Market Position:
The 2006 Yamaha YZ125 was a highly competitive entry in the 125cc two-stroke motocross segment, known for its potent engine performance and agile handling. This model was a favorite among amateur and professional racers seeking a lightweight and powerful machine for MX tracks.
Competitive Analysis:
Competitors in this era included models like the Honda CR125R, Suzuki RM125, and Kawasaki KX125. The YZ125 of this generation was often praised for its strong mid-range power delivery and its advanced KYB suspension components.
Key Features:
Liquid-cooled 125cc two-stroke engine, YPVS (Yamaha Power Valve System), aluminum frame, adjustable KYB suspension (SSS - Speed Sensitive System on some models of this generation, but likely conventional on 2006), powerful braking system, strong rider ergonomics.
Manual Title:
2006 Yamaha YZ125 Service Manual Repair
Manual Type:
Factory Service Manual / Repair Manual
Manual Purpose:
Designed for mechanics and owners to perform all necessary service, repair, and maintenance tasks to keep the motorcycle in optimal working condition.
Format:
Digital Download (likely PDF)
Systems Covered:
Engine (complete teardown and rebuild), Fuel System, Ignition System, Lubrication System, Cooling System (if applicable, though typically air-cooled), Transmission, Clutch, Chassis, Suspension (Front and Rear), Brakes (Front and Rear), Electrical System, Wiring Diagrams, Frame, Bodywork, Controls, Wheels, Tires.
Electrical System Details:
Comprehensive coverage of the DC-CDI ignition system, lighting (if equipped), and all associated wiring, including detailed wiring diagrams for troubleshooting.
Procedures Included:
Complete disassembly and reassembly, routine maintenance, troubleshooting common issues, component diagnostics, detailed repair procedures, torque specifications for all fasteners, adjustments, part replacement, performance tuning (basic), carburetor tuning and overhaul, suspension setup and servicing, brake bleeding and pad replacement, electrical component testing and repair, clutch adjustment and service.
Troubleshooting Guide:
Yes, the manual contains dedicated sections for troubleshooting various mechanical and electrical issues, providing diagnostic steps and potential solutions.
Technical Depth:
Comprehensive. Covers everything from basic maintenance to complete engine and chassis overhauls, suitable for both home mechanics and professional technicians.
Diagnostic Tools:
Details required specialized tools, measurement gauges (e.g., compression tester, feeler gauges), torque wrenches, and specific Yamaha tools for certain procedures.
File Format:
PDF (assumed for digital download)
Print Quality:
High-resolution scans of original factory documentation, ensuring clarity of text, diagrams, and photographs.
Binding Type:
N/A (Digital Download)
Paper Type:
N/A (Digital Download)
Searchable Text:
High probability of being text-searchable if it's a well-created PDF, greatly enhancing the ability to quickly find specific information.
Engine Displacement:
125cc
Engine Compression Ratio:
8.6:1 (or similar, specific value in manual)
Engine Cooling System:
Liquid-cooled
Engine Valvetrain:
Reed Valve Induction, YPVS (Yamaha Power Valve System)
Horsepower:
Approx. 37-40 HP (typical for class)
Torque:
Not typically quoted for MX bikes, but peak torque occurs in mid-range.
Power Delivery:
Known for a strong, aggressive mid-range powerband, characteristic of high-performance two-stroke motocross engines.
Carburetor Type:
Keihin PWK38S (38mm slide carburetor)
Fuel Type:
Unleaded Gasoline (91-98 octane recommended)
Fuel Mixture:
50:1 (Gasoline to 2-Stroke Oil Ratio, specified by Yamaha)
Length:
Approximately 2,160 mm (85.0 in)
Width:
Approximately 800 mm (31.5 in)
Height:
Approximately 1,260 mm (49.6 in)
Wheelbase:
Approximately 1,450 mm (57.1 in)
Ground Clearance:
Approximately 355 mm (14.0 in)
Seat Height:
Approximately 990 mm (39.0 in)
Dry Weight:
Approximately 91 kg (201 lbs)
Wet Weight:
Not officially quoted, but typically ~100 kg (220 lbs) with fluids.
Fuel Capacity:
7.2 Liters (1.9 US gal)
Safety Ratings:
N/A (Motorcycles not rated by typical automotive crash agencies)
Active Safety Features:
Powerful disc brakes (front and rear), agile handling chassis, effective suspension system.
Passive Safety Features:
Durable frame construction, protective bodywork (fairings, fenders).
Service Intervals:
This manual will detail specific intervals for: Air filter cleaning/replacement, spark plug inspection/replacement, chain cleaning/lubrication/adjustment, brake pad inspection, coolant flush, oil changes (transmission), general inspection and lubrication. Intervals are typically based on operating hours or mileage.
Engine Rebuild Frequency:
The manual provides guidance on engine wear indicators and recommended times for top-end (piston/rings) and full engine rebuilds based on usage and performance degradation.
Engine Oil Type:
Yamalube 2R or other high-quality JASO FD certified 2-stroke premix oil.
Transmission Oil Type:
Yamalube 10W-30 or equivalent API 'SE'/'SF'/'SG' type engine oil.
Coolant Type:
Yamaha Coolant (or equivalent permanent type, ethylene glycol-based antifreeze mixed 50/50 with distilled water).
Brake Fluid Type:
DOT 3 or DOT 4 brake fluid.
Common Issues:
Like many high-performance two-strokes, potential issues include: premature piston/ring wear if not properly maintained, carburetor jetting sensitivity to altitude/temperature, clutch wear from aggressive riding, wear on the power valve system, and occasional electrical gremlins if wiring is damaged.
Suspension Wear:
Wear on fork seals, bushings, and shock absorber components is common with extensive off-road use and is detailed in the maintenance section.
Brand Heritage:
Yamaha has a long and storied history in motocross, dating back to the early days of the sport. The YZ line, particularly the 125cc two-stroke, has been a cornerstone of Yamaha's off-road racing success for decades.
Model Evolution:
The YZ125 has undergone continuous development since its inception. The 2006 model represents an evolution of Yamaha's successful aluminum frame design introduced in 2005, featuring refined engine characteristics and suspension tuning for improved performance.
Production Years:
The YZ125 has been in continuous production from the 1970s to the present day in various iterations. The specific 2006 model was part of the generation featuring the generation-defining aluminum frame.
