Posted by Chris Rushton "Guest"
I have dismantled quite a number of seized engines now, and it is surprising how little rust it takes to cause the pistons to seize in the bores - but then again, the clearance really is very small.
Assuming the whole motor is to be stripped, first strip the top end and remove the cylinder head (you may have to "split" the cam chain to get the camshaft out as with a seized motor you are unlikely to be able to remove by normal means the two bolts securing the cam sprocket to the camshaft).
Then, remove all side covers, etc, turn the motor over and split the crankcases. You can then remove the big-end caps, which allows the barrels to be removed from the upper crankcase with the pistons/ conrods still in them. If you are lucky, you may find that not all the pistons are seized in the bores. For any that are, I have often found that a couple of "hits with a hammer (using a substantial piece of wood against the piston top) may get them moving. In the worst cases, I have then had to resort to the use of a power press. I have always managed to get all four pistons out by this process without wrecking the barrels, even the one that took over 8 tons before it started to move. Sometimes of course the bores have been rusted to such an extent as to be scrap, but no matter, it is the alloy casting which is important (the liners can easily be changed).
Good luck!