Market Segment:
Competitive 125cc two-stroke racing motorcycle
Competitors:
Honda RS125, Aprilia RS 125, Suzuki RG125
Performance Focus:
Designed for track use and racing, emphasizing high power output from a small displacement engine.
Manual Value Proposition:
Indispensable resource for owners and mechanics to maintain and repair the TZ 125 to peak performance.
Engine Mechanical:
Complete engine disassembly, assembly, tuning, and rebuilding
Engine Performance:
Carburetion tuning, power valve operation, exhaust system analysis
Fuel System:
Carburetor overhaul, fuel line inspection, fuel tank maintenance
Ignition System:
CDI unit, spark plug specifications, ignition timing
Transmission And Drivetrain:
Clutch operation, gear selection, chain and sprockets maintenance
Cooling System:
Radiator, coolant flow, fan operation (if applicable)
Suspension System:
Front fork overhaul, rear shock absorber adjustment and replacement, linkage maintenance
Braking System:
Front and rear brake caliper service, master cylinder overhaul, brake line replacement, pad and disc specifications
Electrical System:
Wiring diagrams, lighting systems, charging system, starter system (if applicable)
Chassis And Frame:
Frame inspection, steering head bearing service, swingarm maintenance
Bodywork And Fairings:
Fairing removal and installation, seat maintenance, tank replacement
Basic Maintenance:
Oil changes, filter replacements, chain lubrication, tire pressure checks
Intermediate Repairs:
Carburetor cleaning and adjustment, brake pad replacement, fork seal replacement
Advanced Rebuilds:
Full engine rebuild, transmission overhaul, suspension component refurbishment
Troubleshooting Guides:
Diagnostic procedures for common performance issues and electrical faults
Torque Specifications:
Detailed torque settings for all critical fasteners
Fluid Capacities:
Precise fluid volumes for engine oil, coolant, transmission fluid, brake fluid
Electrical Diagrams:
Comprehensive and detailed wiring schematics
Special Tool Requirements:
Identification of necessary specialized tools for specific procedures
Depth Of Coverage:
Comprehensive, suitable for full motorcycle rebuilds
Engine Type:
Liquid-cooled, 2-stroke, single-cylinder
Bore X Stroke:
54.0 mm x 54.5 mm
Compression Ratio:
8.8:1 (Typical for racing applications, may vary slightly)
Power Valve System:
Yamaha Power Valve (YPVS) for optimized power delivery across rev range
Horsepower Peak:
Approximately 36-40 HP (at crankshaft, depending on tuning and race specifications)
Torque Peak:
Not commonly published for racing bikes in street-legal terms; performance oriented.
Carburetor Type:
Mikuni TM34SS (flat slide, 34mm)
Fuel Type:
Unleaded gasoline (minimum 95 RON) with 2-stroke oil pre-mix (e.g., 32:1 ratio recommended by Yamaha, refer to manual for specific blend).
Ignition Type:
Digital CDI (Capacitor Discharge Ignition)
Engine Oil Change:
Refer to manual; typically after every few race weekends or specific hours of use.
Spark Plug Replacement:
Frequent replacement is recommended for optimal performance in racing.
Top End Rebuild:
Recommended after a set number of race hours/miles to maintain compression and power.
Engine Oil:
Specific 2-stroke racing oil blend (e.g., Yamalube Racing 2T or equivalent recommended by manual).
Coolant:
Mixture of distilled water and appropriate motorcycle coolant (e.g., 50/50).
Brake Fluid:
DOT 4 (or as specified in manual for optimal performance and heat resistance).
Carburetor Fouling:
Common with 2-strokes if not maintained or if incorrect jetting is used; the manual provides detailed cleaning and adjustment procedures.
Power Valve Sticking:
Can occur due to carbon buildup; the manual details cleaning and lubrication procedures.
Clutch Wear:
High-performance 2-strokes can put significant stress on clutches; the manual covers clutch inspection and replacement.
Yamaha Racing Legacy:
Yamaha has a long and successful history in motorcycle racing across various disciplines, including Grand Prix.
Tz Series:
The TZ series is a lineage of highly competitive 2-stroke racing motorcycles developed by Yamaha for privateer racers.
Production Era:
The TZ 125 was produced and updated through the 1980s and 1990s, with the G1 representing a specific iteration.
