I'm not fully up to speed on this problem but I don't remember hearing of this issue before this latest batch of RX3 bikes from CSC.
I was wondering if perhaps a few of these newer bikes just have a bad batch of engines.
I get the impression that Zongshen are constantly revising components in this engine. An example of this is with my RX3 the countershaft sprocket is held on with a bolt rather than a nut. Yet my RX3, supposedly has the exact same engine as yours even though Its an 2014 model (UK).
Fortunately for me, my gearbox is fine
