Yamaha MZ300

Yamaha MZ300The Yamaha MZ300 is a 296 cc (18.0 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 MZ300 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 MZ300 used aluminum cylinder block with a spiny cast-iron sleeve. For exhaust valve used high heat resistant SUH3 steel.

The cylinder bore is 80.0 mm (3.15 in) and the piston stroke is 59.0 mm (2.32 in), compression ratio rating is 8.4:1. The engine produced 9.5 PS (7.0 kW) at 3,600 rpm of maximum horsepower and 7.9 PS (5.8 kW) at 3,600 rpm of continuous rated power. Maximum torque is 20.3 N·m (2.07 kg·m, 14.97 ft·lb) at 2,400 rpm of torque.

General information

Engine Specifications
Model MZ300
Type 4-stroke, Hemi-head OHV, single cylinder
Displacement 296 cm 3 (18.0 cu-in)
Max. horsepower 9.5 PS (7.0 kW) at 3,600 rpm
Max. torque (crank PTO) 20.3 N·m (2.07 kg·m, 14.97 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 MZ300
Length, mm (in) 362 (16.2)
Width, mm (in) 426 (16.7)
Height, mm (in) 426 (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)
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1 Comment

  1. I have a question I’m hoping you can answer. Is it possible to put a mz300 generator engine onto a ys624 snowblower? Is there a difference in the crankshaft ends? I know it i has more h.p. but is it the only difference? Thanks

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