Somebody told me recently that the original Lifans which most of these seem to be copied from were originally measured and copied from an XL-XR100. If this is the case that may be an easier solution.

It seems the chinks never really copy anything, they just make it look like a copy, if it works fine, if not oh well.

I've seen at least 3 different types of these and none of them seem consistent in measurements or in the way they are assembled.