Engine Mechanical:
Detailed breakdown, assembly, component testing, specifications for the 125cc two-stroke engine.
Engine Fuel System:
Carburetor tuning, fuel pump, fuel lines, fuel tank maintenance.
Engine Ignition System:
Ignition timing, spark plug specifications, CDI unit, stator, coil testing.
Cooling System:
Radiator, hoses, coolant specifications, water pump maintenance.
Exhaust System:
Expansion chamber, silencer maintenance and repair.
Transmission Gearbox:
Gearbox inspection, repair, gear ratios, shifting mechanism.
Clutch System:
Clutch type (likely cable-actuated), clutch plates, springs, operation.
Chassis Frame:
Frame inspection, geometry, general integrity.
Suspension Front:
Upside-down telescopic forks, adjustment, seals, oil, internal components.
Suspension Rear:
Monoshock absorber, linkage system, adjustments, maintenance.
Brakes Front:
Hydraulic disc brake system, caliper, master cylinder, rotor, pad replacement, bleeding procedure.
Brakes Rear:
Hydraulic disc brake system, caliper, master cylinder, rotor, pad replacement, bleeding procedure.
Wheels Tires:
Wheel bearing maintenance, tire replacement, rim specifications, spoke tension (if applicable).
Electrical System:
Wiring diagrams, battery, lighting, horn, switches, fuses.
Bodywork Panels:
Fairings, fenders, seat, fuel tank removal and installation, graphics.
Controls Cables:
Throttle cable, clutch cable, brake lever adjustment, handlebar controls.
Routine Maintenance:
Oil changes, filter replacements, chain adjustment, lubrication points, general inspections.
Engine Rebuild:
Top-end rebuild (piston, rings, cylinder), bottom-end rebuild (crankshaft, bearings).
Troubleshooting:
Diagnostic flowcharts, common problem identification and solutions for various systems.
Component Disassembly Assembly:
Step-by-step instructions for removing, disassembling, inspecting, and reassembling all major components.
Suspension Servicing:
Fork seal replacement, fork oil change, shock absorber service.
Brake System Service:
Brake fluid replacement, caliper overhaul, bleeding procedures.
Carburetor Overhaul:
Complete disassembly, cleaning, jetting, and reassembly of the carburetor.
Electrical Diagnostics:
Testing of electrical components, wiring continuity checks.
Depth:
Comprehensive (covers everything from basic maintenance to full engine and chassis overhauls)
Diagnostic Focus:
Strong emphasis on diagnosis and repair of common issues for the era.
Specifications Detail:
Includes detailed torque values, tolerances, clearances, and fluid capacities.
Engine Type:
Liquid-cooled, two-stroke, single-cylinder
Bore X Stroke:
Likely around 54mm x 54.5mm (typical for this displacement and era of Husqvarna 125cc engines, e.g., CR 125).
Displacement:
123.73 cc (approx.)
Compression Ratio:
Likely in the range of 8.0:1 to 9.5:1, depending on specific tuning.
Reed Valve System:
Likely has a reed valve induction system.
Horsepower Estimated:
Typically 25-30+ HP for street-legal versions of 125cc two-strokes of this era, higher in competition tune.
Torque Estimated:
Estimates around 18-22 Nm (Newton-meters) depending on gearing and peak power RPM.
Carburetor Type:
Likely a high-quality carburetor from Dell'Orto (e.g., PHBH 28/30mm) or Mikuni.
Fuel Type:
Unleaded gasoline (95 RON or higher recommended)
Fuel Mixture:
Requires pre-mix of gasoline and two-stroke oil (typically 50:1 or 32:1 depending on oil quality and usage).
Oil Change Engine:
Transmission oil: every 10-15 hours of use or annually. Pre-mix ratio is critical.
Spark Plug Check:
Check/clean every 5-10 hours, replace every 20-30 hours or as needed based on condition (e.g., NGK BR8EG is common).
Air Filter Cleaning:
Clean after every 5-10 hours of dusty riding, or monthly. Replace as needed.
Chain Lubrication Adjustment:
Lubricate every 500-800 km, adjust chain slack every 1000 km or as needed.
Transmission Oil:
API GL-4 or GL-5 SAE 75W/90 synthetic gear oil (check manual for exact spec).
Coolant:
Ethylene glycol-based antifreeze mixed with distilled water (typically 50/50 ratio).
Brake Fluid:
DOT 4 hydraulic brake fluid.
Fork Oil:
Likely SAE 5W or 10W suspension fluid (specific weight crucial for handling).
Two Stroke Oil:
High-quality, JASO FD or ISO-L-EGD certified full synthetic two-stroke oil.
Two Stroke Top End Wear:
Two-stroke engines are susceptible to piston and ring wear; regular top-end rebuilds are standard maintenance.
Carburetor Tuning Sensitivity:
Carburetor jetting can be sensitive to altitude, temperature, and exhaust modifications.
Electrical Connections:
Corrosion or loose connections in the electrical system can lead to intermittent issues, especially after off-road use.
Suspension Seals:
Fork seals and rear shock seals can wear over time and require replacement.