Honda GC135

Honda GC135 engineThe Honda GC135 is a small (135 cc) single-cylinder air-cooled 4-stroke internal combustion gasoline engine with horizontal shaft, manufactured by Honda Motor Company since 1997 for general-purpose applications.

This engine has a single-cylinder, compact combustion chamber, tough resin overhead cam for durability and quietness and uniblock construction reduce fuel consumption. The Honda GC135 engine has transistorized magneto ignition, horizontal type carburetor, and recoil starter.

A 64 mm (2.5 in) cylinder bore and 42 mm (1.7 in) piston stroke give the engine a total of 135 cc of displacement. Compression ratio is 8.5:1. It produces 2.9 kW (4.0 HP) at 3,600 rpm and 8.6 N·m (0.88 kg·m, 6.4 ft·lb) of torque at 2,500 rpm.

General information

Engine Specifications
ModelGC135
Type4-stroke, OHV, single cylinder
Displacement135 cm 3 (8.2 cu-in)
Max. horsepower4.0 HP (2.9 kW) at 3,600 rpm
Max. torque (crank PTO)8.6 N·m (0.88 kg·m, 6.4 ft·lb) at 2,500 rpm
CarburetorHorizontal type, butterfly valve
Cooling systemForced-air
Ignition systemTransistorized magneto ignition
Lubricating systemSplash
Starting systemRecoil starter
Stoping systemIgnition primary circuit ground
Fuel usedUnleaded gasoline (octane number 86 or higher)
Fuel tank capacity1.7 l (0.45 US. Gal, 0.37 Imp. Gal.)
Fuel consumption230 g/HPh
PTO shaft rotationCounterclockwise (from PTO shaft side)

Dimensions and Weight

SQWVP
Length, mm (in)321 (12.6)330 (13.0)347 (13.7)340 (13.4)330 (13.0)
Width, mm (in)369 (14.5)
Height, mm (in)315 (12.4)
Dry weight, kg (lb)11.2 (24.7)
Operating
weight, kg (lb)
13.0 (28.7)

Cylinder Block and Head

Cylinder block
Compression ratio:8.5:1
Bore x Stroke64 mm X 42 mm (2.5 x 1.7 in)
Sleeve internal diameter64.00 mm (2.52 in)
Piston skirt outer diameter63.969 mm (2.5185 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 gapTop0.20-0.35 mm (0.008-0.014 in)
Second0.30-0.45 mm (0.012-0.018 in)
Oil0.15-0.35 mm (0.006-0.014 in)
Ring widthTop/second1.5 mm (0.06 in)
Oil2.5 mm (0.10 in)
Connecting rod small end ID13.005 mm (0.512 in)
Connecting rod big end ID26.02 mm (1.024 in)
Crankpin outer diameter25.98 mm (1.023 in)
Main journal outer diameterPTO side27.993 mm (1.1021 in)
Flywheel side25.393 mm (0.9997 in)
Cylinder Head
Warpage (limit)0.10 mm (0.004 in)
Valve Arrangement:OHV
Valves:2
Stem outer diameter (standard):INTAKE5.480 mm (0.216 in)
EXHAUST5.44 mm (0.214 in)
Guide internal diameterINTAKE / EXHAUST5.5 mm (0.2165 in)
Spring free length34.0 mm (1.34 in)

Tightening torque specs

Tightening torque specs
Air cleaner case bolt10 Nm; 1.0 kg·m; 7 ft·lb
Crankcase cover bolt12 Nm; 1.2 kg·m; 8.6 ft·lb
Connecting rod bolt12 Nm; 1.2 kg·m; 8.6 ft·lb
Valve adjusting lock nut8 Nm; 0.8 kg·m; 5.8 ft·lb
Cylinder head cover bolt12 Nm; 1.2 kg·m; 8.6 ft·lb
Oil drain plug bolt24 Nm; 2.4 kg·m; 17 ft·lb
Flywheel nut52 Nm; 5.3 kg·m; 38 ft·lb
Governor arm nut10 Nm; 1.0 kg·m; 7 ft·lb
Muffler bolt12 Nm; 1.2 kg·m; 8.6 ft·lb
Recoil starter nut8.5 Nm; 0.85 kg·m; 6.1 ft·lb
Fan cover stud bolt12 Nm; 1.2 kg·m; 8.6 ft·lb
Fuel tank bolt, nut10 Nm; 1.0 kg·m; 7 ft·lb
Spark plug20 Nm; 2.0 kg·m; 14 ft·lb
Others
5 mm bolts, nuts5.5 Nm; 0.55 kg·m; 4.0 ft·lb
6 mm bolts, nuts10 Nm; 1.0 kg·m; 7 ft·lb
8 mm bolts, nuts24 Nm; 2.4 kg·m; 17 ft·lb
10 mm bolts, nuts37 Nm; 3.7 kg·m; 27 ft·lb
12 mm bolts, nuts55 Nm; 5.5 kg·m; 39.5 ft·lb

Service Information

Engine
Maximum speed3,850 ± 150 rpm
Idle speed1,400 ± 150 rpm
Cylinder compression5.0 kg/cm2 (71 psi) at 600 rpm
Valve clearance
Intake valve0.15 ± 0.04 (0.006 ± 0.002)
Exhaust valve0.20 ± 0.04 (0.008 ± 0.002)
Oil system
Oil typeHonda 4-stroke or an equivalent (SE or SF)
Recommended oilSAE 10W-30
Oil capacity0.58 l (0.61 US. qt, 0.55 Imp. qt.)
Ignition system
Ignition timing20° B.T.D.C.
Spark plugNGK: BPR6ES
Spark plug gap0.7-0.8 mm (0.028-0.031 in)
Spark plug torque20 Nm; 2.0 kg·m; 14 ft·lb
Primary ignition coil resistance1.0-1.2 kΩ
Secondary ignition coil resistance10.6-12.8 kΩ
Ignition coil air gap0.2-0.6 mm (0.008-0.024 in)
Carburetor
Main jet#60
Float height9.2 mm (0.36 in)
Pilot screw opening2 turns out
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We try to use verified sources and official documentation, however, differences between sources or errors in entering information may occur. We do not provide advice on technical issues related to the engines operation or repair. We do not recommend using provided information for engines repairing engines or spare parts ordering, use only official service manuals and spare-parts catalogs.

2 Comments

  1. i have an older gc135 to run a water pump i am having a hard time starting it.Is there an on off switch i am missing there is a push/pull next to the pull cord does that have to be in or out. anything else would be appreciated

    • I too have an old GC135, I am not a mechanic and fortunately it starts first pull each time on full choke. There is no on /off switch.

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