I drive a Benzhou YY50QT-31 with 4-stroke 139QMB engine. A 10 cm long nail (!!! beware of your neighbor) in the rear tire forced me to screw on my scooter the other day. When washing off I also opened the Variomatik lid… and found no ring on the Variomuff. Well, then I tracked the cable from the speed sensor and found a plug connection on the way to CDI, for example under the carburetor. After I released this not much happened as long as the scooter was on the main stand . During the ride I noticed that the engine reached at low speeds (30-40 km/h) about 6000 rpm. But then on a flat road it pulled up to 60 km/h at about 6500 rpm. Can anyone explain that to me? The CDI-Rossel is in!