Segment:
Entry-level to intermediate youth motocross competition.
Competitors:
KTM 85 SX, Honda CR85R, Suzuki RM85, Kawasaki KX85.
Yz85 Strengths:
Lightweight, nimble handling, strong low-to-mid range power, reliable engine, accessible maintenance.
Design Philosophy:
Yamaha's commitment to performance and durability in youth motocross racing.
Manual Value Proposition:
Empowers owners and technicians with the knowledge to maintain and repair the YZ85 effectively, maximizing performance and lifespan.
Engine:
Complete overhaul, diagnosis, tuning, fuel system, ignition system, cooling system, lubrication system.
Transmission:
Clutch, gearbox, drive chain maintenance, lubrication.
Chassis Suspension:
Front fork (KYB Speed Sensitive System), rear shock absorber (Monocross), linkage system, wheel bearings, swingarm.
Brakes:
Front and rear hydraulic disc brake systems, caliper, master cylinder, brake fluid specifications, bleeding procedures.
Electrical:
Ignition system, lighting, wiring diagrams, battery maintenance, troubleshooting.
Bodywork Frame:
Frame inspection, plastic components, seat, handlebars, footpegs.
Maintenance:
Scheduled maintenance, oil changes, filter replacements, chain adjustment, spark plug replacement, air filter cleaning.
Troubleshooting:
Diagnostic charts, common problems and their solutions, electrical system troubleshooting.
Repair:
Engine rebuilds, carburetor tuning, suspension servicing, brake system repairs, electrical component replacement.
Disassembly Assembly:
Detailed step-by-step instructions for component removal and installation.
Depth:
Comprehensive: Covers basic maintenance to full engine and chassis overhauls with detailed specifications.
Diagnostics:
Advanced diagnostic procedures for engine performance and electrical systems.
Type:
Liquid-cooled, 2-stroke, reed valve induction
Bore X Stroke:
47.5 mm x 47.8 mm
Compression Ratio:
8.6:1 (for 2004)
Horsepower:
Approx. 17.2 HP @ 11,000 RPM (Estimated)
Torque:
Approx. 7.1 lb-ft @ 10,000 RPM (Estimated)
Fuel Type:
Unleaded gasoline (91 octane or higher recommended)
Fuel Oil Mixture:
50:1 ratio (Yamalube 2-stroke oil or equivalent)
Carburetor Jetting:
Detailed jetting specifications and adjustments covered in manual.
Safety Standards:
Not applicable for competition off-road vehicles; focus on rider protection.
Brakes:
Powerful hydraulic disc brakes for effective stopping power.
Suspension:
Performance-tuned suspension for stability and control during jumps and cornering.
Chassis Design:
Robust frame designed to withstand the rigors of motocross.
Ergonomics:
Rider-centric design for optimal control and reduced fatigue.
Oil Change Frequency:
Every 10-15 hours of riding or annually, whichever comes first. Manual specifies exact procedure.
Air Filter Cleaning:
After every few rides, or as dictated by conditions. Detailed cleaning and oiling instructions provided.
Spark Plug Replacement:
Recommended every 25-30 hours of riding. Manual specifies correct plug type and gap.
Chain Lubrication Adjustment:
Before every ride for lubrication, adjustment as needed. Manual provides precise slack specifications.
Top End Rebuild:
Recommended between 50-70 hours of riding, depending on usage. Manual details piston, ring, and cylinder inspection and replacement.
Engine Oil:
Yamalube 2-stroke injector oil (for oil injection models) or specific 2T premix oil. Manual specifies 50:1 ratio.
Transmission Oil:
Yamaha Gear Oil Hypoid 80W-90 or equivalent. Manual specifies capacity and inspection method.
Coolant:
High-quality coolant mixed with distilled water (50/50 ratio). Manual specifies type and capacity.
Brake Fluid:
DOT 4 hydraulic brake fluid. Manual details replacement interval and bleeding procedure.
Common Wear Items:
Clutch plates, piston rings, chain and sprockets, brake pads, wheel bearings.
Performance Tips:
Carburetor jetting optimization for altitude and temperature, proper jetting for optimal performance and engine longevity.
Yamaha Legacy:
Yamaha's long-standing history in motocross, dating back to the early days of the sport, with iconic models like the YZ series.
Yz85 Development:
The YZ85 has been a staple in the youth motocross class, consistently refined for performance and handling. The 2004-2005 models represent a significant iteration in its development.
Manufacturing Location:
Japan
