Short answer : Don't try.
There were many fora on the internet before PG created HN and many others have sprung up since then.
The allure of HN is its mix of contributors, expert opinions and topics as well as the civility of the conversation(s).
A forum focussed narrowly on "hacking" would soon read like a monograph and quite likely die shortly thereafter.
Instead of trying to change the offering, embrace the experience.
What's inherently wrong with political talk other than it makes [you] feel bad?
Politics certainly impacts technology (and technology politics, see gerrymandering in the US). Technology serves no purpose other than to bring efficiency into our lives (be it for entertainment or productivity, or ... ), so what's wrong with discussing politics as it relates to technology?
Or, what's wrong with discussing political problems, with hope that we can "hack politics?"
Unfortunately, user feedback loses its powerful when a product is already "successful".