Question Cyklon cross pairing? (and diy questions)

[Mobulai]

So, a while back I picked up a few cyklon 300 sets (some had the 1xxx 1st stages, some the 2305 with one even having a sealing cup, one had a 29xx)
They were pretty nasty and I parked them a while while dealing with a mountain of g250s and other „easier“ to deal with regs

I finally picked one up today and decided to give it a go
The 1st stage (2305) is partially disassembled (gotta get me a 28mm flat crescent wrench), so it’s kinda on hold, but also the metric threads need adapters for new hoses so… not sure if I wanna use these

I decided to see if I can just get the simple 2nd open, cleaned and mess around with it

After some fiddling and frustrating attempts, I got it (mostly) open (couldn’t open the „cover“, bit the inhale diaphragm breathed/sealed alright); cleaned, flipped the seat (for now), and closed it up (after some more frustration to engage the lever)

… (i am typing this while taking a break from torturing my very 1st cyklon, I got no clue what I’m doing here; eg. I’m checking it on an mk17 I know it’s a no-no, but didn’t get to even open that 300 1st stage yet. send help)

Ideally I wanna pair them with a different 1st stage (maybe an mk10), my (probably faulty) logic here is:
Cyklons have heavy springs that make them run at 160psi IP
If they get a lower IP it’s not that risky, I just gotta back away the orifice
Backed up orifice means less spring compression, so shallower seat imprint: chances tuning holds is longer

Now.. the question:
What am I missing? Is my logic sound or flawed?
Any advice/tips/warnings?
Maybe.. anyone tried a weaker spring?

Also, what disadvantage I’m creating by doing something like that?

Any generic tips for dealing with Poseidon regs are welcome as well, I have slowly started a small collection including a couple of Jetstreams and trying to get an Xstrea/mk3 aswell (keep getting outbid)

Thanks y’all

 

[rsingler]

The mechanical advantage of the Cyklon linkage is lower than a standard downstream. The "knife edge" of the orifice is a very flat cone. These combine to require the high IP's needed for smooth operation. But 160psi is attainable by most first stage regs pretty easily, though it maybe doesn't include the Mk10.
Running the orifice back for lighter spring pressure at a lower IP will create a very skittish seal with that hard orange LP seat. You could try using a softer hand-punched EPDM disc instead, but at that point, friction in the all- metal mechanism begins to have an effect.
In short, I wouldn't recommend tuning to a lower IP with the Cyklon. A great reg, with all position ease of breathing. But it really needs a good head of pressure.
Here's the cracking effort change of my Cyklon metal as IP drops (without changing spring pressure, obviously). You could improve on this by retuning, with decreasing reliability of seal as IP falls.
160psi - 1.0"
150 - 1.2"
140 - 1.4"
130 - 1.8"
120 - 1.9"
110 - 2.3"
100 - 2.5"

 

[Mobulai]

150 - 1.2"
140 - 1.4"
130 - 1.8"

That’s a dramatic jump..
I’m starting to see why an unbalanced diaphragm pairs with the cyklons best

I’ll dry test different combos them for the megnehilic, Ill try punching some seats and maybe also stick to the mk17 (even tho I have an mk10 that’s perfect for that experiment, shorter restored piston so IP is 145psi @100bar with no shims)

Also gotta source service kit/oem seat

 

[Bigbella]

Since the OP had also mentioned the Jetstream, I once had a set of cobbled-together regulators, which I had used out of necessity, which consisted of both Jetstream and Cyklon second stages, on a 2950 first stage; and which was surprisingly manageable.

Back then, the Diveair / Cyklon 5000 had been set to 10-10.5 bar; so too, was the Jetstream / Odin at the time. The Oceanair / Thor, in that older manual, was set even higher than later Cyklon models, to 12-12.5 bar.

The Cyklon 300 was originally set to a maximum of 13 bar!

 

[Mobulai]

No plans to pair 2 secondary stages on the same 1st on my side (for simplicitys sake) -- but 181PSI/13bar is still far too much than I could trust
I will continue with the exoeriment for experimentation sake; but it looks more and more futile

 

[Bigbella]

No plans to pair 2 secondary stages on the same 1st on my side (for simplicitys sake) -- but 181PSI/13bar is still far too much than I could trust.

No, I had never used any gear set to 13 bar; wouldn't really suggest that -- and, anyway, that's far too close for comfort with the old OPV hose limits of about 14 bar. That was just from an old manual by way of illustration -- since Poseidon futzed with, raised or lowered IPs over sixty-seven years, with the Cyklon 5000 having been upped from its original 10-10.5 to 12-12.5 bar in an odd 1987 typed addendum to the manual, of all things.

The current setting for the latest model in the line, the Cyklon X ( the same sixty-plus year old second, paired with an Xstream first stage), is 11.5 bar . . .

 

[IslandKraut]

I read above that you have multiple sets and at least one 29xx first stage. Since that one has the current 3/8 & 7/16 threads, it would be perfect for the second stages. Should be piece of cake to restore one of those, or if you don't want DIY - @rsingler can easily help.
Yes, I am opinionated, but I wouldn't pair a nuclear weapons rated Cyklon with a MK10 (which, for avoidance of doubt and complaints is otherwise a fine reg, of course).

 

[Mobulai]

I’m not saying that the cyklon 1st stages aren’t fine themselves, I keep hearing how awesome they are; but the lack of turret kinda annoys me as I mostly dive sidemount (and my lack of familiarity with their internals -yet)

I have a big cache of SP 1sts that I’m much more comfortable with servicing thx to @rsingler (esp mk10s, the lightest/smallest with turret) and I’d love to pair some of them with the cyklon 2nds for stage/deco bottles and such uses
probably the high o2 ones will be mk10+ if I go that route (as I can find nitrox HP seat for them opposed to mk10)

this thread is mainly an exercise in „what can I get away with vs not“, I started by testing the cyklon on an mk17 since it was the nearest functional 1st; I still didn’t open /restore any of the Poseidon 1sts I have (since I don’t have the right wrenches nor service kits yet).. and that got me thinking

So I decided to idiot proof my plans and ask the experts

DIY (and long surface intervals) is how I got to this state of experimenting

 

[rsingler]

I've been chatting with Poseidon's worldwide head of service. He mentioned caving with his Cyklons and running a lower IP.
I'll ask him what he uses and get back to you.
It may be that it'll tolerate lower than I thought.

 

[Bigbella]

I run a couple of my 300s at 10, maybe 10.5 bar, and they run quite well -- a tiny 44 psi departure, heh, heh, from that original 13.

Curious to see how low they'll go . . .