'79 H Model Pistons

Does anybody know if other pistons other than the specified pistons in the '79 KZ400 H parts diagram (Standard piston: #13001-1001) will fit into a '79 KZ400 H? I've come to the conclusion that I am going to have to beat the bejeezus out of them to get them out of the jug and will probably need a replacement - or two. 

I have tried heat, diesel and ATF,  packing the cylinders with a grease gun and squeezing (making a big mess since the valves weren't sound), a big wooden dowel and BFH, harsh language and any combination of the above. I am open to ideas. While I don't want to get Medieval on its ass with a sledge and a length of pipe, a combination of Life and this bike fighting me at every turn makes it more and more appealing...It's taken some blood from ME, and I'm beginning to get to the point where I just don't care how much I hurt it, and that could be some good therapy for me.

What I'm wondering is, even though the parts diagram says the (Standard) part number is 13001-1001; this bike was made over several years and I can't imagine Kawasaki went to great lengths to change every bit of the engine - for instance, this size piston (I have yet to put the calipers on it) may have been used in other years; can anybody confirm this, and maybe provide those part numbers? 

If you beat on it you're beating on the lower end too. Turn it to top dead center, use small blocks of wood to hold the barrels up then tap on the pistons one then the other back and forth watching for the pistons moving down. Looks like they're almost out. 

"Turn it to top dead center, use small blocks of wood to hold the barrels up then tap on the pistons one then the other back and forth watching for the pistons moving down.

Did that; but I'll give it a whack again - pun intended.  The pistons are frozen in their sleeves at BDC, btw...that dark area below the jug is the sleeve.

Well, victory is mine, I suppose. I was out working on the head today and got it to release the pistons, which are toast, as I suspected. I did jack it up as high as it could go and started first with a length of dowel I got from Lowes, but that turned into splinters real fast, so I cut a length of tree limb from a tree in the backyard that has really heavy wood, I'm not sure what kind it is but it's really heavy, dense wood. Went back in and took a 5 lb sledge to it and the pistons, beating it like it owed me money and finally got it to move and ultimately came out the bottom - so, yay:
  

Now I just have to get that dang sprocket cover off, which is rusted to the metal-lined seal around the shift shaft. 
   

The seal is rubber incased in steel. 
Steve

Yes, it is...which seems to have bonded at a molecular level with the shift-shaft. I don't have a proper oxy/acetylene blowtorch to heat it with and tried heating it with a propane torch, but I might as well have been using a Bic lighter. I did manage to dig the outer seal out, but according to the parts diagram there are TWO, one on the outside and one on the inside. The inside one is the one giving me problems - that sucker Will Not Budge, and I've been soaking it in PB Blaster for weeks now. It will not release, and I've already broken a chunk of the sprocket cover off trying to pry it from its rusty clutches. I am open to ideas.
 

Bringing this bike back is going to be a Job!

Well, some good news - I FINALLY was able to get the dang sprocket cover off; I went out to the garage and expected another fight, but the cover was able to slightly turn on the shaft, and I eventually wiggled it off, revealing the mess within:
 
The rest of it looks okay - 
 
...but if you look closely you can see the ring of PB Blaster'd rust around the inner seal - But I got it! Finally. 
 

It reminds me of the story of a guy who was trying to clear his field of a giant boulder. Every day he would go out and hit it with a sledge hammer until one day the rock split; and I wonder if it was THAT blow or all the ones that had come before...

In any event, I got it.
Drinks all around!
 

Hey mate, don't have any advice or suggestions for you but just found this post with your progress. Well done, having a drink for you right now lol.
Good luck with the rest of the project, looking forward to seeing more!

Hey, elfolan! Slainte!  Thanks for the shout-out, I look forward to seeing more too!

Re: the '76 KZ400 S - I have one of those too waiting in the wings...