Scooter is very difficult to start?

Hi, my tuned Gilera Runner C46 with 70 cc is very hard to start after 20 or 30 kicks. I recently bought it on eBay, the seller couldn't tell me anything about the tuning, so he didn't know what was installed. Only that the Runner 70 cc, 17 hp, 17 mm carburetor and everything else is tuned. And also a Yasuni exhaust. It's a 1:50 self-mixer with a fuel tap. If I open the fuel tap, wait a bit (5 minutes) and then kick it, it always takes about 30 kicks before it starts. What could be wrong? I haven't done anything to it yet. Can anyone help?
Thanks in advance 🙂