The GK125 takes the neo-retro styling of the larger GK350 and scales it down for A1 and car-licence riders - scrambler proportions with a café racer edge. The engine is the shared liquid-cooled 125 single at 14.5 hp at 9,000 rpm and 13 Nm at 7,000 rpm, with a slipper clutch and ABS. Dry weight is 143 kg and seat height 790 mm, which keeps it accessible across rider sizes. The headline number, though, is the tank: 17 litres on a 125, which combined with this class's low consumption gives seriously long range. The GK125 X is the same bike with spoked wheels for a more retro look.
The screen problem, inherited
The GK125 shares more than styling with the GK350 - it shares its main weakness. Owners of the 350 consistently report that sustained speed without wind protection is the model's worst trait, and the 125 has the same upright bar and exposed stance. A flyscreen or small sport screen is the highest-impact purchase on this bike, and it sits at the top of this collection for that reason.
The rest, and one buying note
After the screen: tail racks and soft luggage, because a 17-litre tank turns this into a genuine weekend machine; then hand guards, engine and radiator protection, wide footpegs, bar-end mirrors and grips. The dash is LCD with tyre pressure monitoring including a puncture alarm and a trip computer showing both average and instant consumption, and the bracelet smartkey works even when the battery is flat, so electronics upgrades add little. One buying note specific to the X: spoked wheels change what tyre and valve products apply, and inner tube requirements differ from the cast-wheel standard model. Check which version you have.
Fitment
Covers the ZT125-GK, the "GK125" naming used in Spain and by UK dealers, and the GK125 X trim. Engine and control parts frequently interchange across the Zontes 125 range including the 125U, 125Z2 and 125G1. Wheels, bodywork and rack mounts are GK-specific, and cast versus spoked differs between GK125 and GK125 X.