Motorcycle Segment:
Entry-level to intermediate motocross racing motorcycle.
Target Audience:
Junior motocross riders, aspiring racers, and enthusiasts.
Key Competitors:
KTM 85 SX, Suzuki RM85, Kawasaki KX85, Honda CR85.
Yz85 Strengths:
Renowned for its potent two-stroke engine, agile handling, and robust suspension for its class.
Manual Value Proposition:
Provides essential knowledge for owners and mechanics to maintain peak performance and longevity of the YZ85.
Engine:
Complete overhaul, top-end, bottom-end, lubrication, cooling, fuel delivery, exhaust.
Transmission:
Clutch, gearbox, shift mechanism, lubrication, troubleshooting.
Chassis Suspension:
Front fork (USD telescopic damping), rear shock absorber, swingarm, linkage system, bearings.
Brakes:
Front and rear hydraulic disc brakes, caliper overhaul, master cylinder, bleeding procedures.
Electrical System:
Ignition system, CDI unit, lighting (if applicable), wiring diagrams, troubleshooting.
Fuel System:
Carburetor (Keihin PWK38S typically), jetting, float adjustment, fuel lines, tank.
Cooling System:
Water-cooled system, radiator, water pump, thermostat (if applicable).
Exhaust System:
Expansion chamber, silencer, packing replacement.
Wheels Tires:
Wheel bearing maintenance, spoke tensioning, tire fitting, rim maintenance.
Controls:
Throttle, clutch lever, brake lever, footpegs, handlebar setup.
Bodywork:
Plastic panels, seat, tank cover, fender replacement.
Diagnostic Procedures:
Troubleshooting charts for common issues, fault finding.
Maintenance Tasks:
Regular service, lubrication points, filter changes, bolt torques.
Repair Procedures:
Step-by-step instructions for all major components.
Rebuild Procedures:
Detailed engine and transmission rebuild instructions.
Disassembly Reassembly:
Complete instructions for taking apart and putting back together the entire motorcycle.
Depth Of Coverage:
Comprehensive from basic checks to complete engine and transmission rebuilds.
Diagnostic Level:
Advanced diagnostic information and troubleshooting guides.
Special Tool Requirements:
Details on required special tools for specific tasks.
Engine Type:
Liquid-cooled, 2-stroke, reed valve, YPVS (Yamaha Power Valve System)
Bore X Stroke:
47.5 mm x 47.2 mm
Compression Ratio:
9.3:1 (typical, may vary slightly)
Horsepower:
Approx. 16.5 - 17.5 HP @ 12,500 RPM (estimated, specific dyno results vary)
Torque:
Approx. 7.0 - 7.5 lb-ft @ 11,000 RPM (estimated)
Carburetor Model:
Keihin PWK38S (38mm slide valve with Power Jet)
Fuel Type:
Unleaded gasoline (91 octane or higher recommended)
Premix Ratio:
50:1 (Yamaha recommends specific 2-stroke oil, e.g., Yamalube 2R)
Ignition System:
Digital CDI
Cooling Method:
Liquid-cooled
Transmission Type:
6-speed constant mesh
Clutch Type:
Wet, multi-plate, cable-actuated
Gear Ratios:
Detailed in manual, specific ratios for each gear.
Final Drive:
Chain drive (typically 428 pitch)
Transmission Oil Capacity:
Approximately 0.6 L (for gearbox, separate from 2-stroke oil)
Transmission Oil Type:
Yamalube Gear Oil (or equivalent motorcycle transmission oil)
Length:
Approx. 1830 mm (72.0 in)
Width:
Approx. 770 mm (30.3 in)
Height:
Approx. 1165 mm (45.9 in)
Wheelbase:
Approx. 1250 mm (49.2 in)
Ground Clearance:
Approx. 320 mm (12.6 in)
Seat Height:
Approx. 850 mm (33.5 in)
Wet Weight:
Approx. 77 kg (169.8 lbs) (fully fueled, ready to ride)
Dry Weight:
Approx. 71 kg (156.5 lbs)
Oil Change Transmission:
Every 10-15 hours of riding or annually. Check manual for precise intervals.
Air Filter Cleaning:
After every few rides, especially in dusty conditions.
Spark Plug Replacement:
Refer to manual; typically every 20-30 hours or as needed based on performance.
Top End Rebuild:
Recommended every 40-60 hours of hard riding or based on compression testing.
Suspension Service:
Fork seal replacement and oil change every 20-30 hours; shock service as needed or annually.
Engine Oil Type:
High-quality 2-stroke motorcycle oil (e.g., Yamalube 2R, Motul 800 2T Off Road)
Coolant Type:
High-quality motorcycle-specific antifreeze coolant (50/50 mix with distilled water recommended).
Brake Fluid Type:
DOT 4 hydraulic brake fluid.
Common Wear Items:
Clutch plates, piston rings, spark plugs, chain and sprockets, wheel bearings, suspension seals.
Carburetor Tuning Sensitivity:
Two-stroke engines, especially with YPVS, can be sensitive to jetting changes and altitude; requires meticulous tuning.
Ypvs Maintenance:
The Yamaha Power Valve System requires regular cleaning and inspection to ensure proper operation and prevent carbon buildup.
Yamaha Motorsports Legacy:
Yamaha has a long and storied history in motocross and off-road racing, consistently producing competitive machinery.
Yz85 Development:
The YZ85 is a direct descendant of Yamaha's championship-winning YZ racing lineage, focusing on performance and handling for young riders.
Manufacturing Location:
Primarily manufactured in Japan.
