Target Audience:
Enthusiasts, mechanics, and owners of the 1985 Yamaha YZ80 for maintenance and repair.
Manual Value Proposition:
Provides essential technical data, procedures, and troubleshooting for the specific 1985 YZ80 model, crucial for maintaining its performance and longevity.
Manual Benefit 1:
Enables DIY maintenance and repairs, saving costs.
Manual Benefit 2:
Ensures adherence to factory specifications for optimal performance and reliability.
Manual Benefit 3:
Facilitates accurate diagnosis of common issues specific to the YZ80.
Engine Systems:
Top-end, bottom-end, cooling, lubrication, fuel system, ignition system, exhaust system
Drivetrain Systems:
Clutch, gearbox, final drive (chain and sprockets)
Chassis Systems:
Frame, suspension (front forks, rear shock absorber), steering, wheels, tires
Braking Systems:
Front drum brake, rear drum brake, control cables
Electrical Systems:
Ignition system, lighting (if applicable), wiring diagrams, component testing
Bodywork And Trim:
Body panels, seat, fuel tank, fenders
Maintenance Procedures:
Routine checks, oil changes, filter replacements, chain adjustment, spark plug service, pre-ride inspections
Repair Procedures:
Engine top-end rebuild (piston, rings, cylinder), carburetor overhaul, clutch service, gearbox disassembly and reassembly, fork seal replacement, shock absorber service, brake adjustment and component replacement
Troubleshooting Guides:
Diagnostic charts for common starting issues, running problems, and performance complaints
Technical Specifications:
Torque specifications, clearances, measurements, wiring diagrams, component identification
Depth Of Coverage:
Comprehensive: From basic maintenance to complete engine and chassis overhauls. Includes detailed disassembly and reassembly instructions.
Engine Type:
Two-stroke, single-cylinder
Displacement:
79 cc (4.8 cu in)
Bore X Stroke:
48.0 x 44.0 mm
Cooling System:
Liquid-cooled
Carburetor:
Mikuni VM24SS (typical specification)
Ignition System:
CDI (Capacitor Discharge Ignition)
Compression Ratio:
7.6:1 (typical, may vary slightly)
Power Output Hp:
Approximately 14-16 HP (estimated for the era)
Fuel Type:
Unleaded gasoline with 2-stroke oil mix
Fuel Oil Ratio:
50:1 (standard, refer to manual for exact specification)
Transmission Type:
6-speed manual
Length:
Approximately 1,865 mm (73.4 in)
Width:
Approximately 790 mm (31.1 in)
Height:
Approximately 1,135 mm (44.7 in)
Wheelbase:
Approximately 1,275 mm (50.2 in)
Dry Weight:
Approximately 75 kg (165 lbs)
Fuel Tank Capacity:
Approximately 5.2 liters (1.4 US gal)
Oil Change Interval:
Refer to manual (typically after break-in and every 10-15 hours of riding)
Spark Plug Check Interval:
Refer to manual (often checked every 5-10 hours of riding)
Air Filter Cleaning Interval:
Refer to manual (frequently, depending on riding conditions)
Chain Lubrication Interval:
Refer to manual (frequently, before and after rides)
Transmission Oil Type:
Yamaha Gear Oil or equivalent SAE 10W-30 API SE/CC (refer to manual for exact specification)
Coolant Type:
Distilled water and anti-freeze (ethylene glycol based) – specific mixture ratio in manual.
Fork Oil Type:
Yamalube Fork Oil or SAE 10W (refer to manual for specific grade and quantity)
Common Wear Item 1:
Piston and rings due to two-stroke nature and high-stress operation.
Common Wear Item 2:
Clutch plates can wear with aggressive use.
Common Wear Item 3:
Carburetor jets can become clogged with age and improper fuel storage.
Common Wear Item 4:
Front fork seals are prone to leaks from off-road impact.
Pre Ride Check Importance:
Crucial for off-road safety: Check tire pressure, chain tension, brakes, and fluid levels before every ride.
Yamaha Motorsports Legacy:
Yamaha has a long and storied history in motocross and off-road racing, with the YZ line being a cornerstone of their competitive lineup.
Yz80 Development:
The YZ80 was a popular entry-level and junior motocross bike throughout the 1970s and 80s, undergoing continuous development for improved performance and handling.
Manufacturing Country:
Japan (typical for Yamaha models of this era)
Production Period:
The YZ80 model line was produced for many years, with significant updates occurring throughout its lifespan.
