Spacy CH125, cannot be adjusted

Hello, I have run a Honda Spacy CH125 scooter, built in 98, about 35,000 km. So far he has always provided good services, only the ignition box (CDI) under seat broke twice. Since I got no original ignition box anymore, I have built in a non original ignition box. This works well. The problem is that I can no longer adjust the stand gas reasonably, but here I already had problems with the original ignition box. I tried with the mixture scratch be able to get the engine reasonably to turn and then with the stand gas screw set the idling speed. After longer driving the engine goes out in the stand and then has problems to jump again. During the drive the engine runs really well. The carburettor was cleaned a few years ago by the specialized company (ultrasound). Do you have to replace parts in the carburettor, are there still original parts for the carburettor? Greeting Berni