Yong Heng vs look alikes - is there any difference?

There are subtle differences in the dimensions of the high-pressure pistons which make them not compatible in their respective cylinders. they also use different types of rings. It does seem possible to swap the whole top end around. even the fully enclosed Tuxing type assembly has the same bolt pattern as the Yong Heng exposed tube type. So yes they all use a common crankcase and motor but it is not recommended to mix up the top end internals.