Yamaha MX825V-EFI

Yamaha MX825V-EFIThe Yamaha MX800V-EFI 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-EFI 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; electronic fuel injected system (Delphi Multec-EFI); ECU controlled electronic ignition coils and an 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 9.1:1. The MX825V-EFI produces 33.8 PS (25.2 kW) at 3,600 rpm of maximum gross power or 33.0 HP (24.6 kW) at 3,600 rpm of gross rated power (SAE J1995) and 67.9 Nm (6.92 kg·m, 50.1 ft·lb) at 3,100 rpm of torque.

General information

Engine Specifications
Type4-stroke, OHV, V-twin
Displacement824 cm 3 (50.3 cu-in)
Max. horsepower33.8 PS (25.2 kW) at 3,600 rpm
Max. torque (crank PTO)67.9 Nm (6.92 kg·m, 50.1 ft·lb) at 3,100 rpm
Fuel systemDelphi Multec – EFI
Cooling systemForced-air
Ignition systemECU Controlled Electronic Ignition Coils
Lubricating systemFull pressure with filter
Starting systemElectric starter
Stoping systemMisfire
Fuel usedUnleaded gasoline (octane number 86 or higher)
Fuel tank capacity
Fuel consumption
PTO shaft rotationCounterclockwise (from PTO shaft side)

Service Information

Maximum speed3550-3600 rpm
Cylinder compression13.4-14.8 kg/cm2 (190-210 psi)
Valve clearance
Intake valve0.07-0.13 mm (0.003-0.005 in)
Exhaust valve0.07-0.13 mm (0.003-0.005 in)
Oil system
Oil typeYamalube 4-stroke or an equivalent (SE or higher)
Recommended oilSAE 10W-30
Oil capacity2.0 L (2.11 US qt, 1.76 Imp.qt)
Ignition system
Ignition timingBTDC 30° / 3750 rpm
Spark plugNGK: BPR6ES
Spark plug gap0.7-0.8 mm (0.028-0.031 in)
Spark plug tightening torque20 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 bolt4.0 Nm (0.40 kg·m, 2.9 lb·ft)
Cylinder head cover bolt11.0 N·m (1.1 kg·m, 8.0 lb·ft)
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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