Model Codes:
TZ125G, TZ125G1, TZM
Vehicle Type:
Competition Motorcycle (2-stroke)
Production Years Covered:
1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
Manual Product Name:
Yamaha TZ125 Factory Repair Manual 1990-2005 Download PDF
Target Audience:
Do-it-yourself enthusiasts and experienced mechanics.
Value Proposition:
Inexpensive alternative to dealer servicing, comprehensive repair and maintenance resource.
Alternatives:
Dealer service manuals (often more expensive and less accessible), aftermarket repair guides (may lack factory detail).
Completeness:
COMPLETE factory service workshop repair manual.
Accessibility:
Instant download, no shipping or waiting required.
Instructional Style:
Numbered instructions, bold figure numbers for quick illustration matching.
Engine:
Complete disassembly, assembly, tuning, and troubleshooting of the 125cc 2-stroke engine.
Transmission:
Gearbox inspection, repair, and adjustment procedures.
Clutch:
Wet multi-plate clutch service, adjustment, and component replacement.
Cooling System:
Liquid cooling system maintenance, radiator service, and coolant specifications.
Fuel System:
Carburetor (likely Mikuni VM series) tuning, overhaul, and jetting specifications. Fuel tank and line service.
Ignition System:
CDI ignition system, spark plug selection, timing checks, and troubleshooting.
Electrical System:
Comprehensive wiring diagrams, lighting system, charging system (stator/generator), and troubleshooting for electrical faults.
Exhaust System:
Expansion chamber maintenance, exhaust port cleaning, and tuning considerations.
Suspension Front:
Front fork (likely upside-down) disassembly, oil change, seal replacement, and damping adjustments.
Suspension Rear:
Monoshock rear suspension service, linkage maintenance, and shock absorber adjustment.
Brakes Front:
Hydraulic disc brake system service, caliper overhaul, pad replacement, and bleeding procedures.
Brakes Rear:
Hydraulic disc brake system service, caliper overhaul, pad replacement, and bleeding procedures.
Wheels And Tires:
Wheel bearing service, tire mounting and balancing, rim specifications.
Frame And Bodywork:
Frame inspection, fairing removal and installation, seat, and tank components.
Controls:
Throttle, clutch, and brake lever adjustment and replacement.
Routine Maintenance:
Oil changes, filter replacements, chain adjustment, spark plug service, general inspection.
Engine Rebuild:
Top-end rebuild (piston, rings, cylinder), bottom-end rebuild (crankshaft, bearings), complete engine overhaul.
Troubleshooting:
Step-by-step diagnostic procedures for common and uncommon problems across all systems.
Electrical Diagnostics:
Detailed guidance for diagnosing and repairing electrical issues using wiring diagrams.
Suspension Tuning:
Instructions for adjusting damping, spring preload, and fork oil levels for optimal performance.
Carburetor Tuning:
Jetting charts, idle speed adjustment, mixture control, and float level settings.
Brake System Overhaul:
Caliper seal replacement, piston servicing, master cylinder repair, and fluid bleeding.
Component Replacement:
Detailed instructions for replacing all major and minor components.
Depth:
Comprehensive (from basic maintenance to complete engine and chassis rebuilds).
Detail Level:
Detailed substeps, critical notes, cautions, and warnings.
Illustrations:
Hundreds of photos and detailed illustrations, drawings, and enlarged insets.
Troubleshooting Aid:
Dedicated troubleshooting sections and integrated electrical system diagnostics.
Engine Type:
Liquid-cooled, 2-stroke, reed valve induction
Displacement:
124 cc (approximate, specific variations may exist across years)
Bore X Stroke:
Typically around 56.0 mm x 50.0 mm (exact specifications in manual)
Compression Ratio:
Variable by year and tuning, generally high for competition use (e.g., 8.5:1 to 10.5:1 or higher for racing tunes).
Horsepower:
Speculative, but typically in the 30-40 HP range for a well-tuned TZ125 of this era, higher for race-prepped models.
Torque:
Speculative, but proportional to horsepower.
Carburetor Type:
Single Mikuni VM series (e.g., VM28 or VM30, specific to year and model variant).
Fuel Type:
Unleaded gasoline mixed with 2-stroke oil (pre-mix or Autolube system, depending on variant). Octane rating as per Yamaha recommendation, likely premium.
Lubrication Type:
Premix or Autolube (oil injection system).
Engine Top End:
Frequent rebuilds for competition use (piston/ring replacement every few race weekends), more lenient for recreational use.
Oil Change:
Transmission oil: Recommended every few thousand kilometers or as per manual, depending on usage intensity.
Chain Maintenance:
Lubrication and adjustment recommended every 500-1000 km, or more frequently in wet/dirty conditions.
Engine Oil:
High-quality 2-stroke racing oil, specific type and ratio (e.g., 1:20, 1:25, 1:30) depending on Yamaha's recommendation and application. (Manual will specify).
Transmission Oil:
Yamalube Gear Oil SAE 10W-30 or equivalent API GL-4 specification (Manual will specify exact viscosity and API rating).
Coolant:
Permanent type antifreeze coolant (50/50 mix with distilled water) (Manual will specify).
Brake Fluid:
DOT 4 hydraulic brake fluid (Manual will specify).
Carburetor Tuning Sensitivity:
2-stroke engines are sensitive to jetting changes due to altitude, temperature, and humidity. Requires regular tuning.
Engine Wear:
High-performance 2-stroke engines require regular top-end maintenance to maintain peak performance and prevent catastrophic failure.
Clutch Wear:
Clutch plates can wear out due to hard use, requiring periodic replacement.
