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Yamaha MX250 Engine

General Technical Data

Yamaha MX250 Engine Specifications

Engine Model ................ Yamaha MX250
Engine Type ................ 4-cycle hemi-head overhead valve 1-cylinder air-cooled gasoline engine
Number of Cylinders ................ Single
Displacement, cu.in (cc) ................ 18.1 (296)
Cylinder Bore, in (mm) ................ 3.15 (80.0)
Piston Stroke, in (mm) ................ 2.32 (59.0)
Rated Engine Power, hp (kW) ................ 8.7 (6.4)
Rated Engine Speed, rpm ................ 3600
Maximum Torque, Nm (ft-lbs) ................ 19.7 (14.5)
Torque Speed, rpm ................ 2400
Compression Ratio ................ 8.4:1
Valve Arrangement ................ OHV
PTO Shaft Rotation ................ Counterclockwise (from PTO shaft side)
Lubrication System ................ Forced splash type
Cooling System ................ Forced air
Ignition System ................ TCI (transistor controlled ignition)
Starting System ................ Recoil or electric starter

Fuel System

Fuel System Type ................ Carburetor
Carburetor Type ................ Float
Governor Type ................ Centrifugal, flyweight
Fuel Tank Capacity, qts (L) ................ 5.8 (5.5)
Fuel Type ................ Gasoline (86 or higher)

Dimensions and Weight

Overall Length, in (mm) ................ 15.4 (390)
Overall Width, in (mm) ................ 17.5 (444)
Overall Height, in (mm) ................ 17.8 (451)
Dry Weight, lbs (kg) ................ 58.3 (26.5)

Yamaha MX250 Maintenance Data

Service Data

Cylinder Bore Inside Diameter (Max), in (mm) ................ 3.1561 (80.165)
Cylinder Head (Max. Out of Flatness), in (mm) ................ 0.003 (0.08)
Intake Valve Clearance, in (mm) ................ 0.004 (0.10)
Exhaust Valve Clearance, in (mm) ................ 0.004 (0.10)

Engine Oil and Filter

Engine Oil Type ................ Yamalube, SAE 10W, SAE 10W-30, 10W-40
API Service Classifications ................ SE or SF
Oil Capacity, qts (L) ................ 1.06 (1.00)
Air Filter Element Part Number ................ 7VE-E4450-00

Ignition System

Spark Plug Type ................ NGK BPR4ES
Spark Plug Gap, in (mm) ................ 0.028-0.032 (0.70-0.80)
TCI Air Gap, in (mm) ................ 0.008-0.024 (0.20-0.60)
Spark Plug Torque, Nm (ft-lbs) ................ 20 (14)

Service Intervals

Check Engine Oil Level ................ Every 10 hours
Service Air Filter Element ................ Every 50 hours
Clean and Adjust Spark Plug ................ Every 50 hours
Change Engine Oil ................ Every 100 hours
Clean Fuel Filter ................ Every 100 hours
Check Fuel Hose ................ Every 100 hours
Replace Spark Plug ................ Every 150 hours
Replace Air Filter Element ................ Every 200 hours
Check Carburetor Adjustment ................ Every 200 hours
Check and Adjust Idle Speed ................ Every 300 hours
Check and Adjust Valve Clearance ................ Every 300 hours

Replacement Parts

Cylinder Head Gasket. Part Number ................ 7VB-E1181-01
Head Cover Gasket. Part Number ................ 7VB-E1193-01
Crankshaft Oil Seal. Part Number ................ 93102-30801
Spark Plug. Part Number ................ 94702-00331
Fuel Strainer. Part Number ................ 7CN-F4167-00
Air Filter Element. Part Number ................ VE-E4450-00
Air Filter Gasket. Part Number ................ 7HC-E4457-00