Yamaha MZ250

Yamaha MZ250The 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)
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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