MZ/MuZ Riders

I have posted this question on other MZ related places.. so ignore if you have seen it there. gonna ask around before I do something drastic.. i bought a cheap motor, i knew it had suffered a seize but since i was only after a barrel and head to rebore to 300cc I sprung for it,

So i get round to cleaning it up, and had taken the head off, the piston is seized at the bottom of the bore, so i left it soaking in a mix of diesel, and light oil, and copious squirts of plusgas. so i made sure engines in neutral, and opted for the wooden baton and large hammer approach to try and free the piston from the bore. got it to move oh maybe 10mm as before the smaller ports on side were mostly covered, now i can see the bottom of them. still stuck solid though and i can't get the barrel off the studs.

Is there any other safe methods to let me get this motor split and the piston and crank removed, i want to check state of crank, and barrel before i send off for a new 301 piston and rings, and con rod and bearing kit for the crank so i can get it all sent off for rebore/crank rebuild. I really don't want to damage the barrel or crank. I don't want butcher anything in the process. as id like to rebuild this motor as a spare for my 250.

Drill around the edge of the piston just inside the rings, trying to join the drill holes and you'll be able to break away the ali allowing the rings to pulled out. The piston will be much easier to move.
Hope this helps

Hers one I did a few years ago on a Sachs 125 admittedly the piston is at the top. Go for a 6mm drill bit and just take your time.