Hyosung GT125 / GT250 Comet Service Manual (2002)

Hyosung began motorcycle production in 1978 through technical cooperation with Suzuki and gradually moved toward independently developed motorcycles. Hyosung's own corporate history records the creation of its motorcycle business in 1978, the Suzuki relationship, establishment of a technical research institute in 1986 and mass production of independently developed models from 1987. By the early 2000s that experience had expanded into a new generation of road motorcycles intended to move the Korean manufacturer beyond scooters, commuters and small trail bikes. Hyosung's corporate history provides that broader background.

The Comet family was part of that transition. The November 2002 factory publication groups the 125 and 250 together as closely related naked roadsters sharing the same 2,080 mm length, 1,455 mm wheelbase, 17-litre fuel tank, 17-inch tires and basic chassis layout. This gave both motorcycles the dimensions and visual presence of a larger machine rather than a lightweight commuter. The platform used twin-cylinder DOHC engines, dual disc brakes front and rear, a telescopic fork and swingarm rear suspension, creating a full-size small-capacity V-twin roadster platform that Hyosung could offer at two licensing and performance levels.

The GT125 occupied the learner and small-capacity end of that family. Its 124.7 cm³ V-twin used a 44 × 41 mm bore and stroke, twin BDS26 carburetion and a five-speed gearbox. Despite the small displacement, the factory chassis was essentially full-size, with the same 110/70-17 front and 150/70-17 rear tire sizes as the 250 and an unladen mass of 167 kg. Contemporary European coverage of the 2003 Comet 125 emphasized exactly that character, noting that the 125 shared its frame with the 250 and looked substantially larger than a typical learner-class motorcycle. Motoplanete's Comet 125 overview documents that market positioning.

The GT250 used the same concept with a 249 cm³ V-twin, 57 × 48.8 mm bore and stroke, five-speed transmission and heavier-duty 520 final-drive chain. In early 2003, Bikesales described the newly arrived Comet 250 as Hyosung's move into a more demanding road-bike segment after scooters, trail bikes and the Aquila cruiser, highlighting its combination of sports ability, value and full-sized road presence. Bikesales' 2003 Comet 250 road test captures how the model was received as Hyosung expanded into mainstream road motorcycles.

The Comet/GT line later developed into additional naked and faired derivatives, and the 250 family eventually moved to electronic fuel injection as part of Hyosung's later 250 cc range development. Those later motorcycles should not automatically be treated as identical to the first carbureted specification. This listing is tied to Hyosung Service Manual No. 99000-94710, marked “1st Ed. NOV. 2002,” which explicitly covers Comet 250 and Comet 125. Because the source itself does not state 2003-2005 applicability, catalog coverage is conservatively limited to 2002. Related factory publications are grouped in the Hyosung Comet manual catalog.