For sale is a used Polarstar kythera. Perfect engine for those getting into HPA as it's purely mechanical no need to set dwell or fcu settings etc.

In theory (gearbox compatibility dependent) this setup is a drop in HPA setup. 

With it being mechanical this is semi only which lends itself to being in a dmr build. 

It has had the .019 metering screw put in (nightmare to get hold of).

The trigger system has been set up for reduced trigger, works really well with the included Maxx trigger.

I've put it into a spare VFC gearbox, this is the gearbox Polarstar are designed around.

Also included is the amped grip line which has a nice thick weave. Annoyingly polarstar don't ship with ready to go lines.

I haven't done it before taking the pics but I will also chop down the spring guide and set it into the gearbox. 

In its current setup the charging cable will run into the buffer tube. Pair that with paracord that I can include, and it be hidden away by the stock. The cable got nicked with one of the threads splintering, cable is absolutely secure but the bloody wire is sharp! I've covered it with electrical tape to stop it catching skin when installing. 

The only thing I would change is the gearbox screws. These have come out of spares box. Might be worth whoever buys it spending £3 from ak2m4 and getting some new ones.

The engine itself is retailing for £320-£330. That doesn't include the £25 grip line. Trigger is about £25. The metering screw with postage is £20 (p*ss take) and the gearbox will set you back £20-30. 

All in all its about £450 in parts of you were to buy new. Plus you don't have to mess around with setting the screws for the best trigger pull!

For reference I had it paired with a 285mm PDI barrel, maxx m4e hop unit and a maple leaf macaron (old style not super). It was giving a FPS deviation of 1-2fps. I've recently cleaned it all out reapplied tech salve to the o rings so it's ready to go.