Category:
Motocross / Off-Road Competition
Competitors 1995:
Honda CR125R, Kawasaki KX125, Suzuki RM125
Engine Type:
High-performance 2-stroke, liquid-cooled
Suspension:
Advanced Kayaba (KYB) suspension, typically inverted front forks and Monocross rear suspension.
Value Proposition:
Enables owners and mechanics to perform all necessary maintenance, repairs, and diagnostics to keep the YZ125 in peak condition.
Engine:
Top-end rebuild, bottom-end overhaul, carburetor tuning, cooling system, lubrication.
Transmission:
Clutch assembly, gearbox disassembly and assembly, shifting mechanism.
Chassis:
Frame inspection and repair, suspension (front forks and rear shock), steering system, swingarm.
Brakes:
Hydraulic brake system inspection, bleeding procedures, pad replacement, caliper maintenance.
Electrical:
Ignition system, lighting circuits, wiring diagrams, battery maintenance, component testing.
Fuel System:
Fuel tank, fuel lines, fuel petcock, carburetor disassembly and cleaning.
Exhaust System:
Exhaust pipe and silencer maintenance, gasket replacement.
Scheduled Maintenance:
Pre-ride checks, oil changes, air filter cleaning, chain adjustment, spark plug replacement.
Troubleshooting:
Diagnostic charts for common running issues, electrical faults, and mechanical problems.
Disassembly Assembly:
Step-by-step instructions for major component removal and installation.
Rebuilding:
Detailed procedures for engine and transmission rebuilds.
Adjustments:
Carburetor jetting, clutch cable, throttle cable, suspension settings.
Engine Top End Rebuild:
Complete guide to cylinder head removal, piston and ring replacement, cylinder inspection, and reassembly.
Engine Bottom End Rebuild:
Detailed instructions for crankshaft inspection and replacement, connecting rod, crankcase separation and assembly, and bearing replacement.
Suspension Servicing:
Front fork seal replacement, oil change, and general fork service; rear shock absorber maintenance and oil/gas charging procedures (if applicable).
Wiring Diagrams:
Complete, detailed electrical wiring schematics for easy fault finding and component identification.
Carburetor Rebuild:
Step-by-step disassembly, cleaning, and reassembly of the Mikuni carburetor, including jetting specifications and tuning advice.
Depth:
Comprehensive, covering from basic maintenance to complete engine and transmission overhauls, including diagnostics.
Diagnostic Charts:
Includes comprehensive troubleshooting flowcharts for common starting, running, and performance issues.
Torque Specifications:
All critical fasteners and engine components have specified torque values for accurate assembly.
Clearances And Tolerances:
Provides precise measurements for piston-to-cylinder wall, ring gap, bearing clearances, and other critical tolerances.
File Type:
PDF (common for digital manuals)
Searchability:
Likely text-searchable if it's a well-produced PDF.
Printability:
Designed for printing of individual sections or the entire manual.
Binding:
N/A (for digital format) - If printed, typically spiral-bound or comb-bound for lay-flat use.
Paper:
N/A (for digital format) - If printed, would be heavy-stock paper suitable for workshop environments.
Type:
Liquid-cooled, 2-stroke, Reed valve induction
Bore X Stroke:
56.0 x 50.7 mm
Compression Ratio:
8.7:1 (typical for the era)
Cylinder Arrangement:
Single-cylinder
Cooling System:
Liquid-cooled
Horsepower Approx:
30-35 HP (estimated, peak power)
Torque Approx:
18-20 lb-ft (estimated)
Carburetor:
Mikuni VM28SS (typically)
Fuel Type:
Unleaded gasoline with 2-stroke oil mix (e.g., 20:1 or 32:1 depending on oil type)
Type:
Premix (fuel and oil mixed) and separate oil injection for transmission
System:
CDI (Capacitor Discharge Ignition)
Oil Change Interval:
Every 5-10 hours of riding, or as specified in the manual for gearbox oil.
Air Filter Cleaning:
After every few rides or when visibly dirty.
Chain Maintenance:
Lubrication and tension adjustment every 5-10 hours of riding.
Spark Plug Replacement:
Periodically, or as recommended based on performance checks.
Top End Rebuild:
Depending on usage intensity, typically between 20-50 hours of hard riding.
Transmission Oil:
Yamalube Gear Oil (or equivalent SAE 10W-30 API SE/SF, API GL-4 transmission oil). Capacity: 0.65 L.
Coolant:
Mixture of water and permanent antifreeze (ethylene glycol based) with a specific gravity of 1.047.
Brake Fluid:
DOT 3 or DOT 4 brake fluid.
Common Wear Items:
Clutch plates, piston and rings, chain and sprockets, wheel bearings, brake pads.
Carburetor Clogging:
Can occur due to fuel degradation or debris if not properly maintained.
Suspension Seals:
Fork seal leaks are common with hard use.
