🏷️ Basic Information

Make:

Yamaha

Model:

YZ80

Year:

1987

Engine Code:

4ES

Chassis Code:

4ES

👋 Introduction

Market Segment:

Entry-level to intermediate motocross/off-road competition and recreational riding.

Target Audience:

Young motocross riders, off-road enthusiasts, and mechanics responsible for the maintenance and repair of the YZ80.

Competitors:

Honda CR80R, Kawasaki KX80, Suzuki RM80.

Vehicle Key Features:

Lightweight chassis, potent two-stroke engine, adjustable suspension, robust build quality for its class.

Manual Key Features:

Authoritative documentation, detailed illustrations, step-by-step procedures, comprehensive troubleshooting guides.

📋 Manual Details

Model Years Covered:

1987

Specific Models Covered:

Yamaha YZ80 (YZ 80)

Page Count:

Estimated 250-300 pages (typical for this era of service manual)

Manual Type:

Service Repair Workshop Manual

Language:

English

Format:

Digital (likely PDF)

File Format:

PDF

Print Quality:

High-resolution scans, clear diagrams and text.

Binding Type:

N/A (Digital Format)

Paper Type:

N/A (Digital Format)

📖 Manual Coverage

Engine System:

Complete engine disassembly, assembly, tuning, troubleshooting, top-end rebuild, bottom-end rebuild, lubrication system.

Fuel System:

Carburetor disassembly, cleaning, adjustment, jetting, fuel tank, fuel lines, fuel petcock.

Ignition System:

CDI unit, spark plug, ignition coil, stator, troubleshooting.

Cooling System:

Air cooling system, cooling fins, general airflow management.

Transmission System:

Gearbox disassembly, assembly, clutch operation, shift mechanism, lubrication.

Suspension System:

Front fork service, rear shock absorber service, linkage maintenance, spring rates, damping adjustments.

Brake System:

Front and rear brake system maintenance, brake fluid, bleeding procedure, pad replacement, caliper service.

Electrical System:

Lighting system, wiring diagrams, fuse replacement, battery maintenance, troubleshooting common electrical faults.

Chassis And Frame:

Frame inspection, subframe, steering head bearings, general chassis components.

Wheels And Tires:

Wheel bearing service, spoke tension adjustment, tire pressure, tire replacement.

Bodywork:

Plastic body panel removal and installation, seat, fenders.

Maintenance Procedures:

Routine maintenance checks, oil changes, filter replacements, spark plug checks, chain adjustments, pre-ride inspections.

Repair Procedures:

Engine overhaul, transmission repair, suspension rebuild, brake system repairs, carburetor tuning, electrical fault diagnosis.

Troubleshooting:

Detailed diagnostic flowcharts for common problems, identifying causes of poor performance, starting issues, and operational faults.

Torque Specifications:

Precise torque values for all critical fasteners and components.

Special Tools:

Identification and usage of specialized tools required for specific repair and maintenance tasks.

Technical Depth:

Comprehensive coverage from basic rider maintenance to complete engine and transmission rebuilds, suitable for both novice and experienced mechanics.

⚙️ Engine Specifications

Engine Type:

Liquid-cooled, 2-stroke, reed valve induction

Displacement:

78 cc (4.76 cu in)

Bore X Stroke:

47.0 x 45.6 mm (1.85 x 1.80 in)

Compression Ratio:

7.6:1 (typical, may vary slightly)

Carburetor:

Mikuni VM24SS

Ignition:

CDI Magneto

Starting System:

Kickstarter

Lubrication:

Pre-mix (Fuel/Oil mixture)

Horsepower:

Approx. 17.5 HP @ 9500 RPM (estimated for this model year)

Torque:

Approx. 9.0 lb-ft @ 8500 RPM (estimated for this model year)

Fuel Type:

Unleaded gasoline (91 octane or higher recommended)

Fuel Oil Mixture Ratio:

50:1 (Yamaha recommends specific 2-stroke oil for this ratio)

🔧 Transmission

Transmission Type:

6-speed constant mesh

Clutch Type:

Wet, multi-plate

Gear Ratios:

Detailed gear ratios are provided in the manual for each gear.

Transmission Oil:

Yamaha recommended 2-stroke transmission oil (e.g., SAE 80 or 90 API GL-4)

Transmission Oil Capacity:

Approx. 0.6 Liters (0.63 US qt)

📐 Dimensions

Overall Length:

Approx. 1850 mm (72.8 in)

Overall Width:

Approx. 780 mm (30.7 in)

Overall Height:

Approx. 1120 mm (44.1 in)

Wheelbase:

Approx. 1280 mm (50.4 in)

Ground Clearance:

Approx. 330 mm (13.0 in)

Seat Height:

Approx. 855 mm (33.7 in)

Dry Weight:

Approx. 74 kg (163 lbs)

Wet Weight:

Approx. 79 kg (174 lbs) (with fluids)

Fuel Tank Capacity:

6.5 Liters (1.7 US gal)

🛡️ Safety Features

Safety Ratings:

N/A (Off-road competition vehicle, not rated for road use or consumer safety tests like NHTSA/Euro NCAP)

Active Safety Features:

Effective braking system (disc front, drum rear), responsive handling.

Passive Safety Features:

Sturdy frame construction, rider protection elements as part of motocross gear (not vehicle integrated).

💡 Technology Features

Infotainment Features:

N/A (No infotainment system on this model)

Driver Assistance Features:

N/A (No electronic driver assistance features)

Connectivity Features:

N/A (No connectivity features)

🔧 Maintenance

Oil Change Interval:

Transmission oil change every 15-20 hours of riding or annually. Pre-mix oil replenishment at each refueling.

Air Filter Cleaning:

Clean after every few rides or as needed based on riding conditions.

Spark Plug Check:

Check and clean/replace every 10-15 hours of riding or as performance dictates.

Chain Tension Adjustment:

Check and adjust weekly or before each riding session.

Top End Rebuild:

Recommended every 40-60 hours of hard riding, or when compression is noticeably reduced.

Two Stroke Oil Type:

Yamaha genuine 2-stroke oil (or equivalent high-quality JASO FD rated 2-stroke oil).

Brake Fluid:

DOT 3 or DOT 4 brake fluid.

Coolant:

N/A (Air-cooled engine)

Common Issues:

Carburetor jetting sensitivity to altitude/temperature, wear on clutch plates due to usage, fork seal leaks, chain and sprocket wear.

Preventative Maintenance:

Regular cleaning of the air filter, proper pre-mix ratio, and timely transmission oil changes are crucial for engine longevity.

📚 Vehicle History

Brand Heritage:

Yamaha has a long and successful history in motorcycle racing, particularly in motocross and off-road disciplines, known for performance and innovation.

Yz Series Evolution:

The YZ80 has been a cornerstone of Yamaha's junior motocross lineup for decades, undergoing continuous refinement to improve performance, handling, and reliability.

Production Era:

The YZ80 was produced for many years, with the 1987 model representing a specific iteration within its long production run.

🏆 Awards & Recognition

Historical Recognitions:

While specific awards for the 1987 YZ80 are not widely documented as standalone accolades, the YZ series has consistently been a dominant force in amateur and professional motocross racing, winning numerous championships and earning a reputation for performance and durability.