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How To Break Free A Stuck Piston?

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I am rebuilding a KT250. Among the spare parts the bike came with is a spare engine in which the piston is stuck. I believe the rings have rusted to the cylinder wall. Anyone have a good way to break this free?

Plus Gas, WD40, heatr and a very very big wooden mallet have ofetn helped me. The piston bore and rod need rebuilding so heat it up and beat sh&t out of it

Lee

I am rebuilding a KT250. Among the spare parts the bike came with is a spare engine in which the piston is stuck. I believe the rings have rusted to the cylinder wall. Anyone have a good way to break this free?

A good penetrating oil to soak the mess is good to start. I've unbolted the cylinder, raised it up as far as it will go (hopefully it is stuck in the middle of the stroke) and slid some wood under the base so I can use a block of wood and a mallet to whomp on the piston crown without damaging the sealing surface of the cylinder base. You may need to add more wood under the cylinder as the piston travels down (hopefully). Be sure the crank pin is not at the bottom of the stroke, otherwise the piston has no where to go.

Jon

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Success, sometimes a BIGGER hammer is the correct tool.

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