Yamaha MX825V

Yamaha MX825VThe Yamaha MX825V is a small (824 cc, 50.3 cu-in) V-twin air-cooled four-stroke internal combustion gasoline engine with vertical shaft, manufactured by Yamaha.

The Yamaha MX825V motor has two-cylinder, overhead valves and a ball bearing supported P.T.O. The engine is equipped with an industry-standard air filtration system; float-type carburetor; T.C.I. ignition system and electric starter.

The cylinder bore and the piston stroke is 80.0 mm (3.15 in) and 82.0 mm (3.23 in), respectively. The compression ratio rating is 8.6:1. The MX825V produces 27.8 HP (20.7 kW) at 3,600 rpm of maximum gross power or 27.5 HP (20.5 kW) at 3,600 rpm of gross rated power (SAE J1995) and 63.2 Nm (6.44 kg·m, 46.6 ft·lb) at 3,100 rpm of torque.

General information

Engine Specifications
Model MX825V
Type 4-stroke, OHV, V-twin
Displacement 824 cm 3 (50.3 cu-in)
Max. horsepower 27.8 HP (20.7 kW) at 3,600 rpm
Max. torque (crank PTO) 63.2 Nm (6.44 kg·m, 46.6 ft·lb) at 2,200 rpm
Fuel system Float-type carburetor
Cooling system Forced-air
Ignition system T.C.I. ignition
Lubricating system Full pressure with filter
Starting system Electric starter
Stoping system Misfire
Fuel used Unleaded gasoline (octane number 86 or higher)
Fuel tank capacity
Fuel consumption
PTO shaft rotation Counterclockwise (from PTO shaft side)

Service Information

Maximum speed 3550-3600 rpm
Cylinder compression 13.4-14.8 kg/cm2 (190-210 psi)
Valve clearance
Intake valve 0.07-0.13 mm (0.003-0.005 in)
Exhaust valve 0.07-0.13 mm (0.003-0.005 in)
Oil system
Oil type Yamalube 4-stroke or an equivalent (SE or higher)
Recommended oil SAE 10W-30
Oil capacity 2.0 L (2.11 US qt, 1.76 Imp.qt)
Ignition system
Spark plug NGK: BPR6ES
Spark plug gap 0.7-0.8 mm (0.028-0.031 in)
Spark plug tightening torque 20 N·m (2.0 kg·m, 14 ft·lb)

Valve clearance adjustment data

Calculate the thickness of new adjusting pad so valve clearance comes within specified values.

R = Thickness of removed adjusting pad
N = Thickness of new adjusting pad
M = Measured valve clearance

N = R + [M – 0.13 mm (0.005 in)]

Adjusting pads are available from 1.80 mm (0.0708 in) to 3.00 mm (0.1181 in), in steps of 0.05 mm (0.002 in).

R = 1.80 mm
M = 0.22 mm
N = 1.80 + (0.22 – 0.13) = 1.89 mm, round to 1.90 mm, so we need a adjusting pad with code 190.

Adjust valve celarance at 1000 hr periodic maintenance, normal operational range between periodic maintenance may be 0.02-0.2 mm (0.0008-0.01 in)

Tightening torque
Rocker arm shaft bolt 4.0 Nm (0.40 kg·m, 2.9 lb·ft)
Cylinder head cover bolt 11.0 N·m (1.1 kg·m, 8.0 lb·ft)
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We try to use verified sources and official documentation, however, differences between sources or errors in entering information may occur. We do not provide advice on technical issues related to the engines operation or repair. We do not recommend using provided information for engines repairing engines or spare parts ordering, use only official service manuals and spare-parts catalogs.

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