Topic: '72 CB 500 Piston Rings Rusted To Cylinders

[ktp1598]

I had a similar problem with my F2. I used a hammer and a block of wood. That didn't help. Then I noticed a little bit of movement at the cylinder base. Careful prying under the cylinders from both sides finally loosened all pistons. I know this isn't the best way as it can scratch or mar the machined surfaces, but it was the only way I could get them loose. I even tried pb blast, had that in there for 2 months. Anyway, the gasket surfaces look ok, as does the cylinders (with a hone). Good luck.

[tomkimberly]

I would say your only choices are to soak, tap the tops of the pistons with a block of wood, and repeat until you can get them to move so you can remove the cylinders. It could take a day, a week, or a few months.

FWIW, have you considered using vinegar, it is a weak acid and can dissolve rust.

Tom