How does Kythera works ? + Dwell/air volume adjustment #kythera #polarstar #hpa

Hello fellow airsofters.

I have cracked down how does the kythera operates and how to change the dwell/air usage of the engine as par of my quest to solve the PSI lag issue with the engine on fast semi.

I hope it will help anyone who would need the info.

Dump chamber spacers can be found at

2.5mm one did not fit over the spool (for older kytheras where the spool is "circle" it might fit)

[xavphone]

Hi. Thank you SO MUCH for this video, and your answers to the comments.
Please, I need some help. I bought a second hand Kythera, and a second hand Wraith-X. They are in great conditions, and I am trying to install them in a cyma Colt Keymod CQRB, with a 6.01 x 375mm PDI barrel, with prowin hop up, MR HOP maple leaf bucking.

My problem is : I have hight inconsistency. Overall, my joules are +/- 0.1 joules with consistent rate of fire. But here is the thing... My first shot will be 1.72 joules. I wait three seconds, 1.7 joules again. But if I wait only one second, it drops to 1.6, and if i do like 2 or 3 rps, it drops to 1.4 joules.

1- Is this only an alignement problem, or is my wraith-x involved in you opinion ? It is only mechanical, and no parts looks damaged, on both the kythera and the wraith X.

2- Also, I lubed everything with Abbey Silicone gun grease, is it wrong ? Do you recommand this type of build for milsim use ?

3- Would you avise me to sell my kythera, and buy a F2, due to the reduces autonomy I have ?

4- Should I also buy a higer quality external replica ? If so, what brands would you recommand for a good alignement ?

Hope you'll see this comment. Thank you so much.

[r.in.shibuya]

Thanks for sharing this mod looking forward to testing it out. What are your methods on testing over all air seal (no barrel, engine only)? I am assuming air can leak out of the nozzle... But are there any other locations where tha air can leak? Given you did a full o-ring repalcement how coud you test that there is no leak?

[shanehosto]

I have my in a v3 gearbox in an lct started out great then slowly over time with no heavy use would discharge without shoot and i would have to manually charge it. And now it wheezes and wont charge the system eventually it will charge and shoot but it's spotty at times. And local airsoft techs seem to have no clue and say that it's fixed when it isn't.

[Chretze]

Hi Tatko!
You seem like the most knowledgeable person on YT regarding the Kythera, can I bother you with a few questions about it?

Would you say the Kythera is more consistent in J output compared to a high end AEG gearbox? I read a lot of claims online and some of my friends swear by HPA systems in general for this reason, but because they literally call themselves "HPA fanatics" I assume there is some bias in their judgement ;)

Follow-up question: The airsoft fields where I play often have vastly different rules regarding max allowed bb weight and fps, so HPA is appealing to me because it allows me to adjust fps on the go easier than any spring change system. The idea is to build a DMR-type rifle around the Kythera intending to shoot bbs ranging from 0.3g up to 0.45g with a relatively long barrel (about 460mm), I imagine it is necessary to adjust dwell to accommodate for the change in bb weight (which is the main reason I searched for your video), is this true? If yes, would this dwell adjustment be easier on an electric HPA system?


Last question: I'm intending to use a UGS stock so the limiting factor for me will be the small air volume in the 0.2l tanks. Would you say the Kythera is more or less efficient compared to electric HPA systems, or is there no big difference?
And is there a noticeable decline in FPS as the pressure in the main tank drops while shooting?

Sorry to barrage you with all these questions at once, but so far I haven't found any solid answers to any of these online.

[danielfink]

So, just a small question.

Does the Kythera then handle 4 RPS just fine or should I try to stay at around 2-3 RPS? My "natural" triggering rythm is around around 4 RPS, do you think the Kythera will keep up?

Also would a shorter barrel help? Since a shorter barrel won't need as much air as a long one or am I misunderstanding the dump chamber design?

Otherwise, excellent video!

[squidmonkeystudios]

Any chance you can explain more about the Dump Chamber Spacers in you video description? Do these help with the slower chamber refresh rate?

[avengerking]

I have one as of two weeks ago and it already leaks out the nozzle and all I did was install it in a gearbox.

[JoJoker]

I have a issue with my kythera: every 3 shot or so, the nozzle stays in the back position and I can not shot. Than I had to disconnect the air supply, the nozzle goes forward, pull the trigger, I can here the click of the trigger and after i connected the air supply again, it does shot again.
Can you help me with an advise?
Thanks in advance

[tankprohp]

Quick random question just bought a blemished kythera and every time I connect air it leaks ever so slightly but stops when I lightly press the sear before it goes off any tips brand new to HPA

[mayhem]

Hi tatko
i have a question.
Whats the diffrent about the hard and soft Spring from the kythera

[silviosilveri]

hi there we are having problems with a huge inconsistency in the acuracy of the shoots, it looks very randon and there is not a fps inconsistency help please

[lyleeewang]

Is it possible to reach 8joules with kythera?

[RedNeckActual]

Do we have any data on the air volume a kythera pushes into the barrel when it is in its standard configuration?

[GregoirEAzer]

I've a kythera too, when my PSI are at 120PSI, the first shot work at 120PSI, then the others are between 80-100PSI... Around 110 to 130 PSI is the minimum that I've to put into the kythera and I don't like that, because i'm around 370FPS at 120PSI and around 320FPS after several shots :/

[petercarlson]

Would adding a spacer help fix air volume issues with shorter barrels? Im running a 260mm barrel and im getting crazy fps inconsistencies

[TankAirsoft]

Uhm Tatko may you please summarize how it works (I think it will help me understand the video)

[lyleeewang]

what if I want the opposite.. I want to increase my joules.. how do I do that?

[arwynhockridge]

what nozzle do i need for the mk12 mod 1double bell

[BrandonBrownOctaneOverdrive]

I could not focus at all with that banger playing in the background.

[chango]

Hello, first of all, sorry for the language, I don't speak English well.
my kythera has a problem that launches two BBs when firing
I did a thousand tests and I can't solve it
I have recorded a video in slow motion and it is seen that the nozzle bounces when activated

Any idea how to solve the problem? I don't know many people who know so much about this system.
thanks a lot