Vehicle Category:
Competition Motorcycle (125cc class)
Target Audience:
Yamaha TZ 125 racers, mechanics, and dedicated enthusiasts.
Competitors:
Other 125cc Grand Prix racing motorcycles of the era, such as Honda RS125, Aprilia RS 125, and Cagiva Mito 125 (though the TZ is purely competition-focused).
Manual Benefit 1:
Enables owners and technicians to perform complex repairs and maintenance efficiently.
Manual Benefit 2:
Provides in-depth understanding of the TZ 125's racing-specific technology.
Manual Benefit 3:
Facilitates accurate troubleshooting and problem diagnosis.
Engine Systems:
Engine overhaul, cooling system, carburetor, internal engine components (pistons, cylinders, crankshaft, connecting rods), lubrication, ignition system, exhaust system.
Chassis Systems:
Frame, suspension (front fork, rear shock absorber), steering, wheels, brakes (front and rear), chain drive, swingarm.
Electrical Systems:
Wiring diagrams, lighting, ignition system components, battery, charging system, controls, instrumentation.
Routine Maintenance:
Periodic inspection and adjustment, chain adjustment, brake adjustments, fluid checks and changes, spark plug maintenance.
Major Repairs:
Engine disassembly and reassembly, carburetor tuning and rebuilding, suspension overhaul, brake caliper service, electrical component troubleshooting and replacement.
Troubleshooting:
Diagnostic procedures for common problems, fault finding charts, symptom-based troubleshooting guides.
Diagnostic Level:
Advanced diagnostics and repair procedures for professional technicians and experienced enthusiasts.
Rebuild Instructions:
Detailed step-by-step instructions for complete engine rebuilds and major component overhauls.
Specifications Detail:
Comprehensive technical specifications, torque values, clearances, fluid capacities, and wear limits.
Engine Type:
Two-stroke, liquid-cooled, single-cylinder
Bore X Stroke:
Typically around 54.0 mm x 54.5 mm (specific figures may vary slightly by year/variant)
Compression Ratio:
High performance ratio, typically in the range of 12.0:1 to 14.0:1 or higher, depending on tuning.
Power Output:
Estimated 35-40+ HP (race-tuned, figures vary significantly with tuning and class regulations).
Torque Output:
Not typically quoted in standard manuals, but designed for high RPM power delivery.
Redline:
High, often exceeding 11,000 RPM, specific figure will be in manual.
Carburetor Type:
High-performance racing carburetor, e.g., Mikuni VM series or similar, with specific jetting and settings detailed in the manual.
Fuel Type:
High-octane racing fuel, often with specific octane rating requirements.
Fuel Delivery:
Gravity feed from fuel tank via carburetor.
Length:
Approx. 1,970 mm (specific figure in manual).
Width:
Approx. 660 mm (specific figure in manual).
Height:
Approx. 1,110 mm (specific figure in manual).
Wheelbase:
Approx. 1,350 mm (specific figure in manual).
Dry Weight:
Approx. 99 kg (specific figure in manual).
Fuel Tank Capacity:
Approx. 10 liters (specific figure in manual).
Safety Classification:
Competition Motorcycle - Not intended or equipped for road use. Safety features are race-specific.
Braking System Front:
Hydraulic disc brake, dual piston caliper (specific caliper/rotor details in manual).
Braking System Rear:
Hydraulic disc brake, single piston caliper (specific caliper/rotor details in manual).
Frame Type:
Aluminum twin-spar frame for rigidity and light weight.
Infotainment System:
N/A - Competition motorcycle focused purely on performance. No infotainment features.
Rider Aids:
N/A - No electronic rider aids. Purely mechanical and rider skill dependent.
Connectivity Features:
N/A - No connectivity features. Designed for track use only.
Ignition System:
CDI (Capacitor Discharge Ignition) with specific ignition timing curves detailed in the manual for optimal power delivery.
Exhaust System:
Expansion chamber exhaust system tuned for the 125cc 2-stroke engine's power band. Manual provides insights into its function.
Oil Change Frequency:
Dependent on racing usage; typically after a set number of race hours or competitive events. Specific recommendations in the manual.
Spark Plug Replacement:
Regular checks and replacement based on race conditions and performance. Manual will specify compatible plug types and heat ranges.
Engine Rebuild Interval:
Variable based on engine stress and usage; manual will guide on signs of wear and recommended rebuild points.
Coolant Type:
Ethylene glycol based, water-cooled coolant. Specific mix ratio and type provided in manual.
Brake Fluid Type:
DOT 4 or DOT 5.1 compatible hydraulic brake fluid. Manual specifies exact type and replacement intervals.
2-Stroke Oil Type:
High-quality, racing-grade 2-stroke oil for premix or oil injection system. Manual specifies recommended brands and viscosity.
Common Wear Items:
Piston rings, clutch plates, brake pads, chain and sprockets, wheel bearings, fork seals due to high-stress racing environment.
Carburetor Tuning:
Carburetor jetting and settings are critical for optimal performance and can require frequent adjustments based on track conditions, altitude, and fuel.
Engine Heat Management:
Proper cooling system maintenance is crucial for preventing overheating in high-performance 2-stroke engines.
Yamaha Motorsport:
Yamaha has a long and successful history in Grand Prix motorcycle racing, known for its innovative two-stroke engines and competitive chassis designs.
Tz Series Legacy:
The TZ series represented Yamaha's commitment to providing competitive 2-stroke machinery for privateer racers across various displacement classes, including the highly popular 125cc category.
Production Era:
The TZ 125 was produced and updated through multiple generations from the late 1970s through the early 2000s, with the G1 designation referring to the 1995 model.
Racing Success:
The TZ 125 platform has been a highly successful platform in amateur and professional 125cc racing series worldwide, contributing to many championships for privateers.
Performance Rating:
Highly rated for its agility, precise handling, and competitive 2-stroke power delivery in its class.
Homologation:
While not road-legal, the TZ 125 was built to specific racing homologation standards for various series of its time.
