Our shop has a special billet engine case for this size. It fits with this case without any modifications:
https://tunescoot.site/dio-50/cnc-case-180cc-dio50-af18-modification-blitz-by-bwsp.html
This size of cylinder can be used only with crankshaft 58mm:
https://tunescoot.site/dio-50/jiso-crankshaft-58mm.html