If the ridge is really bad, you will want to borrow or rent a tool called a ridge reamer.It fits down inside the cylinder and cleans the ridge from the bottom up to the top and allows easy removal of the pistons.(Be sure to use some pieces of snug fitting hose on the connecting rod bolts so you do not scratch the crank journal when you shove the piston out of the cylinder smile

There is enough good in the worst of us and enough bad in the best of us that it does not behoove any of us to criticize the rest of us.
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Be yourself. If you are ever lost, It will be much easier to find yourself if you know who you are!