Honda GX270 K1/T1/UT1

Honda GX270 engineThe Honda GX270 K1/T1/UT1 is a 270 cc (16.5 cu-in) single-cylinder (inclined by 25 °), air-cooled, four-stroke cycle, internal combustion small gasoline engine manufactured by Honda Motor Company.

This engine has an OHV design with two valves; sophisticated air intake system; large capacity, multi-chamber exhaust system; heavy-duty recoil starter.

The Honda GX270 K1/T1/UT1 engine produces 9.12 PS (9.0 HP, 6.7 kW) at 3,600 rpm of max output power and 19.5 Nm (2.0 kg·m; 14.4 lbf·ft) at 2,500 rpm of peak torque. With 1/2 reduction it produces 39.0 Nm (3.9 kg·m, 28.0 lbf·ft) of torque at 1,250 rpm, with 1/6 reduction up to 117.0 Nm (11.7 kg·m, 85.0 lbf·ft) at 2,000 rpm.

From spring 2010 onwards, Honda producing the updated version of GX270 engines. This engine meets the most stringent exhaust gas emission regulation, EPA Phase III.

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°
Displacement270 cm 3 (16.5 cu-in)
Max. horsepower9.1 PS (6.7 KW; 9.0 HP) at 3,600 rpm
Max. torque (crank PTO)19.5 Nm (2.0 kg·m; 14.4 lbf·ft) at 2,500 rpm
CarburetorHorizontal type, butterfly valve
Cooling systemForced-air
Ignition systemTransistorized magneto ignition
Lubricating systemSplash type
Starting systemRecoil or electric starter
Stoping systemIgnition primary circuit ground
Fuel usedUnleaded gasoline (octane number 86 or higher)
Fuel tank capacity6.0 liters (6.3 US.qts, 5.3 Imp. qts)
Fuel consumption313 g/kWh (230 g/HPh, 0.51 lb/HPh)
PTO shaft rotationCounterclockwise (from PTO shaft side)

Dimensions and Weight

Type SType QType LType RType HType WType PType V
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 GX270 has 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 Stroke77.0 X 58.0 mm (3.0 x 2.3 in)
Sleeve internal diameter77.000 mm (3.031 in)
Piston skirt outer diameter76.985 mm (3.0309 in)
Number of piston rings (compression / oil):2 / 1
Piston ring side clearance (Top):0.015-0.045 mm (0.0006-0.0018 in)
Piston ring side clearance (Second):0.015-0.045 mm (0.0006-0.0018 in)
Piston ring side clearance (Oil):0.015-0.045 mm (0.0006-0.0018 in)
Piston ring end gap (Top):0.200-0.400 mm (0.01-0.02 in)
Piston ring end gap (Second):0.200-0.400 mm (0.01-0.02 in)
Piston ring end gap (Oil):0.200-0.700 m (0.01-0.03 in)
Ring width (Top):2.0 mm (0.08 in)
Ring width (Second):2.0 mm (0.08 in)
Crankshaft outer diameter32.985 mm (1.2986 in)
Cylinder Head
Warpage (limit)0.10 mm (0.004 in)
Valve Arrangement:Overhead valve (OHV)
Valve stem outer diameter (INTAKE):6.590 mm (0.259 in)
Valve stem outer diameter (EXHAUST):6.550 mm (0.258 in)
Camshaft cam height (INTAKE):31.520-31.920 mm (1.241-1.257 in)
Camshaft cam height (EXHAUST):31.560-31.960 mm (1.243-1.258 in)
Camshaft outer diameter:15.984 mm (0.6293 in)

Maintenance data

Maximum speed3,850 ± 150 rpm
Idle speed1,400 ± 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: #88
Internally vented carburetor bowl: #95
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 liters (1.16 US.qts, 0.97 Imp. qts)
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 Ω
Secondary ignition coil resistance5.9-7.1 kΩ
Ignition coil air gap0.4 ± 0.2 (0.016 ± 0.008)
Starter motor
Brush length7.2 mm (0.28 in) limit: 3.5 mm (0.14 in)
Mica depth1.0 mm (0.04 in) limit: 0.2 mm (0.01 in)

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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