The Hyosung GT125 is a 125 cc naked motorcycle that the South Korean firm built from 2001 to 2016. It belonged to the Comet series, which also included 250 and 650 cc variants, and all of them shared the same V-twin engine architecture.
Hyosung GT125 at a glance
| Maker | Hyosung Motors, South Korea |
|---|---|
| Production | 2001–2016 |
| Capacity | 124 cc |
| Engine | DOHC V-twin based on Suzuki designs |
| Body styles | naked Comet and fully faired GT125R |
| Chassis | shared with the GT250 |
| Family | Comet, with 250 and 650 cc versions |
| Known weakness | flat spot between 6,500 and 10,500 rpm before the 2006 engine change |
| Service point | valve clearance every 6,000 km |
Based on one source, the English Wikipedia article on the GT125.
History of the Hyosung GT125
The GT125 arrived in 2001 as the smallest member of Hyosung’s Comet family. It came in two body styles: the fully faired GT125R and the unfaired naked version sold as the Comet. Both used a 124 cc double-overhead-camshaft V-twin derived from Suzuki designs, mounted in the same chassis as the larger GT250.
Using the bigger bike’s frame gave the little Hyosung a build quality that stood out in the learner class — Motorcycle News called the GT125R “way above average for the budget 125cc class” — but it also made the machine heavier than the single-cylinder 125s that most beginners rode. The V-twin layout was unusual at this capacity, where almost every rival used a single.
Owners commonly fitted a carburettor ‘kit up’, usually costing around €100, to improve the air and fuel mixture. It was meant to smooth over the engine’s well-known lack of torque between 6,500 and 10,500 rpm. That flat spot applied to models built up to 2006, after which the engine design was changed to remove it; the problem is still reported on later bikes, but can be dealt with by setting the valve clearance correctly every 6,000 km.
Design and features
- V-twin in the 125 class: a 124 cc DOHC twin where most rivals used a single.
- Two versions: the faired GT125R for riders who wanted a sports look, and the naked Comet.
- GT250 chassis: strong and well finished, but heavier than a typical learner 125.
- Carburettor tuning: a popular ‘kit up’ to improve fuelling, especially on pre-2006 bikes.
Hyosung GT125 versions
- GT125R: fully faired sports version.
- GT125 Comet: naked version without fairing.
- Pre-2006 models: the engine with the pronounced flat spot between 6,500 and 10,500 rpm.
- Post-2006 models: revised engine design intended to remove the flat spot.
The GT125 shared its chassis with the GT250 and its engine family with the larger GT650. More models are in the Hyosung collection.
Sources
- Hyosung GT125, English Wikipedia: production, body styles, engine, chassis, carburettor tuning
