CDI ignition system.

PTO Shaft Options

  • E type – tapered shaft;
  • H type – 1/6 reduction type PTO;
  • L type – 1/2 reduction type PTO;
  • P type – threaded type (SAE);
  • Q type – straight shaft;
  • R type – 1/2 reduction type PTO with centrifugal clutch;
  • V type – tapered shaft;

General information

Engine Specifications
Type4-stroke, OHV, single cylinder, inclined by 25°
Displacement242 cm 3 (14.8 cu-in)
Max. horsepower8.11 PS (8.0 HP, 6.0 kW) at 3600 rpm
Max. torque (crank PTO)17 Nm (1.7 kg·m, 12 ft·lb) at 2500 rpm
CarburetorHorizontal type, butterfly valve
Cooling systemForced-air
Ignition systemTransistorized magneto ignition
Lubricating systemSplash
Starting systemRecoil or electric starter
Stoping systemIgnition primary circuit ground
Fuel usedUnleaded gasoline (octane number 86 or higher)
Fuel tank capacity6.0 L (1.59 US gal, 1.32 lmp gal)
Fuel consumption313 g/kWh (230 g/HPh, 0.51 lb/HPh)
PTO shaft rotationCounterclockwise (from PTO shaft side)

Dimensions and Weight

Length, mm (in)355 (14.0)380 (15.0)405 (15.9)440 (17.3)425 (16.7)370 (14.6)380 (15.0)400 (15.7)
Width, mm (in)430 (16.9)
Height, mm (in)410 (16.1)
Dry weight, kg (lb)25 (55.1)25 (55.1)26.5 (58.4)30 (66.1)26.5 (58.4)25 (55.1)25 (55.1)25 (55.1)
weight, kg (lb)
30 (66.1)30 (66.1)31.5 (69.4)35 (77.2)31.5 (69.4)30 (66.1)30 (66.1)30 (66.1)

Cylinder Block and Head

The Honda GX240 engine has a cast iron cylinder sleeve, ball bearing supported crankshaft, improved piston design, heavy duty balancer shaft. 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:8.2
Bore x Stroke73 X 58 mm (2.9 x 2.3 in)
Sleeve internal diameter73.00 mm (2.874 in)
Piston skirt outer diameter72.985 mm (2.8734 in)
Number of piston rings (compression / oil):2 / 1
Ring side clearanceTop/second/oil0.015-0.045 mm (0.0006-0.0018 in)
Ring end gapTop/second0.2-0.4 mm (0.01-0.02 in)
Oil0.2-0.4 m (0.01-0.02 in)
Ring widthTop/second2.0 mm (0.08 in)
Oil2.8 mm (0.110 in)
Crankshaft outer diameter32.985 mm (1.2986 in)
Cylinder Head
Warpage (limit)0.10 mm (0.004 in)
Valve Arrangement:OHV
Stem outer diameter (standard):INTAKE6.59 mm (0.259 in)
EXHAUST6.55 mm (0.258 in)
Cam height:INTAKE31.52-31.92 mm (1.241-1.257 in)
EXHAUST31.56-31.96 mm (1.243-1.258 in)
Camshaft outer diameter:15.984 mm (0.6293 in)


Maximum speed3850 ± 150 rpm
Idle speed1400 ± 150 rpm
Cylinder compression6.0-8.5 kg/cm2 (85-151 psi) at 600 rpm
Valve clearance
Intake valve0.15 ± 0.02 (0.006 ± 0.001)
Exhaust valve0.20 ± 0.02 (0.008 ± 0.001)
Main jetExternally vented carburetor bowl: #85
Internally vented carburetor bowl: #92
Float height13.2 mm (0.52 in)
Pilot screw opening2
Oil system
Oil typeHonda 4-stroke or an equivalent (SG.SF/CC.CD)
Recommended oilSAE 10W-30
Oil capacity1.1 L (1.16 US qt, 0.97 lmp qt)
Ignition system
Ignition timing20 ° B.T.D.C (Fixed)
Spark plugNGK: BP6ES, BPR6ES
Spark plug gap0.7-0.8 mm (0.028-0.031 in)
Spark plug cap7.5-12.5 kΩ
Primary ignition coil resistance0.8-1.0 kΩ
Secondary ignition coil resistance5.9-7.1 kΩ
Ignition coil air gap0.4 ± 0.2 (0.016 ± 0.008)

Tightening torque specs

Tightening torque specs
Connecting rod bolt (M8x1.25 Special)14 Nm; 1.4 kg·m; 10 ft·lb
Cylinder head bolt (M10x1.25)35 Nm; 3.5 kg·m; 25 ft·lb
Flywheel nut (M16x1.5 Special)115 Nm; 11.5 kg·m; 83 ft·lb
Rocker arm pivot lock nut (M6x0.5)10 Nm; 1.0 kg·m; 7 ft·lb
Rocker arm pivot bolt (M8x1.25 Special)24 Nm; 2.4 kg·m; 17 ft·lb
Crankcase cover bolt (M8x1.25)24 Nm; 2.4 kg·m; 17 ft·lb
Oil level switch joint nut (M10x1.25)10 Nm; 1.0 kg·m; 7 ft·lb
Fuel filter joint nut (M10x1.25)2 Nm; 0.2 kg·m; 1.4 ft·lb
Muffler mounting nut (M8x1.25)24 Nm; 2.4 kg·m; 17 ft·lb
Air cleaner wing nut (M6x1.0)9 Nm; 0.9 kg·m; 6.5 ft·lb
Oil drain bolt (M12x1.5)23 Nm; 2.3 kg·m; 17 ft·lb
Fuel tank bolt (M8x1.25)24 Nm; 2.4 kg·m; 17 ft·lb
Air cleaner mounting nut (M6x1.0)10 Nm; 1.0 kg·m; 7 ft·lb
Fuel strainer cup (M24x1.0)4 Nm; 0.4 kg·m; 2.9 ft·lb
Standard torque values
Bolt, nut (5 mm)5.5 Nm; 0.55 kg·m; 4.0 ft·lb
Bolt, nut (6 mm)10 Nm; 1.0 kg·m; 7 ft·lb
Bolt, nut (8 mm)24 Nm; 2.4 kg·m; 17 ft·lb
Bolt, nut (10 mm)37.5 Nm; 3.75 kg·m; 27 ft·lb
Bolt, nut (12 mm)55 Nm; 5.5 kg·m; 40 ft·lb

Engine applications

  • Pressure washers
  • Commercial lawn and garden equipment
  • Tillers / cultivators
  • Generators
  • Construction / industrial equipment
  • Agricultural equipment
  • Small vehicles
  • Water pumps
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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    • Hi Jim, long time since your post, not sure if you have an answer or still interested, my predicament as well. last year bought a Chinese knock off, cheap brand says Farmer Tec, box says “fits Honda GX 240”, which it does but not exactly the specs of the original Keihin. My engine, on a generator, 30 years old but little work, 242 cc I believe the modern GX 240 has the same 270 cc capacity so the replacement carby has a larger venturi diameter and a larger main jet, the result is the revs hunt up and down. I have tried replacing the main jet with the one from the Keihin, still no good next I will try to close down the venturi, 17.4 to 15.9mm and hope that works, had thought about trying to see if the likes of Kawasaki, Yamaha have one like it?

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