aprilia rally 50md only drives max.15km/h o_O

Hi Community I signed up for my scooter earlier, which was only around for a while, was not in operation this year at all. Recently, however, he was inside the workshop, I had to change the battery, otherwise everything was supposed to be tiptop. Now this is the following: Now I’m off and it always went out when I stop. As far as I remember, this is because it has not been used for some time now?!Otherwise he drove normally, but he has reached his 50km/h. That the Ro It was always like this when he started driving a little bit delayed, but then it took about 3-4 seconds until he pulled on and went on normally, then the next traffic light was over. Turning the gas had no effect any more, he didn’t hit. ALso on the sidewalk, stand out and try it like that. Then it went, the rear wheel accelerated, albeit somewhat delayed, quite normal and the scooter got quite loud. Again, and on the road drove again. He tried everything possible for me on a parking lot (I can’t do anything but not too much), but he was faster than 15km/h on a straight track with full gas. Hope it was reasonably understandable^^ Btw: isn’t automatic scooter I thought about the centrifugal force coupling first, but then the wheel shouldn’t turn fast without load, wouldn’t it?! Would it be great if you were May help me Best regards, Marian