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Hyosung GT125 & GT250 Series Resources

The Hyosung GT series is the most popular range in the lineup, spanning the naked GT125/250 Comet, the faired GT125R/250R, and the modern RC/P facelifts. As these bikes are very common across the UK and EU, we have preserved these official workshop manuals and owners books to ensure access for the community.

Model Identification & Technical Data

Whether you are tuning carburettors on a Gen 1 silver-engine model or diagnosing a Delphi EFI system on a newer black-engine 250cc, identifying your generation is key:

GT125/250 (1998–2008): Silver engine, Mikuni Carbs, “Old Shape” (Gen 1).
GT125/250 RC & P (2009+): Black engine, Facelifted bodywork, Carburetted or EFI.
EFI Models (2008+): Features an O2 sensor in the exhaust downpipe and 28hp DOHC V-Twin engines.
Maintenance: All models feature the iconic 75° V-Twin DOHC 8-valve architecture.

For more details, see our Pre-2009 (Gen 1) Wiki or the Post-2009 Facelift Gallery.

Carburetted (Carby) Models

Electronic Fuel Injection (EFI)

Need Help? If you have technical questions, please visit the Technical Help Forum.

Hyosung GD250N & GD250R (Exiv) Resources

The Hyosung GD250 series (known as the Exiv or X-5) represents KR Motors’ bold move into the lightweight single-cylinder market. Though discontinued in 2018, these “thumpers” maintain a strong cult following thanks to their mass-centralised design and punchy performance. Whether you ride the naked GD250N or the fully-faired GD250R, the technical documentation below is essential for maintaining these high-compression singles.

GD250 Series Technical Specifications

Both the N and R variants share the same liquid-cooled, fuel-injected engine platform. The GD250 is famous for its under-slung exhaust and 50:50 weight distribution. Essential maintenance data includes:

Engine: 249cc Single Cylinder, DOHC, 4-Valve, Liquid-Cooled
Power: ~28hp @ 9,500 RPM | 24Nm Torque
Fuel System: Electronic Fuel Injection (EFI)
Oil Capacity: 1.3L to 1.5L (10W40 Semi-Synthetic)
Brakes: 300mm front disc with 4-piston radial caliper

For detailed photo galleries and full parts breakdowns, visit our GD250N Naked Wiki or the GD250R Sports Wiki.

⬇ GD250N / R OWNER’S MANUAL

⬇ GD250 SERIES WORKSHOP MANUAL

Notice: The service manual provided above applies to both the Naked and Sports models as they share the same engine, frame, and electrical architecture. If you notice any missing technical data, please contact the Admin.

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[Download] Hyosung GT125 & GT250 (Comet/R/RC) – Service Manuals & Owner’s Books