Oil Starved Engine Disassembly.

I could use some advice. I have an 850 motor that ran out of oil and seized. The pistons are stuck in place at nearly TDC. I am trying to get the cylinders off the crankcase so I can separate them and unbolt the connecting rods. However, the position of the pistons prevents the cylinders from clearing the crankcase halves. I have tried everything imaginable to push the pistons down but they have galled and seized solid in the cylinders. A mix of diesel and acetone doesn’t move them. I believe I need to collapse the piston by drilling holes in the crown. Has anyone tried this before and can they provide any advice?

Not clear what methods have already been used, but I would pack timber between the cylinders and crankcase, heat the cylinders, and whack the pistons with hammers of increasing sizes…..
Other method could be to clamp a bar across the cylinders with sockets or something between that and the cylinders. Put some strain on, then hit with a hammer….

DougC said:

Not clear what methods have already been used, but I would pack timber between the cylinders and crankcase, heat the cylinders, and whack the pistons with hammers of increasing sizes…..
Other method could be to clamp a bar across the cylinders with sockets or something between that and the cylinders. Put some strain on, then hit with a hammer….

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Thanks Doug but I’ve tried all those. I welded up a clamp bar and applied beaucoup pressure via a couple of 5/8” bolts. I went through numerous heat cycles and got medieval with a block of wood and a sledge hammer. I’ve only ever seen this level of seizure with a H2 750 two stroke that locked up due to oil starvation.

Oh well..
How about a hole saw to cut out most of the piston crown? Not sure if that would cut the gudgeon pins as well, or if they're hardened.
That might allow the lower half of the piston to break off and get forced down..

Yorkie said:

Thanks Doug but I’ve tried all those. I welded up a clamp bar and applied beaucoup pressure via a couple of 5/8” bolts. I went through numerous heat cycles and got medieval with a block of wood and a sledge hammer. I’ve only ever seen this level of seizure with a H2 750 two stroke that locked up due to oil starvation.

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was it a anti-sump valve that caused the oil starvation? Just curious.

The pistons can be drilled & cut out. Do you know a talented fabricator?

concours said:

was it a anti-sump valve that caused the oil starvation? Just curious.

The pistons can be drilled & cut out. Do you know a talented fabricator?

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Utter neglect was the source of the oil starvation. Here is the front sprocket that tells the whole story.

Yorkie said:

Utter neglect was the source of the oil starvation. Here is the front sprocket that tells the whole story.

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If that bike was a human or an animal, someone would be headed to jail.

Looks like it was pulled out of a dried up wash in Death Valley CA.

As far as getting the barrels off the pistons goes. I'd bolt the crankcases back together in a bolted down engine stand, then start the hammering, heating, or whatever technique one prefers. It would prevent potential binding of parts not aligned properly and the hammering would be more effective. That is what my brain is telling me. That said I have only worked on locked up V8's and not any locked up motorcycles that I can remember.