1st time overhauling my MK25 - could use some help, please

[divedrewsf]

Nope... G260 has a micro-adjust on the balance chamber side so you tune orifice to set lever height, and micro-adjust to set cracking effort...

hmm...okay, i don't recall this from the video i used to teach myself.

question, the G260 just have never breathed as well as my G250s. do you think this has to do with the one of these adjustments not being fine-tuned properly?

i was all excited when I got the mk25+g260 thinking it would be a step up from the mk11+g250 combo i had been diving for years. but i found the latter to breath better.

 

[divedrewsf]

update, yep...the G250 was the culprit. it was a 'newer' one I acquired over a year ago (more?) and I hadn't serviced it yet. even though the barrel looked spotless, there was so much grease/crud on the inside of the adjustment knob. jeez, it even had the old poppet in it!

anyway, overhaul fixed it and all is good.

(although i still think the G260 needs some fine-tuning to breath better...will look more into that)

 

[lexvil]

update, yep...the G250 was the culprit. it was a 'newer' one I acquired over a year ago (more?) and I hadn't serviced it yet. even though the barrel looked spotless, there was so much grease/crud on the inside of the adjustment knob. jeez, it even had the old poppet in it!

anyway, overhaul fixed it and all is good.

(although i still think the G260 needs some fine-tuning to breath better...will look more into that)

The G260 is very easy to tune, look under the black “button“ on the adjuster knob for the micro adjustments.

 

[El Diablo]

hi all....thank you for your comments!

good news/bad news. good news is there are NO leaks from the 1st stage....that appears all tight. But, the bad news is that I have a G250 as my octo and that *was* leaking. and when I try to adjust the cracking point on it, I just can't get it to work at all now. I did not overhaul this when I did the MK25 + G260. Maybe that's the issue?

but....I took a R295 from another rig and it took care of the issue. IP holding firm at 130 and no leaks when the tank is shut off!

so, maybe this combo - MK25 + G260 - just doesn't 'like' the G250 as the octo? I'll tinker more and see (hook up this G250 to the other rig I took the R295 from)

again, thank you!

Sorry to sound a little cliché BUT if you are going to dive with that combo, perhaps you should take it to a professional to avoid any unnecessary UW scares?

I mean, that combo should require service every 2 years so not a huge cost to factor-in especially if you include the peace of mind...

 

[divedrewsf]

The G260 is very easy to tune, look under the black “button“ on the adjuster knob for the micro adjustments.

Fantastic....I can tell the difference. Excited to dive this soon.

Thanks so much...you're the man!

 

[divedrewsf]

Dived it this weekend and it worked great...except for a big hole that suddenly appeared in my mouthpiece causing me to suck in a bunch of water, lol. Thanks for all the help.

But, I do have one final question...what do the plastic bushings in the piston assembly do? As I said earlier, there were TWO in there from the factory. I only replaced one. And I notice that I have to crank down the IP screw all the way to get me to 130psi. If I add the other bushing, will that help me tune the IP down closer to 125 (should I ever want to)?

 

[rhwestfall]

Yes, those are IP shims.

 

[halocline]

Dived it this weekend and it worked great...except for a big hole that suddenly appeared in my mouthpiece causing me to suck in a bunch of water, lol. Thanks for all the help.

But, I do have one final question...what do the plastic bushings in the piston assembly do? As I said earlier, there were TWO in there from the factory. I only replaced one. And I notice that I have to crank down the IP screw all the way to get me to 130psi. If I add the other bushing, will that help me tune the IP down closer to 125 (should I ever want to)?

Two questions, first are you serious that a 'big hole suddenly appeared' in your mouthpiece during a dive? That's not a normal thing at all. If you're not just joking about it, then please inspect your mouthpiece before putting your reg back together after service. If you didn't remove the mouthpiece when servicing the 2nd stage, then you didn't do a good thorough job. The fact that you didn't know or bother to leak check it after assembly is another issue.

Second, about the bushings , YES it is important to replace both bushings, as well as as any other parts that came out of the 1st stage. Didn't you bother to look at a schematic, or at the very least take some quick photos of what came out of your MK25? Those bushings surround the HP piston o-ring and prevent extrusion, if they are the ones I assume you're talking about. They are very important. You should immediately dismantle your MK25, consult a schematic, and make sure that ALL the parts on that schematic are installed in the right place.

Usually I try to be pretty encouraging with self servicing your own regulator. It's not rocket science, it's not even particularly complicated. But you have to be careful and honest about your abilities and attitude about doing the best job you can. Sorry for the rant.

 

[rhwestfall]

@halocline - he is using the wrong terminology, and meant the shims used for IP, not the piston stem bushing....

Yes, It still follows that "parts out = parts in" should be practiced....

Mouthpiece? Yeah, spot on!

 

[halocline]

@halocline - he is using the wrong terminology, and meant the shims used for IP, not the piston stem bushing....

That makes more sense.