The Rato R280 is a 277 cc (16.90 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 Rato R280 engine has an OHV design; flat suction valve carburetor; recoil starter or electric starter, transistorized magneto ignition (TCI) system and centrifugal mechanical governor system.
A 78.0 mm (3.07 in) cylinder bore and 58.0 mm (2.28 in) piston stroke give the Rato R280 motor a total of 277 cc (16.90 cu-in) of displacement. Compression ratio rating is 8.2:1. It produced 10.0 HP of horsepower at 3,600 rpm and 18 N·m (1.83 kg·m, 13.27 ft·lb) of torque at 2,500 rpm.
General information
| Engine Specifications | |
| Model | R280 |
| Type | 4-stroke, OHV, single cylinder |
| Displacement | 277 cm 3 (16.90 cu-in) |
| Max. horsepower | 10.0 HP at 3,600 rpm |
| Max. torque (crank PTO) | 18 N·m (1.83 kg·m, 13.27 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 R280 engine has cast-iron cylinder liner, dual ball bearings and steel forged and hardened crankshaft.
| Cylinder block | ||
| Compression ratio: | 8.2:1 | |
| Bore x Stroke | 78 X 58 mm (3.07 x 2.28 in) | |
| Sleeve internal diameter | 78.000-78.015 mm (3.0708-3.0714 in) | |
| Piston skirt outer diameter | 77.960-76.980 mm (3.0692-3.0700 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 | 0.20-0.60 mm (0.008-0.023 in) |
| Oil | 0.20-0.70 mm (0.008-0.027 in) | |
| Ring width | Top/Second | 3.4-3.6 mm (0.1338-0.1417 in) |
| Oil | 2.75-3.15 mm (0.1082-0.1240 in) | |
| Connecting rod small end ID | 18.211-18.222 mm (0.7169-0.7174 in) | |
| Connecting rod big end ID | 33.225-33.239 mm (1.3080-1.3086 in) | |
| Crankshaft crank pin outer diameter | 33.175-33.185 mm (1.3061-1.3064 in) | |
| Cylinder Head | ||
| Warpage (limit) | 0.10 mm (0.004 in) | |
| Valve Arrangement: | OHV | |
| Valves: | 2 | |
| Stem outer diameter (standard): | INTAKE | 6.575-6.590 mm (0.2589-0.2594 in) |
| EXHAUST | 6.535-6.550 mm (0.2573-0.2579 in) | |
| Cam height: | INTAKE | 6.045 mm (0.2380 in) |
| EXHAUST | 5.766 mm (0.2270 in) | |
| Valve spring free length: | 38.5-39.5 mm (1.5157-1.5551 in) | |
| Camshaft journal diameter: | 16.166-16.184 mm (0.6364-0.6371 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 | 75 Nm; 7.5 kg·m; 55 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
| Engine | |
| Maximum speed | 3750-3850 rpm |
| Cylinder compression | 11.2 kg/cm2 at 1400 rpm |
| Valve clearance | |
| Intake valve clearance | 0.10-0.15 mm (0.004-0.006 in) |
| Exhaust valve clearance | 0.15-0.20 mm (0.006-0.008 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) |
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