Rato R440

Rato R440The Rato R440 is a 440 cc (26.85 cu-in) single-cylinder air-cooled 4-stroke internal combustion general-purpose gasoline engine with horizontal shaft manufactured by Chongqing RATO Holding (Group) CO., LTD.

The R440 engine has an (OHV) overhead-valve design; flat suction valve carburetor; recoil starter or electric starter, transistorized magneto ignition (TCI) system and centrifugal mechanical governor system.

The Rato R440 motor has a 92.0 mm (3.62 in) cylinder bore and 66.0 mm (2.60 in) piston stroke with a compression ratio of 8.5:1. It produced 16.0 HP of horsepower at 3,600 rpm and 27 N·m (2.75 kg·m, 19.9 ft·lb) at 2,500 rpm of torque.

General information

Engine Specifications
Model R440
Type 4-stroke, OHV, single cylinder
Displacement 440 cm 3 (26.85 cu-in)
Max. horsepower 15.0 HP at 3,600 rpm
Max. torque (crank PTO) 27 N·m (2.75 kg·m, 19.9 ft·lb) at 2,500 rpm
Carburetor Flat suction valve carburetor
Cooling system Forced-air
Ignition system Transistorized magneto ignition (TCI)
Lubricating system Splash
Starting system Recoil / electric starter
Stoping system Ignition primary circuit ground
Fuel used Unleaded gasoline (octane number 86 or higher)
PTO shaft rotation Counterclockwise (from PTO shaft side)

Cylinder Block and Head

The Rato R440 engine has cast-iron cylinder liner, dual ball bearings and steel forged and hardened crankshaft.

Cylinder block
Compression ratio: 8.5:1
Bore x Stroke 92 X 66 mm (3.62 x 2.60 in)
Sleeve internal diameter 92.000-92.015 mm (3.6220-3.6226 in)
Piston skirt outer diameter 91.960-91.970 mm (3.6204-3.6208 in)
Number of piston rings (compression / oil): 2 / 1
Ring side clearance Top/Second 0.020-0.060 mm (0.0008-0.0023 in)
Ring end gap Top/Second 0.20-0.40 mm (0.008-0.016 in)
Oil 0.20-0.70 mm (0.008-0.027 in)
Connecting rod small end ID 20.011 mm (0.7878 in)
Connecting rod big end ID 36.025 mm (1.4183 in)
Crankshaft crank pin outer diameter 35.985 mm (1.4167 in)
Cylinder Head
Warpage (limit) 0.10 mm (0.004 in)
Valve Arrangement: OHV
Valves: 2
Stem outer diameter (standard): INTAKE 5.490 mm (0.2161 in)
EXHAUST 5.450 mm (0.2146 in)
Cam height: INTAKE 32.742-33.142 mm (1.2890-1.3048 in)
EXHAUST 31.609-32.009 mm (1.2444-1.2601 in)
Valve spring free length: 39.0 mm (1.5354 in)
Camshaft journal diameter: 15.984 mm (0.6293 in)

Tightening torque specs

Tightening torque specs
Connecting rod bolt 15 Nm; 1.5 kg·m; 11 ft·lb
Oil dran plug 22 Nm; 2.2 kg·m; 16 ft·lb
Crankcase cover 28 Nm; 2.8 kg·m; 21 ft·lb
Flywheel subassembly 95 Nm; 9.5 kg·m; 70 ft·lb
Cylinder head subassembly 42 Nm; 4.2 kg·m; 31 ft·lb
Rocker shaft bolt 24 Nm; 2.4 kg·m; 18 ft·lb
Cylinder head cover 10 Nm; 1.0 kg·m; 7 ft·lb
Spark plug 28 Nm; 2.8 kg·m; 21 ft·lb
Ignition coil 10 Nm; 1.0 kg·m; 7 ft·lb

Service Information

Maximum speed 3750-3810 rpm
Cylinder compression 12.2 kg/cm2 at 1400 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
Oil type 4-stroke or an equivalent (SJ)
Recommended oil SAE 10W-30, 15W-40
Oil capacity 1.1 L
Ignition system
Spark plug NGK: BPR6ES
Spark plug gap 0.7-0.8 mm (0.028-0.031 in)
Primary ignition coil resistance 0.6-0.9 Ω
Secondary ignition coil resistance 5.6-6.9 kΩ
Ignition coil air gap 0.4 ± 0.2 (0.016 ± 0.008)
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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