I suggest you pull off the clutch cover (right side of the engine) and have a look. It shouldn’t be like that so you may have some worn parts. The other thing to do is adjust the air gap on the throwout arm, which can be accessed by the centre plug on the clutch cover.
The kart looks like a reasonably nice unit. That said, and not wanting to start a big debate about it, I’m going to suggest that unless you have your heart set on a 250F you’d be happier picking up a 125.