The 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 MX800V-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 MX800V-EFI produces 31.6 PS (23.6 kW) at 3,600 rpm of maximum gross power or 31.0 HP (23.1 kW) at 3,600 rpm of gross rated power (SAE J1995) and 65.3 Nm (6.66 kg·m, 48.2 ft·lb) at 3,100 rpm of torque.
|Type||4-stroke, OHV, V-twin|
|Displacement||824 cm 3 (50.3 cu-in)|
|Max. horsepower||31.6 PS (23.6 kW) at 3,600 rpm|
|Max. torque (crank PTO)||65.3 Nm (6.66 kg·m, 48.2 ft·lb) at 3,100 rpm|
|Fuel system||Delphi Multec – EFI|
|Ignition system||ECU Controlled Electronic Ignition Coils|
|Lubricating system||Full pressure with filter|
|Starting system||Electric starter|
|Fuel used||Unleaded gasoline (octane number 86 or higher)|
|Fuel tank capacity||–|
|PTO shaft rotation||Counterclockwise (from PTO shaft side)|
|Maximum speed||3550-3600 rpm|
|Cylinder compression||13.4-14.8 kg/cm2 (190-210 psi)|
|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 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 timing||BTDC 30° / 3750 rpm|
|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)
|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)|
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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