I have give this some thought for several years now and finally made up my mine to make my own 55 CC engine. So far I have the front case half about finished. I still need to radius a few places. The rest of the material is on order for the back half. Since I don't have a CNC milling machine there are just some things that is not feasible to do with a conventional mill W/O making some very elaborate setups, so I decided to keep it somewhat simple. I'll post pics as things progress. I used a DL-50 for the mule but I will be making several changes to things.
I may go with the 55 DL cylinder and piston, not sure yet. Since one of the changes is the crankshaft I will make my own crankshaft & rod.