Category:
Motocross / Off-Road Performance Motorcycle
Era:
80s Performance Era Motocross
Competitors:
Suzuki RM490, Honda CR480R/CR500R, Kawasaki KX420/KX500
Engine Type:
Powerful Two-Stroke Single-Cylinder
Suspension:
Advanced Monocross Rear Suspension System
Design Philosophy:
Dominance in Open Class Motocross Competition
Primary Coverage:
Complete Service, Repair, and Workshop Information
Secondary Coverage:
Maintenance, Troubleshooting, Diagnostics, Overhaul
Estimated Pages:
N/A (Digital Download - Comprehensive)
Type:
Service Repair Workshop Manual
Format:
Digital Download (PDF)
Engine:
Top End, Bottom End, Lubrication, Cooling (Air), Fuel System, Ignition System, Exhaust System
Transmission:
Clutch, Gearbox Internals, Shift Mechanism, Final Drive (Chain)
Chassis:
Frame, Front Suspension (Telescopic Forks), Rear Suspension (Monoshock - Monocross), Swingarm, Steering System
Brakes:
Front Disc Brake System, Rear Drum Brake System, Hydraulic Lines, Master Cylinders, Calipers
Electrical:
Wiring Harness, Lighting (Headlight, Taillight, Indicators), Ignition Coil, CDI Unit, Spark Plug, Battery Charging System
Bodywork:
Fuel Tank, Seat, Fenders, Handlebars, Controls
Maintenance:
Routine Checks, Lubrication Points, Filter Replacements, Spark Plug Service, Chain Adjustment
Repair:
Engine Overhaul, Transmission Rebuild, Suspension Servicing, Brake System Repairs, Carburetor Rebuild
Troubleshooting:
Diagnostic Charts for Common Performance Issues, Electrical Fault Finding
Diagnostics:
Component Testing, Specification Checks
Depth:
Comprehensive - from basic adjustments to complete engine and gearbox rebuilds
Engine Type:
Air-Cooled, 2-Stroke, Reed Valve, Single-Cylinder
Displacement:
485cc (29.6 cu in)
Bore X Stroke:
84.0 mm x 87.0 mm (3.31 in x 3.43 in)
Carburetor:
Mikuni VM38SS (38mm Constant Velocity)
Ignition:
CDI (Capacitor Discharge Ignition)
Horsepower Estimated:
Approx. 50-55 HP (Source: Performance magazines of the era)
Torque Estimated:
N/A (Data not commonly published for MX bikes of this era)
Fuel Type:
Unleaded Gasoline with 2-Stroke Oil Mixture (e.g., 40:1)
Fuel Tank Capacity:
8.0 L (2.1 US gal)
Oil Change:
Every 10-15 hours of riding, or annually (refer to manual for specific recommendations)
Air Filter Cleaning:
After every few rides or when visibly dirty (depending on conditions)
Spark Plug Service:
Every 20-30 hours of riding (or as needed based on condition)
Chain Adjustment Lubrication:
Every 5-10 hours of riding
Top End Rebuild:
Highly dependent on riding style and conditions; typically every 40-80 hours for competitive use.
Engine Oil Type:
2-Stroke Premix Oil (e.g., Yamalube 2R, Castrol TTS) at 40:1 ratio (confirm in manual)
Transmission Oil Type:
Yamaha recommended gear oil or equivalent API GL-4 (e.g., Yamalube Gear Oil 10W-30 or 80W-90) - 0.8 L capacity (refer to manual)
Fork Oil Type:
Yamaha Genuine Fork Oil or equivalent (e.g., Showa SS-8, Bel-Ray High-Performance Suspension Fluid) - Viscosity and level specified in manual (typically around 10W)
Engine Power Delivery:
Known for being very powerful, sometimes described as 'hard-hitting' or difficult to manage for less experienced riders. Carburetor tuning critical.
Clutch:
Can wear under heavy use; proper adjustment and replacement of plates/springs are crucial.
Suspension:
While advanced for its time, original suspension components may require servicing or upgrades for modern riding standards.
Durability:
As with many high-performance 2-strokes of this era, diligent maintenance is key to ensuring longevity.
Parent Company:
Yamaha Motor Company
Motorsport Focus:
Yamaha has a long and successful history in motorcycle racing across various disciplines, including motocross.
Yz Lineage:
The YZ series represents Yamaha's flagship motocross machines, constantly evolving with technological advancements.
Yz490 Development:
The YZ490 was Yamaha's entry into the highly competitive Open Class motocross category, evolving from earlier 400cc and 465cc models, aiming for increased power and refinement.
Production Years:
The YZ490 model line generally ran from the early 1980s through the late 1980s, with the 1986 model being a specific iteration.
Manufacturing Location:
Japan
Motocross Contributions:
The YZ490 was a significant contender in the Open Class motocross scene during its production years, known for its raw power and competitive spirit.
Contemporaneous Reviews:
Often praised for its torque and power, but also noted for its demanding nature and the need for skilled rider input.
Certification:
N/A (Not applicable for this vehicle type)
