Reg Not Free Flowing??

[Andrew Dawson]

Greetings!

Little back story:

I have two nearly identical reg sets: MK25/S600s.

One S600 is a Gen 1 [1999 to 2003] with a plastic air barrel, the other is a Gen 2 [2004 to 2006] with a 4th Gen metal air barrel conversion. Both have new metal orifices from Vintage Double Hose. Both were recently fully serviced [that is when I did the metal air barrel conversion].
The Gen 2 is on a 7' hose, the Gen 1 is on a 30" hose.

The Gen 2 with the metal air barrel did not seem to breathe as nice as the Gen 1 with the plastic air barrel on a recent dive. I decided to retune the regs to see if one was "off".

I could not get the metal air barrel reg to free flow...with the VIVA set to "Dive" and the knob turned all the way out [both regs were tuned with the knob halfway in/out...where...with knob all the way out would produce a little bit of a "hiss" or slight trickle of air].

Both of the MK25 have IP set a bit low for less chance of icing up...at 125psi. The Gen 1 S600 with the plastic air barrel behaves as expected...press the purge button with the VIVA set to predive, no free flow. Press the purge button with VIVA set to "Dive" and it free flows.

Both regs have the VIVA in the max config with the crescent cut out side towards the purge button.

Any idea what this could be as to why the Gen 2 is not free flowing? Is that how all the Gen 4 [latest] S600s perform? Is it possible the micro adjuster is not set correctly?

Any tips would be greatly appreciated!!

 

[halocline]

Is the cracking effort the same on both 2nd stages?

 

[Andrew Dawson]

Well, several mistakes on my part during this last round of annual service and tuning.

I never got out the magnehelic gauge as I figured I could just do the "normal" tuning procedure and the cracking effort was what it was.

In this case...I had a bit of trouble understanding the orifice vs micro adjust tuning differences.

This time, I set the micro at 1/2 out...set the orifice to just seal then plus 15 degrees...then pulled back on the micro adjust.

It ended up with the micro adjust all the way out.

Now, it definitely breathes better...I believe it is about 0.8" to 1" is the cracking effort...the mag gauges are not the easiest to read when sucking with your mouth vs a machine, IMHO.

The issue this time with the reg not free flowing...after a better tune where it will easily free flow without the mouthpiece...is that the mouthpiece has a smaller opening on the mouth side than the reg case opening where the mouthpiece attaches.

So, a bit of careful hacking with a razor opened it up...and it free flows easily with the mouthpiece on now