Doubt is should be necessary to return the entire engine to China
Please shoot a few more photos, especially of the head/top end of the engine, would like to know if anything else i bent/broken.
First off, going by your picture, i assume your engine is a M90 like mine here?
As far a taking it down, i really haven´t had much need to do so, but have fettled a bit none the less...so if i´m right in my assumption, i believe that you´re set if you have a 2.5mm hexkey.
Now that the valverod is already gone, just insert the hexkey as in the picture below and loosen that screw.
Don´t think you have to remove it completely, but that way you can move the sprocket outwards towards the flywheel, leaving just enough room for you to remove the part in question.
(Just did it on mine to test, and that still has the fullsize bearing on there.)
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