Polarstar Kythera SA Replacement Disconnector

The disconnector is the part of your HPA engine that enforces semi-auto discipline. Every cycle it physically interrupts the trigger circuit, and it doesn't re-engage until the bolt has completed its full travel. That mechanical timing is what makes each pull fire exactly one shot, so when it wears or fails, the symptom is immediate: a second pull that doesn't fire, a misfire right after a normal shot, or a trigger that simply won't reset.

This is the replacement disconnector for all versions of the Polarstar Kythera HPA engine. It's machined from steel, which is the standard material for Kythera internals — harder than polymer alternatives and built to handle the same cycle counts as the rest of the engine. It fits every Kythera variant, so you don't need to cross-reference your sub-model.

When you need one. Disconnectors are wear items on high-round-count engines. If your Kythera has started dropping shots on semi-auto — firing normally one pull, then nothing the next, then normal again — the disconnector timing has likely shifted or the contact surface has worn. This part swaps directly into place and restores consistent semi-auto behavior.

What you need to know. This is a single disconnector and nothing else. You'll need basic engine tools to disassemble your Kythera and access the trigger group. The Kythera's internals are compact, so take your time with reassembly — forcing parts into place is how you bend a disconnector tab or scratch a housing surface. If you're doing this for the first time, watch the Polarstar service videos before you start.

Ships with 30-day return and warranty from Polarstar.