Badly rusted piston - bore out or resleeve once removed?

Howdy, I took off the head to make removing a broken-off spark plug easier (I still can't get it out!) and found one piston badly rusted - as in, soaking in PB/lighting on fire/pouring boiling oil/hammering for hours hasn't budged it. The bike was sitting outside for about 5 years and the intake valve was open on #4.



Anyway, once I get it out, I assume the cylinder will be trashed. Should I have it bored out (potentially upsetting engine balance?), or resleeved (possibly more expensive?)

I'm also considering buying a new cylinder bank, or maybe another engine - but money's tight, as is always the case in these matters.

I'd appreciate your thoughts and feedback on this!

Cheapest way to go is a good used cylinder and pistons. Realize though, you should install new rings which are not cheap and OEM gaskets are vastly superior to aftermarket and they are not cheap either.

Looks like money

Gotta pay to play

It took both of us working together 8 hrs. or so to get a piston out of a rusted bore on The Wounded Z. We just resleeved that gug, as all the bores had rust damage to some extent & we already had a set of std. pistons & rings on the shelf.

Looks like that piston is pretty close to TDC, which might complicate things a little.

The thinnest possible lube/penetrant will help. We're partial to a 1/2 & 1/2 mix of acetone & ATF. Let it soak for a few weeks, renew daily. DO NOT use a torch for heating as described below; acetone is extremely volatile and explosively flammable.

We made a cylinder lifter based on an idea from an old Z1 service bulletin. The pic below should be self-explanatory.
EDIT: see post #791431 for more details on the cylinder lifter.
kzrider.com/forum/forum-index/11-project...ed-z?start=12#791431



Heat is your friend and enemy. Heat the cylinder for a long time with a heat gun or concentrated output from a small ceramic electric heater. There's a lot of mass there, so it takes lots of output and time to really get it hot. Cool the piston (ice cubes) just prior to each lift attempt is the working concept.

Once the piston has dropped in the cylinder some, there may come a point where you'll run out of stud. Pushing the cylinder down some will cause pistons 2 and 3 to rise. Slide wood strips under #'s 2 and 3 to prevent them from dropping as you continue to lift. We had to use a 3lb. machinist's hammer & wood block to drive the stuck piston down sometimes. Finally, enough of the piston pin was exposed under the liner that we could remove the circlip & press the wrist pin out with the piston still in the bore, allowing the jugs to be lifter free from the remaining 3 pistons. We had to use a press to get the piston the rest of the way out.

Good luck. Patience...

Good Ridin'
slmjim & Z1BEBE