TOPIC:

I'm with Wookie on this.  Pull your engine apart and see what the bottom end and transmission look like. 

That #1 cylinder is downright nasty!  You have a couple of options.  There is a sleeve inside the aluminum cylinder block.  It can be replaced.  Or you can buy a used block.  Or you can bore your cylinders.  If you bore them the extent will be determined by the corrosion in #1.  First bore over standard is a half mm.  Second is a full mm.  The other cylinders look used but not abused.

Shims sit on top of the buckets.  Try to keep them together and try to keep the buckets so that you can replace them from the valve they came from, but it's not essential.

Would it be unusual to not have shims?  I see nothing on top of the buckets, nor do they have an indentation to hold them, as it looks like the case on page 15, illustration B12 of the PDF manual TexasKZ included.  I'll get the rest of the buckets out and see what I find.
I don't think the PO tried to turn over the motor after it had been sitting.  This came from a guy that had tons of bikes when he died.  I think it was originally going to be pulled out of the frame as many of the mounting bolts had been removed or loosened.

What's the best way to break that piston loose?  Lift the block and tap down on the pistons? I had put oil in it before I started this process.  Hopefully, some of it found it's way below the piston.

Those cylinders look big. Measure them and let us know. Be careful trying to remove that piston. I've been using Ed's concoction of ATF and acetone for things like this. You pour some it and it bubbles it's way through the rust. If you can raise the block off the case you can install a couple wood shims to hold it up while you tap on the piston with a block of wood and a mallot. Take your time and it might come out without having to drill it out.   
I saved this one and am using it now after porting it  along with other things.
Steve

Would it be unusual to not have shims?  I see nothing on top of the buckets, nor do they have an indentation to hold them, as it looks like the case on page 15, illustration B12 of the PDF manual TexasKZ included.  I'll get the rest of the buckets out and see what I find.
I don't think the PO tried to turn over the motor after it had been sitting.  This came from a guy that had tons of bikes when he died.  I think it was originally going to be pulled out of the frame as many of the mounting bolts had been removed or loosened.

What's the best way to break that piston loose?  Lift the block and tap down on the pistons? I had put oil in it before I started this process.  Hopefully, some of it found it's way below the piston.

It must have shims either "over" or "under" the buckets - this is the only way to adjust the valve clearances as "hydraulic lifters" aren't an option. If they aren't on the top it may have been fitted with under shims and buckets at some point (they will be small shims on top of the valve stems - or stuck to the underside of the buckets)
As Steve has said soak the rusty piston and take your time, if the rings where any good then most of the water will have been contained above the piston so hopefully below the rings won't be too bad which should allow you to knock the piston downwards (it can't be seized completely as you can rotate the engine approx half a turn which would suggest the sticking point was the band of rust above the piston, otherwise it would be completely frozen  )

Again, you don't know how much I appreciate your guidance and input.  I've been on sites that will start treating you like an idiot if they think your question is beneath them. 

What's the ratio of trans fluid to acetone, or just dump some of each in?  Luckily, I have both here at my house.

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Again, you don't know how much I appreciate your guidance and input.  I've been on sites that will start treating you like an idiot if they think your question is beneath them. 

What's the ratio of trans fluid to acetone, or just dump some of each in?  Luckily, I have both here at my house.

The sad part is often the people that display that level of arrogance don't actually know as much as they think they do 

wrote:

wrote:

Again, you don't know how much I appreciate your guidance and input.  I've been on sites that will start treating you like an idiot if they think your question is beneath them. 

What's the ratio of trans fluid to acetone, or just dump some of each in?  Luckily, I have both here at my house.

The sad part is often the people that display that level of arrogance don't actually know as much as they think they do 

There are no stupid questions, only stupid answers....

So now that the head is off , have you tried to spin the crank ?
I see the photos show pistons 2 and 3 at top dead center.
Likely the corrosion is above the piston rings.
With some luck the cylinder may be able to be removed  with some tlc
Dave

wrote:

Again, you don't know how much I appreciate your guidance and input.  I've been on sites that will start treating you like an idiot if they think your question is beneath them. 

What's the ratio of trans fluid to acetone, or just dump some of each in?  Luckily, I have both here at my house.

50/50    If you can get them to move then add more wood blocks until you can pull the barrels free. Don't pound on it if the crank is at bottom dead center. Hopefully water didn't get past the rings. Did you measure the holes? Looks like big bore pistons to me. If so used barrels and pistons would work or stock barrels bored to 1045/75 could make a good runner if the crank isn't shot. 

Steve
 

Can you post a photo of your buckets?  If they are round and smooth on the top they were probably converted at some point to shim under bucket.  If they have an indent on the top and a small insert near the outside diameter they are shim over bucket.  

1:1 acetone to atf

No technical advice here as others have you covered, but I was told early on the only stupid questions are those you don’t ask.