Hyosung GT650 Comet Service Manual (2004)

Hyosung developed the GT650 as the largest member of its road-going GT family and brought the naked 650 into production for the 2004 model year. The motorcycle represented an important step beyond Hyosung's smaller commuter and 250-class machines: it used a 647 cm³ liquid-cooled 90-degree DOHC V-twin in a steel twin-spar-style chassis, giving the company a direct entry into the middleweight roadster market. Period specifications list the 2004 GT650 with the same 1,435 mm wheelbase, 17-litre fuel tank and 17-inch radial tires documented in the factory workshop source.

The Comet name was used for the GT road-bike family in a number of export markets. In its original naked form, the 650 combined upright handlebars with dual front discs, a 120/60-ZR17 front tire and 160/60-ZR17 rear tire, giving it a more sporting roadster layout than Hyosung's Aquila cruisers. The early engine used twin BDSR39 carburetors, a six-speed gearbox and chain final drive. That configuration made the bike a carbureted 650 cc V-twin roadster aimed at riders who wanted middleweight performance with a relatively simple mechanical package.

The GT family broadened soon after launch. By 2005 Hyosung had added the half-faired GT650S and fully faired GT650R around the same 647 cm³ V-twin platform. Rider Magazine's GT650S road test documents that shared engine architecture and describes the carbureted V-twin as the common powerplant for the GT650S, GT650R and GV650. Those derivatives changed riding position, bodywork and some chassis details, while the naked GT650 remained the simplest expression of the platform.

The family continued to evolve through the late 2000s and early 2010s. Electronic fuel injection eventually replaced the twin-carburetor setup, and Hyosung later revised styling, electronics and suspension. Cycle World's 2013 Hyosung buyer's guide records a later generation using Delphi fuel injection and upgraded suspension, providing a clear technical separation from the carbureted first-generation motorcycle documented here.

This listing is tied specifically to the original naked GT650 factory publication. Hyosung Motors & Machinery Inc. Service Manual No. 99000-94810 carries a 2003 copyright and is marked “2nd Ed. JUN. 2004.” Its specifications cover the naked 647 cm³, twin-carburetor, six-speed, chain-drive machine; later S/R variants used additional factory supplements. Because this source does not explicitly state 2002-2005 applicability, catalog coverage is conservatively limited to 2004. Related publications are grouped in the Hyosung GT650 manual catalog.