Replacing the chain as maintenance? Absolutely not. If your chain is rattling or something it's the tensioners, they do go bad occasionally, I would replace the chains and guides and sprockets at the same time as tensioners, but by no means would I replace any of it without having a problem. It's not like a belt, the chains don't stretch over time. The tensioners take up enough distance to make up for the tiny bit of stretch they get over time.

 

Allows the piston to travel further up and get more compression.