Segment:
Motocross / Off-Road Competition Youth Motorcycle
Target Audience:
Enthusiasts, mechanics, and owners of the 1986 Yamaha YZ80 looking for detailed repair and maintenance information
Competitors Era:
Honda CR80, Suzuki RM80, Kawasaki KX80
Yz80 Legacy:
The YZ80 was a staple in junior motocross, known for its performance and Yamaha's robust engineering of the era.
Primary Coverage:
1986 Yamaha YZ80
Secondary Coverage Links:
1981 Yamaha YZ80, 1985 Yamaha YZ80
Estimated Page Count:
Varies (typically 200-400 pages for this era/type of manual)
Type:
Service Repair Workshop Manual
Format:
Digital (likely PDF)
Engine:
Complete engine disassembly, assembly, tuning, and troubleshooting
Transmission:
Gearbox inspection, repair, and maintenance
Suspension:
Front fork (conventional telescopic) and rear suspension (Monocross system) maintenance, repair, and adjustments
Brakes:
Front and rear brake system (drum brakes for this era) inspection, maintenance, and component replacement
Electrical System:
Ignition system, lighting, wiring diagrams, component testing, and troubleshooting
Fuel System:
Carburetor (likely Mikuni VM series) tuning, cleaning, and overhaul; fuel tank and petcock maintenance
Cooling System:
Air-cooled engine specifications and maintenance
Chassis Frame:
Frame inspection, fork alignment, and general chassis maintenance
Exhaust System:
Exhaust pipe and silencer maintenance
Routine Maintenance:
Oil changes, filter cleaning/replacement, chain adjustment, lubrication points
Troubleshooting:
Diagnostic charts and common problem resolution for engine, electrical, and chassis issues
Disassembly Assembly:
Step-by-step instructions for major component overhauls (engine, transmission, suspension)
Adjustments:
Carburetor jetting, ignition timing, suspension sag, chain tension, brake lever play
Rebuilds:
Detailed procedures for engine rebuilds, including piston, ring, and cylinder inspection/replacement
Depth:
Comprehensive, covering all aspects from basic maintenance to complete engine and chassis rebuilds
Type:
2-stroke, single-cylinder, reed valve inducted, air-cooled
Displacement:
79 cc (approx.)
Bore X Stroke:
Approx. 48.0 mm x 44.0 mm (typical for this model, confirm in manual)
Compression Ratio:
Typically around 7.0:1 to 7.5:1 (confirm in manual)
Horsepower:
Approx. 15-18 HP (typical for this class, specific to tuning)
Torque:
Subject to tuning and RPM, detailed specs would be in the manual
Carburetor:
Mikuni VM Series (e.g., VM26 or similar)
Fuel Type:
Unleaded gasoline (91-octane or higher recommended) mixed with 2-stroke oil
Premix Ratio:
Typically 20:1 or 25:1, consult manual for exact specification and oil type
Type:
CDI (Capacitor Discharge Ignition)
System:
Premix lubrication
Oil Change:
Frequent checks and changes recommended based on usage; consult manual for specific mileage or operating hour recommendations.
Air Filter Cleaning:
Crucial for 2-stroke engines; clean after every few rides or as per manual recommendations.
Chain Maintenance:
Regular cleaning, lubrication, and tension adjustment are vital for performance and longevity.
Engine Oil Type:
High-quality 2-stroke motorcycle oil, specific viscosity and API rating in manual (e.g., JASO FD/FC).
Transmission Oil:
SAE 80W or SAE 90W gear oil (confirm capacity and exact spec in manual).
Fork Oil:
Specific viscosity and quantity required for front forks; manual will detail this.
Common Wear Items:
Piston rings, clutch plates, fork seals, swingarm bearings, and wheel bearings are common wear items on performance off-road bikes of this era.
Carburetor Fouling:
Can occur with incorrect fuel/oil mixture or dirty air filters.
Exhaust Port Cleaning:
Carbon buildup in the exhaust port and power valve (if equipped) can affect performance.
Yamaha Legacy:
Yamaha has a long and storied history in off-road and motocross racing, consistently producing competitive machinery.
Yz Lineage:
The YZ80 was a key model in Yamaha's junior motocross development, evolving through many iterations focusing on power, suspension, and handling.
Production Years:
The YZ80 was produced across several decades, with significant updates occurring periodically. The 1986 model represents a specific generation of this popular youth bike.
