Positioning:
Aimed at DIY enthusiasts and independent workshops looking for detailed technical guidance for Hyosung GT125 and GT250 Comet motorcycles.
Competitors:
Official Hyosung service manuals, Haynes, Clymer, and other aftermarket repair guides. This manual offers a digital, accessible format.
Diy Focus:
Designed to empower owners to perform maintenance and repairs, saving on labor costs and fostering mechanical understanding.
Diagrams:
Includes step-by-step diagrams for clarity during complex procedures.
Tool Incentive:
Encourages tool acquisition as part of the DIY experience.
Engine:
Detailed overhaul, inspection, and repair procedures for engine internals, lubrication, and cooling systems.
Gearbox Clutch:
Clutch operation, adjustment, and replacement; gearbox disassembly, inspection, and repair.
Cooling System:
Radiator, fan, thermostat, coolant circulation, and pressure testing.
Fuel System:
Carburetor (or EFI if applicable), fuel pump, fuel lines, fuel tank maintenance, and fuel filter replacement.
Braking System:
Front and rear brake caliper overhaul, brake pad replacement, brake fluid bleeding, master cylinder service, and hydraulic system troubleshooting.
Suspension:
Front fork (telescopic) disassembly, seal replacement, oil level/viscosity specifications; rear shock absorber inspection and replacement.
Electrical System:
Wiring diagrams, battery maintenance, charging system (stator, regulator/rectifier), ignition system (spark plugs, coils), lighting, and starter motor.
Body Fixtures:
Fairing removal and installation, seat adjustment, paneling, and accessory mounting.
Exhaust System:
Exhaust pipe and muffler inspection, gasket replacement, and secure mounting.
Wheels Tyres:
Wheel bearing inspection and replacement, tire pressure specifications, wheel balancing, and rim maintenance.
Maintenance:
Scheduled maintenance tasks, oil changes, filter replacements, chain adjustment, and general upkeep.
Troubleshooting:
Diagnostic procedures for common faults and performance issues across all major systems.
Repair:
Step-by-step instructions for component disassembly, repair, and reassembly.
Technical Data:
Torque specifications for all fasteners, fluid capacities, clearances, and electrical resistance values.
Depth:
Comprehensive, covering basic maintenance to full engine and gearbox rebuilds.
Gt125 Engine Type:
Likely a V-twin liquid-cooled, 4-stroke engine.
Gt250 Engine Type:
Likely a V-twin liquid-cooled, 4-stroke engine.
Gt125 Displacement:
Approximately 125cc
Gt250 Displacement:
Approximately 250cc
Horsepower Gt125:
Typically in the 15-18 HP range (subject to market variations and tuning).
Horsepower Gt250:
Typically in the 25-28 HP range (subject to market variations and tuning).
Fuel Delivery Gt125:
Typically carbureted, often with dual Mikuni or similar carburetors.
Fuel Delivery Gt250:
Typically carbureted, often with dual Mikuni or similar carburetors. Later models might feature Fuel Injection.
Engine Internal Components
Valve Clearance Specifications:
Manual will provide specific intake and exhaust valve clearance figures (e.g., 0.05-0.10mm).
Oil Type Recommendation:
Typically SAE 10W-40 or 20W-50 API SG or higher motorcycle-specific oil.
Oil Capacity:
Will vary by model, but generally around 1.5-2.5 liters with filter change.
Transmission Type:
Constant mesh, 5 or 6-speed manual transmission.
Gear Ratios:
Manual will detail primary drive and individual gear ratios for optimized performance.
Clutch Type:
Wet, multi-plate clutch.
Clutch Fluid Type:
If hydraulic: DOT 3 or DOT 4 brake fluid.
Transmission Oil Type:
Motorcycle-specific gear oil, or as specified by Hyosung.
Gt125 Dimensions:
Length, width, and height details will be present in the manual.
Gt250 Dimensions:
Length, width, and height details will be present in the manual.
Gt125 Dry Weight:
Typically around 150-160 kg.
Gt250 Dry Weight:
Typically around 170-180 kg.
Front Tyre Size:
Commonly 110/70-17 for GT250R, similar for GT125 variants.
Rear Tyre Size:
Commonly 150/70-17 for GT250R, similar for GT125 variants.
Wheel Bolt Pattern:
N/A for typical motorcycle spoke or cast wheels; uses axle mounting.
Recommended Tyre Pressures:
Manual will specify front and rear pressures (e.g., 28-32 PSI).
Safety Ratings:
As this is a service manual, official crash test ratings for motorcycles are not typically provided. Focus is on safe repair practices.
Braking System Type:
Front and rear disc brakes, typically hydraulic actuation.
Frame Type:
Likely a steel trellis or diamond frame for structural integrity.
Brake Fluid Spec:
DOT 3 or DOT 4 (check manual for specific Hyosung recommendation).
Instrument Cluster:
Typically features analog tachometer, speedometer, fuel gauge, and indicator lights. Digital displays may vary by trim.
ABS Availability:
ABS may be optional or standard on later models, but not guaranteed across all variants.
Usb Charging:
Generally not a standard feature on these models, but aftermarket solutions exist.
Oil Change Interval:
Typically every 3,000-6,000 km or 6-12 months, whichever comes first (refer to manual).
Spark Plug Replacement:
Approximately every 10,000-15,000 km, depending on plug type.
Chain Lubrication Adjustment:
Recommended every 500-1,000 km or after riding in wet conditions.
Engine Oil Viscosity:
SAE 10W-40 or 20W-50 is common for V-twin engines.
Coolant Type:
Ethylene glycol-based, anti-freeze/anti-corrosion coolant (usually 50/50 mix with distilled water).
Carburetor Tuning:
Carburetors may require periodic synchronization and adjustment for optimal performance.
Electrical Connections:
Checking and cleaning electrical connectors can prevent intermittent issues.
Torque Specifications:
Critical torque values for engine bolts, suspension components, and wheel fasteners are provided.
Manufacturer:
Hyosung Motors & Heavy Industries, a South Korean manufacturer.
Gt Series Development:
The GT series represents Hyosung's effort to produce sportbike-styled motorcycles for various engine capacities.
Production Period:
The GT125 and GT250 models have been in production for many years, with updates and variations across different model years.
Gt Variants:
Includes standard naked versions, faired sport versions (GT125R, GT250R), and potentially cruiser variants.
