Yep, I got em, same thing. I am very disapointed in them.
+1 So I ditched em. Junk at half the price. The "2 stroke" cable cam which we Duc folk use is the culprit, its made of too soft pastic which wears so that the cam can rotate (and stick slightly) beyond the normal throttle stop.
At 0 throttle, i can push BACK a little bit and it seems to get caught on one of the teeth (teeth on grip hooked in to throttle)
I have a brand new spare Rizoma "2 stroke" throttle cam, PM me your postal address and its yours.