🏷️ Basic Information

Make:

Yamaha

Model:

YZ85

Model Variant:

YZ85LW (Large Wheel)

Model Year:

2005

Product Type:

Service Manual / Repair Manual

Oem Part Number Manual:

Not specified in product information (typically found on manual cover or inside)

👋 Introduction

Segment:

Youth Motocross / Off-road Competition

Purpose:

Designed for competitive youth riders looking for performance and handling in the 85cc class.

Key Competitors:

KTM 85 SX, Suzuki RM85, Kawasaki KX85, Honda CR85R.

Yz85 Advantage:

Yamaha's YZ85 typically known for its strong engine performance, advanced suspension technology (Kayaba), and durable construction, appealing to serious young racers.

Engine Type:

Liquid-cooled, 2-stroke, reed valve induction

Suspension Front:

Upside-down telescopic fork (Kayaba)

Suspension Rear:

Monocross suspension with Kayaba shock absorber

Wheelbase Lw Variant:

Longer wheelbase for improved stability in the LW (Large Wheel) model.

📋 Manual Details

General Coverage:

Complete tear down and rebuild, maintenance, troubleshooting, electrical diagnostics, chassis, engine, transmission, suspension, wheels, brakes, bodywork.

Specific Models Covered:

2005 Yamaha YZ85, 2005 Yamaha YZ85LW

Estimated Page Count:

Typically 300-500 pages for this type of comprehensive service manual. Actual count not provided in product info.

Manual Type:

Factory Service Manual

Language:

English

Format:

Digital Download (PDF)

📖 Manual Coverage

Engine:

Complete engine overhaul, top-end rebuild, bottom-end assembly, carburetor tuning and overhaul, cooling system (if applicable, though YZ85 is air-cooled), lubrication system.

Transmission:

Clutch operation and service, gearbox disassembly and reassembly, shift mechanism.

Electrical:

Ignition system, lighting (if applicable), wiring diagrams, component testing, troubleshooting.

Chassis:

Frame inspection and repair, suspension (forks, rear shock), steering system, swingarm, subframe.

Brakes:

Front and rear brake systems, hydraulic lines, caliper service, master cylinder overhaul, bleeding procedures.

Wheels And Tires:

Spoke tensioning, wheel bearing replacement, tire mounting and balancing.

Maintenance:

Pre-ride inspection checklist, routine service intervals, oil changes, filter cleaning/replacement, chain adjustment, spark plug replacement, brake pad inspection.

Repair:

Complete engine rebuild, suspension fork seal replacement, carburetor jetting and cleaning, clutch plate replacement, wheel bearing service.

Troubleshooting:

Diagnostic procedures for common performance issues, starting problems, electrical faults, and mechanical noises.

Diagnostics:

Systematic troubleshooting guides based on symptoms, electrical continuity testing, compression testing.

Depth:

Comprehensive. Covers everything from basic maintenance to full engine and chassis tear-down and rebuild. Includes detailed diagrams and torque specifications for critical fasteners.

📊 Manual Specifications

File Format:

PDF

Searchable:

Likely searchable if digitally created/scanned with OCR, but not guaranteed without direct inspection.

Print Quality:

Digital; printing quality depends on user's printer. Factory manuals are typically black and white with clear line drawings and photographs.

Binding Type:

N/A (Digital Download)

Paper Type:

N/A (Digital Download)

⚙️ Engine Specifications

Engine Type:

Liquid-cooled, 2-stroke, single-cylinder

Displacement:

84.7 cc

Bore X Stroke:

47.5 mm x 47.8 mm

Compression Ratio:

8.8:1 (at 6.1 kPa / 0.061 bar with 0.8 mm Gk.)

Carburetor:

Keihin PWK28 (28mm slide valve, VM-type)

Ignition:

CDI (Capacitor Discharge Ignition)

Horsepower Estimated:

Approx. 21.5 - 23 hp at ~12,000 rpm (OEM specification not always published; industry estimates)

Torque Estimated:

Approx. 11.5 - 12.5 Nm at ~11,000 rpm (OEM specification not always published; industry estimates)

Fuel Type:

Unleaded gasoline (min. 91 octane recommended)

Fuel Tank Capacity:

5.4 Liters (1.4 US gal)

Oil Mixing Ratio:

2-stroke engine oil mixed with gasoline at 50:1 ratio. Yamaha recommends Yamalube 2R or equivalent.

