Oil Starved Engine Disassembly.

ashman said:

Throw the motor in a drum of Kero for a week or 2.

Click to expand...

Best idea yet, patience is the key.

If you think it is rust that is sticking the pistons, Try soaking with Evap o Rust. I soaked some Dunstall muffler ends to free up the nuts that hold the baffles in, after a few days they suddenly were "finger tight" and came out with no effort.

Considering the condition of the engine, you are probably not loosing much if you cut the studs off, then split the cases. You may still end up cutting the pistons though. A previous comment about possible stretching the rods should also be considered.
What are you actually trying to save here though? The crank may be usable, but the cam and lifters are also probably damaged, the rods are suspect, as are the bearings. The valve gear will need careful inspection as well. To judge from the photo of the front sprocket, there's probably not a lot of usable bits left on this engine & gearbox.

Seems like a lot of work to avoid simply sourcing a better example from Fleabay or similar.

Update - I managed to remove the cylinders by cutting off the tops of the pistons using a door handle cutter (thank you Grandpaul) them ground through the walls of the piston skirts with a dremel. A long, dirty hard job but it’s all apart now. Note to self- never buy another project with a locked up motor caused by oil starvation. This is on me as I looked inside the oil tank when I was viewing the bike and saw no oil present. I thought - that’s weird.