You mean to say that clutch box opened while it was running? Or it wasn't clutching and hence it has to be opened?
I never had any issue with clutch box tried both stock and 3 plate qingqi complete box with primary and secondary gears of qingqi.
Check if clutch box is within service limits. Honda manual for any c70 explains it.
Also clutch plates needs to be kept in engine oil for 24 hours before installing them in bike.
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