🔧 Transmission

Transmission Type:

Constant-mesh 6-speed

Clutch:

Wet, multiple-disc, cable-actuated

Gear Ratios:

1st: 2.500, 2nd: 1.833, 3rd: 1.400, 4th: 1.136, 5th: 0.913, 6th: 0.750

Final Drive:

Chain drive

Transmission Oil Type:

Yamalube 10W-40 API SG SAE 10W-40 or equivalent. Capacity: 0.63 Liters (0.66 US qt)

📐 Dimensions

Overall Length:

1840 mm (72.4 in) for YZ85; 1880 mm (74.0 in) for YZ85LW

Overall Width:

780 mm (30.7 in)

Overall Height:

1145 mm (45.1 in) for YZ85; 1155 mm (45.5 in) for YZ85LW

Seat Height:

875 mm (34.4 in) for YZ85; 885 mm (34.8 in) for YZ85LW

Wheelbase:

1240 mm (48.8 in) for YZ85; 1270 mm (50.0 in) for YZ85LW

Ground Clearance:

325 mm (12.8 in) for YZ85; 330 mm (13.0 in) for YZ85LW

Wet Weight:

81 kg (178.6 lbs) - approximately, with all necessary operating fluids

Dry Weight:

73 kg (160.9 lbs)

Front Tire Size:

70/100-17 40M (YZ85); 70/100-19 42M (YZ85LW)

Rear Tire Size:

90/100-14 49M (YZ85); 90/100-16 54M (YZ85LW)

Wheel Bolt Pattern:

Not applicable in the traditional car sense; uses spokes and hubs.

🛡️ Safety Features

Crash Test Ratings:

N/A (Motorcycle, not subject to automotive crash testing standards)

Braking System:

Hydraulic disc brakes front and rear for strong stopping power.

Suspension Performance:

High-quality Kayaba suspension provides excellent control and stability, contributing to rider safety.

Ergonomics:

Designed for rider control and comfort during competitive riding.

💡 Technology Features

Infotainment System:

N/A (Pure competition motocross bike, no infotainment features).

Electronic Aids:

N/A (No electronic rider aids like ABS, traction control, etc., on this model).

Connectivity Features:

N/A

🔧 Maintenance

Oil Change Transmission:

Every 15-20 hours of riding, or as recommended by the manual for optimal gearbox lubrication.

Air Filter Cleaning:

Recommended after every few rides or immediately if dirty, especially in dusty conditions.

Spark Plug Inspection:

Check and clean/replace every 20-30 hours of riding, or if fouled.

Top End Rebuild Recommendation:

Typically recommended every 30-50 hours of hard racing use, depending on riding style and maintenance.

Engine Oil:

2-stroke premix oil: Yamaha Yamalube 2R or equivalent meeting JASO FD / ISO-L-EGD standards.

Transmission Oil:

Yamalube 10W-40 API SG SAE 10W-40 or equivalent.

Coolant:

Not applicable (air-cooled engine).

Brake Fluid:

DOT 3 or DOT 4 brake fluid.

Common Wear Items:

Clutch plates, piston rings, spark plugs, wheel bearings, chain and sprockets, suspension seals.

Carburetor Tuning:

Can be sensitive to altitude and temperature changes; proper jetting is crucial for optimal performance and engine longevity.

Suspension Maintenance:

Regular fork seal and oil changes are important to maintain suspension performance and prevent leaks.

📚 Vehicle History

Yamaha Motorsports:

Yamaha has a long and storied history in motorcycle racing, particularly in motocross, dating back to the 1960s. Known for innovation and performance.

Yz Lineage:

The YZ85 is part of Yamaha's highly successful YZ motocross line, which has seen continuous development and refinement over the years to maintain a competitive edge.

Manufacturing Location:

Typically manufactured in Japan.

Yz85 Introduction:

The YZ85 model itself has been a staple in the 85cc class for many years, with the 2005 model representing an evolution of the platform.

🏆 Awards & Recognition

Motocross Reviews:

The YZ85 line consistently receives positive reviews from motocross publications and riders for its performance and handling in its class. Specific awards for the 2005 model may vary, but the platform is generally well-regarded.

Durability Reputation:

Yamaha YZ models are generally known for their robust construction and reliability when properly maintained, making them a good choice for competitive use.