Honda H4518

Honda H4518The Honda H4518 is a lawn tractor with Honda GX640 two-cylinder water-cooled gasoline engine 0.64 l (635 cc, 38.7 cu-in). The Honda H4518H used hydrostatic transmission and 965 mm (38 in.), 1190 mm (42 in.) or 1,168 mm (46 in) mower deck. The mower deck is adjustable in seven increments for cutting heights between 25 mm (1 in.) and 100 mm (4 in). The Honda H4518 lawn tractor was produced from 1991 to 1998.

The GX640 engine produced 18.0 HP (13.2 kW) at 3,600 rpm of maximum output power and 46.1 Nm (4.7 kg·m, 34.0 ft·lb) at 2,500 rpm of maximum torque. The GX640 is a liquid-cooling engine with a 76.0 mm (3.0 in) of the cylinder bore and a 70.0 mm (2.8 in) of the piston stroke, and 8.0:1 compression ratio rating.

The H4518 is equepped with hydrostatic transmission. This transmission has three approximate ground speeds: “Reverse” to 3.4 km/h (2.1 mph), “Mowing” to 5.1 km/h (3.2 mph) and “Transport” to 7.6 km/h (4.7 mph)

General information

General Specifications
ModelHonda H4518H
Length1,815 mm (71.5 in)
Width 38 inch deck type: 1,270 mm (50.0 in)
42 inch deck type: 1,460 mm (57.5 in)
46 inch deck type: 1,530 mm (60.2 in)
Height1,052 mm (41.4 in)
Wheel base1190 mm (46.9 in.)
Dry weight 38 inch deck type: 290.0 kg (639.5 lbs)
42 inch deck type: 302.0 kg (655.9 lbs)
46 inch deck type: 304.0 kg (670.3 lbs)
Fuel tank capacity9.0 l (2.38 US gal., 1.98 Imp gal.)
Engine modelHonda GX630
Displacement635 cm3 (38.7 cu-in)
Bore x stroke76.0 x 70.0 mm (3.0 x 2.8 in.)
Max. horsepower18.0 HP (13.2 kW) at 3,600 rpm
Max. torque46.1 Nm (4.7 kg·m, 34.0 ft·lb) at 2,500 rpm
CarburetorHorizontal type, butterfly valve
Cooling systemLiquid-cooling
Ignition systemCDI ignition
Lubricating systemForced oil by trochoid pump
Starting systemElectric starter
Stoping systemCut off the power supply to the CDI (Open)
Fuel usedUnleaded gasoline (octane number 86 or higher)
Hydrostatic type transmission
TypeOil pressure-type variable-speed transmission
Groung speeds Reverse: 3.4 km/h (2.1 mph)
Mowing: 5.z km/h (3.2 mph)
Transport: 7.6 km/h (4.7 mph)
Wheels and tires
Front tires size15×6.0-6
Front tires pressure98 kPa (1.0 kg/cm2, 14 psi)
Rear tires size20.5×8.5-10
Rear tires pressure79 kPa (0.8 kg/cm2, 11.4 psi)
Mower Deck
Deck size965 mm (38 in.), 1,060 mm (42 in.) or 1,168 (46 in.)
Height range25-100 mm (1-4 in.)

Maintenance data

Idle speed1,400 ± 150 rpm
Cylinder compression4.0-7.0 kg/cm2 (57-100 psi) at 350 rpm
Valve clearance
Intake valve0.10-0.14 mm (0.004-0.006 in)
Exhaust valve0.18-0.22 mm (0.007-0.009 in)
Main jet#98
Float height14.0 mm (0.55 in)
Pilot screw opening1-1/2 turns out
Oil system
Oil typeHonda 4-stroke or an equivalent (SE or SF)
Recommended oilSAE 10W-40
Oil capacity (without filter changed)2.0 L (2.11 US qt, 1.76 Imp qt)
Oil capacity (with filter changed)2.3 L (2.43 US qt, 2.02 Imp qt)
Oil pressure3.0-4.0 kg/cm2 (43-57 psi) at 350 rpm
Start opening82° C (180° F)
Fully open95° C (203° F)
Lift height8.0 mm (0.31 in)
Temperature range for continuity110° ± 2° C (230° ± 36° C)
Oil pump
Tip clearance (standard)0.14 mm (0.006 in)
Outer rotor clearance (standard)0.15-0.21 mm (0.006-0.008 in)
Pump end clearance0.04-0.09 mm (0.0016-0.0035 in)
Ignition system
Ignition timing22 ° B.T.D.C
Spark plug NGK: BPR5ES-11
Spark plug gap1.0-1.1 mm (0.039-0.043 in)
Primary side ignition coil resistance0.37-0.50 Ω
Secondary side ignition coil resistance8.0-9.3 kΩ
Starter motor
Brush length14 mm (0.55 in), limit: 9.0 mm (0.35 in)
Mica depth (limit)0.2 mm (0.008 in)
Hydrostatic transmission lube
Transmission oil typeHonda hydrostatic transmission oil


Honda 38″ mid-mount mower deck
Cutting width960 mm (38 in)
Honda 42″ mid-mount mower deck
Cutting width1,060 mm (42 in)
Honda 46″ mid-mount mower deck
Cutting width1,160 mm (46 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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