Category:
Motocross / Off-Road Performance Motorcycle
Target Audience:
Enthusiasts, mechanics, and owners of the 1989 Yamaha YZ80
Competitors:
Honda CR80R, Kawasaki KX80, Suzuki RM80
Vehicle Focus:
Lightweight, agile, powerful for its class, competitive in 80cc motocross racing
Manual Value:
Provides essential knowledge for maintenance, repair, and optimization of the YZ80
Engine:
Full overhaul, tuning, carburetor, ignition, cooling
Transmission:
Clutch, gearbox, shifting mechanism
Chassis:
Frame, suspension (front forks, rear shock), steering
Brakes:
Front and rear brake system inspection, service, and adjustment
Electrical:
Ignition system, lighting, wiring diagrams
Fuel System:
Fuel tank, fuel lines, carburetor disassembly and adjustment
Exhaust:
Exhaust pipe and silencer service
Cooling System:
Air-cooled engine maintenance
Preventative Maintenance:
Scheduled maintenance, lubrication, inspections
Troubleshooting:
Diagnostic guides for common problems and symptoms
Repair Procedures:
Step-by-step instructions for component disassembly, repair, and reassembly
Tune Up:
Carburetor tuning, ignition timing adjustment
Rebuilds:
Engine and transmission overhaul instructions
Depth:
Comprehensive: from basic maintenance to full engine rebuilds and advanced diagnostics
Quality:
High-resolution scans or native digital files, ensuring clarity of text and diagrams
Recommendation:
Suitable for professional printing for a physical copy
Suggestion:
Coil or comb binding for lay-flat usability in a workshop environment
Suggestion:
Heavyweight, glossy paper to withstand workshop conditions and enhance diagram legibility
Type:
Two-stroke, single-cylinder, reed valve induction
Displacement:
79.9 cc (4.88 cu in)
Bore X Stroke:
47.0 x 47.0 mm (1.85 x 1.85 in)
Compression Ratio:
7.8:1 (typical, may vary)
Cooling System:
Forced air-cooled
Carburetor:
Mikuni VM24SS (typical)
Horsepower Estimate:
Approx. 17-18 HP @ 10,500 RPM (manufacturer claims vary)
Torque Estimate:
Approx. 7.5-8.0 lb-ft @ 9,000 RPM (estimate)
Fuel Type:
Unleaded gasoline with 2-stroke oil mix (e.g., 20:1 or 32:1 depending on oil type and manufacturer recommendation)
Fuel Capacity:
5.0 Liters (1.3 US gal)
Type:
CDI (Capacitor Discharge Ignition)
Spark Plug:
NGK BR9ES (typical)
Spark Plug Gap:
0.7-0.8 mm (0.028-0.031 in)
Type:
6-speed constant mesh manual
Gear Ratios:
Refer to manual for specific gear ratios
Transmission Oil Type:
Yamaha Gear Oil or SAE 80W API GL-4 (refer to manual for precise spec)
Transmission Oil Capacity:
Approx. 0.75 Liters (0.79 US qt)
Length:
1835 mm (72.2 in)
Height:
1100 mm (43.3 in)
Wheelbase:
1275 mm (50.2 in)
Ground Clearance:
310 mm (12.2 in)
Seat Height:
840 mm (33.1 in)
Dry Weight:
76 kg (167.6 lbs)
Wet Weight:
Approx. 82-85 kg (180-187 lbs) with fluids
Travel:
Approx. 275 mm (10.8 in)
Oil Type Capacity:
Refer to manual for specific fork oil type and quantity (e.g., Yamalube Fork Oil or equivalent)
Type:
Monocross (single shock absorber with linkage)
Travel:
Approx. 280 mm (11.0 in)
Front Wheel:
1.60 x 21 inch
Rear Wheel:
1.85 x 18 inch
Front Tire:
80/100-21 (typical)
Rear Tire:
100/100-18 (typical)
Tire Pressure Front:
Refer to manual for optimal pressure (typically 15-20 psi for off-road)
Tire Pressure Rear:
Refer to manual for optimal pressure (typically 15-20 psi for off-road)
Oil Change Transmission:
Every 15-20 hours of riding or annually (refer to manual for precise recommendation)
Air Filter Cleaning:
After every few rides or as needed depending on conditions (critical for two-strokes)
Spark Plug Inspection:
Every 10-15 hours of riding
Chain Lubrication Adjustment:
After every ride or as needed
Two Stroke Oil Mix:
Yamalube 2T or equivalent high-quality 2-stroke oil at 20:1 or 32:1 ratio (verify with manual)
Brake Fluid:
DOT 3 or DOT 4 hydraulic brake fluid (check manual for specific DOT rating)
Carburetor Fouling:
Common in two-strokes; requires regular cleaning and jetting adjustments, especially with varying fuel quality or riding conditions.
Clutch Wear:
Clutch plates can wear out with aggressive riding; adjustment and eventual replacement are standard maintenance.
Suspension Seals:
Fork seals and rear shock seals can leak over time; regular inspection and replacement are recommended.
Engine Top End:
Piston and ring wear is normal for a high-performance two-stroke; requires periodic replacement based on hours of use.
Legacy:
Yamaha has a long and successful history in motocross and off-road racing, with the YZ line being a cornerstone of their performance offerings.
Yz80 Lineage:
The YZ80 was a highly competitive entry-level motocross bike, evolving significantly through the 1980s with chassis updates, engine improvements, and suspension advancements.
1989 Updates:
The 1989 model typically featured refined suspension, improved power delivery, and updated styling compared to earlier versions.
Manufacturing Origin:
Japan
