Honda X8R accelerates badly

Hello guys and girls, I got a Honda X8R in parts from a neighbor about 2 years ago. After a bit of screwing and hemorrhaging I wanted to give the part of my daughter. Meanwhile he drives quite well but still has a serious problem, which I hope I can get rid of with your help. He starts well, turns well high in the stand (speed measured about 9000 rpm) and drives well on the first start. End speed is then over 45km/h (weight 100kg) . I couldn’t test it, however, because it still accelerates at the end of the settlement. Now the problem: if I stop at a crossroads until I stand, it no longer drives and the engine turns at the lower speeds but the scooter no longer accelerates. Do you have a tip on what this could be. The Vario and the converter are new, I now have weights 6 x 6g in it, but I had already tried 6 x 3.5g.