The Yamaha MZ250 is a 253 cc (15.4 cu-in) single-cylinder air-cooled 4-stroke internal combustion general-purpose gasoline engine with horizontal shaft manufactured by Yamaha Motor Co., Ltd.
The Yamaha MZ250 engine has an OHV (overhead valve) design; float type carburetor; centrifugal flyweight governor; mechanical splashing lubrication system; Transistor Controlled Ignition (T.C.I.) and recoil or electrical (option) starter. The Yamaha MZ250 used aluminum cylinder block with a spiny cast-iron sleeve. For exhaust valve used high heat resistant SUH3 steel.
The cylinder bore is 74.0 mm (2.91 in) and the piston stroke is 59.0 mm (2.32 in), compression ratio rating is 8.7:1. The engine produced 7.3 PS (5.4 kW) at 3,600 rpm of maximum horsepower and 6.1 PS (4.5 kW) at 3,600 rpm of continuous rated power. Maximum torque is 15.7 N·m (1.60 kg·m, 11.6 ft·lb) at 2,400 rpm.
General information
| Engine Specifications | |
| Model | MZ250 |
| Type | 4-stroke, OHV, single cylinder |
| Displacement | 253 cm 3 (15.4 cu-in) |
| Max. horsepower | 7.3 PS (5.4 kW) at 3,600 rpm |
| Max. torque (crank PTO) | 15.7 N·m (1.60 kg·m, 11.6 ft·lb) at 2,400 rpm |
| Carburetor | Float type |
| Cooling system | Forced-air |
| Ignition system | Transistor Controlled Ignition (T.C.I.) |
| Lubricating system | Mechanical splashing |
| Starting system | Recoil or Electrical (option) |
| Fuel used | Unleaded gasoline (octane number 86 or higher) |
| Fuel tank capacity | 5.5 L (1.45 US Gal, 1.21 Imp Gal.) |
| PTO shaft rotation | Counterclockwise (from PTO shaft side) |
Dimensions and Weight
| Yamaha MZ250 | |
| Length, mm (in) | 362 (14.2) |
| Width, mm (in) | 426 (16.7) |
| Height, mm (in) | 427 (16.8) |
| Dry weight, kg (lb) | 26.0 (57.3) |
Service Information
| Valve clearance | |
| Intake valve clearance | 0.10 mm (0.004 in) |
| Exhaust valve clearance | 0.10 mm (0.004 in) |
| Oil system | |
| Oil type | Yamalube 4-stroke or an equivalent (SE or SF) |
| Recommended oil | SAE 10W-30, 10W-40 |
| Oil capacity | 1.0 L (1.06 US. qt, 0.88 Imp. qt.) |
| Ignition system | |
| Spark plug | NGK: BPR4ES |
| Spark plug gap | 0.7-0.8 mm (0.028-0.031 in) |
| T.C.I. air gap | 0.4 ± 0.2 (0.016 ± 0.008) |
| Spark plug tightening torque | 20 N·m (2.0 kg·m, 14 ft·lb) |
How much is it…it is highspeed engine?