Honda GX610 U1/R1

Honda GX610 U1/R1The Honda GX610 U1/R1 is a 614 cc, (37.5 cu·in) natural aspirated V-twin four-stroke air-cooled internal combustion small gasoline engine with a horizontal shaft, manufactured by Honda Motor Company for general-purpose applications.

The cylinder bore is 77.0 mm (3.03 in) and the piston stroke is 66.0 mm (2.6 in). The compression ratio rating is 8.3:1.

The GX610 U1/R1 engine produced 16.9 PS (12.4 kW; 16.6 HP) at 3,600 rpm of maximum horsepower and 39.6 N·m (4 kg·m, 29.2 ft·lb) at 2,500 rpm of maximum torque.

The Honda GX610 U1/R1 features:

  • Overhead valve (OHV) design
  • Transistorized magneto ignition system
  • Horizontal type carburetor with butterfly valve
  • Centrifugal governor
  • Forced lubrication system
  • Forced air cooling system
  • Recoil or electric starter

General information

Engine Specifications
Engine modelGX610 U1/R1
Engine type4-stroke, OHV, V-twin
Displacement614 cm3, (37.5 cu·in)
Max. horsepower16.9 PS (12.4 kW; 16.6 HP) at 3,600 rpm
Max. torque39.6 N·m (4 kg·m, 29.2 ft·lb) at 2,500 rpm
Cooling systemForced air
Air cleanerDual element type
Lubricating systemForced lubrication
Ignition systemTransistorized magneto ignition
Fuel systemHorizontal type carburetor with butterfly valve
Fuel consumption313 g/kWh
Fuel usedUnleaded gasoline (octane number 86 or higher)
Starting systemRecoil or electric starter
Stoping systemIgnition primary circuit ground
GovernorCentrifugal governor
PTO shaft rotationCounterclockwise (from PTO shaft side)
Dimensions (L x W X H)388 x 457 x 452 mm (15.3 x 18 x 17.8 in)
Dry weight42.0 kg (92.6 lbs)

Cylinder Block and Head

Cylinder block
Compression ratio:8.3:1
Cylinder bore:77.0 mm (3.03 in)
Piston stroke:66.0 mm (2.6 in)
Cylinder internal diameter (standard):77.000 mm (3.0315 in)
Piston skirt outer diameter (standard):76.985 mm (3.0309 in)
Number of piston rings (compression / oil):2/1
Connecting rod small end diameter (standard):18.005 mm (0.7089 in)
Piston pin diameter:18.000 mm (0.7087 in)
Side clearance (Top):0.030-0.060 mm (0.0012-0.0024 in)
Side clearance (Second):0.030-0.060 mm (0.0012-0.0024 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 width (Top):1.990 mm (0.0783 in)
Ring width (Second):1.990 mm (0.0783 in)
Crankshaft main journal diameter:38.000 mm (1.4961 in)
Crankpin journal diameter:39.995 mm (1.5746 in)
Crankshaft center distance:33 mm (1.3 in)
Cylinder head
Valve arrangement:OHV, gear driven
Valves:2,(4 valves in total)
Valve steam diameter (INTAKE):6.590 mm (0.2594 in)
Valve steam diameter (EXHAUST):6.550 mm (0.2579 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):29.865 mm (1.1758 in)
Camshaft lobe height (EXHAUST):29.865 mm (1.1758 in)
Camshaft journal diameter :16.985 mm (0.6687 in)

Tightening torque specs

Tightening torque specs
Connecting rod bolt12 Nm; 1.2 kg·m; 9 ft·lb
Cylinder head bolt34 Nm; 3.5 kg·m; 25 ft·lb
Socket bolt27 Nm; 2.7 kg·m; 20 ft·lb
Flywheel nut196 Nm; 20.0 kg·m; 145 ft·lb
Pivot bolt24 Nm; 2.4 kg·m; 17 ft·lb
Pivot adjusting nut10 Nm; 1.0 kg·m; 7 ft·lb
Cylinder head cover bolt9 Nm; 0.9 kg·m; 6.5 ft·lb
Oil level switch joint nut10 Nm; 1.0 kg·m; 7 ft·lb
Oil drain bolt39 Nm; 4.0 kg·m; 29 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)22 Nm; 2.2 kg·m; 16 ft·lb
Bolt, nut (10 mm)34 Nm; 3.5 kg·m; 25 ft·lb
Bolt, nut (12 mm)54 Nm; 5.5 kg·m; 40 ft·lb

Service Data

Maximum speed:3,850±150 rpm
Idle speed:1,400 ±150 rpm 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:Forced lubrication
Oil type:Honda 4-stroke or an equivalent (SG or SF)
Recommended oil:SAE 10W-30 or 10W-40
Oil capacity:1.50 L (1.59 US. qt, 1.32 Imp. qt.)
Fuel system
Type:Horizontal type carburetor with butterfly valve
Ignition system
Type:Transistorized magneto ignition
Ignition timing:B.T.D.C. 20° (Fixed)
Spark plug:NGK: ZGR5A DENSO: J16CR-U
Spark plug gap:0.7-0.8 mm (0.0276-0.0315 in)
Spark plug torque:18 N·m (1.8 kg·m, 13.3 ft·lb)
Ignition coil air gap0.2-0.6 mm (0.0079-0.0236 in)
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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