G250V - unusual tuning problems

[Open Ocean Diver]

I used Scubapro OEM service kits, all OEM parts, but cannot get it to crack above .8 without diaphragm lever separation. Ugh

I haven’t replaced the spring yet, it has the original spring when I purchased the reg used.

Edit:
Replaced spring and without any adjustments now cracks at .9,

When yours cracked above one, assume your adjustment knob was all the way out?

 

[lexvil]

If you find a Slug in your regulator be sure to give it a good rinse before diving.

auto correct was especially interesting today.
No power here so super slow connection through my phone.

 

[aoumi]

I'd look at the orifice/knife edge under a loupe. I'll bet you'll see some irregularities. When you polish them out with some Micromesh, you'll be able to get your cracking effort with much less spring pressure. And without the lever drop.
Sad to say, that's why the G260 is such a significant improvement over the 250 ‐ lever height adjustment is separate from spring tension.

That's something I'll have to check, thanks for that. I'll hunt around the house for a suitable magnifying device (or go out and buy one) and take a closer look at that knife edge. It passed the fingernail test from memory, but a closer look is warranted.

 

[aoumi]

Just another thought in addition to ideas above, were the poppet & balance chambers tested to verify they are working properly?
Seal the low pressure seat orifice (I use tip of finger) and then install the balance chamber without spring on the poppet. After a light push down on the balance chamber, it should spring back after releasing.

Yes, after my first round of head scratching, I did this test. It sprang back fine so appears there is no there. I then tried swapping out another balance chamber from my S560 and tested, but the tuning result was the same.

 

[Open Ocean Diver]

When you turn in the orifice to just stop any leak how’s the lever height?

 

[aoumi]

Lever height is the main factor you need to consider with that adjustment (orifice) then put in a new seat and use your adjuster knob to stop the leaks, if any. If that doesn’t work you may want to change the poppet and see what happens, once you get them working sell them and buy a g260 or a D420, the 250 is a pretty simple animal and I can’t imagine anything sitting in sun could damage other than the seat.

I tried a couple of different seats (one from a new service kit), and a few different poppets. Some yielded slightly better results than others, and it was interesting to note the poppet wing design had ever so slightly changed between some of the older and newer s-wing poppets. Some of the poppets, the contact point where the lever arms contact, were straight up and down. Other newer ones were identical except the end of the plastic was off at a 45 deg angle. The straight were the originals. Pics below, original poppet at top, newer one from service kit at bottom.

What I haven't tried properly, is following your suggestion and setting the orifice just for lever height, and then adjusting in the adjustment knob to get the correct cracking effort. I kind of did a combination of using the orifice to get lever height somewhere near correct and trying to stop any leak, and then screwing in the adjustment knob. Bit I think from memory I had to screw the adjustment knob in a bit more than I thought should have been necessary. I'll retry just setting for lever height though.

 

[aoumi]

Did you use ScubaPro seats, or something else? If the seat head is not the same thickness, you will have problems.

I did get some new seats seperate from a kit, but my understanding is they are OEM seats.

 

[aoumi]

When you turn in the orifice to just stop any leak how’s the lever height?

Can't remember now, but I'll do this and report back...

 

[Rusty Shackleford]

@Buddahsummer should add his two cents on this. He has beaucoup G-250V experience.

 

[aoumi]

Whats the IP from 1st stage?

Can you post some pics of 2nd stage internals?

Pics below...