New to me MK10+/G250 R109/108

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dstalsby5

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Purchased a MK10+/G250 and MK5 R109/108 set up. I thought the Mk5 was a Mk10 😒.Going to get them serviced in near future.
Been doing some reading on upgrading the 109. Seems like there is more then one way to go about it.
Correct me if I am wrong but I’ll “aka” the service tech will need a G250 kit, new spring, S-wing poppet or euro poppet and balance chamber.

Anyone look for a Mk5.. I’m looking to pick up a Mk10 for my 109
 

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James79

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On the 109, the 2 main routes people take is duro poppet or balanced adjustable. I don't bother with balanced adjustable... Just make sure it has the duro poppet so the seat is cheap and easy. When properly tuned few can tell the difference between a 109 and a BA (presuming it is on a balanced 1st stage). If your 108 is a 108HP (adjustable orifice) it's a great find. Properly tuned they are good breathing bullet proof seconds.
Regarding the MK5, they are functionally the same as a MK10, unless you want to go the sealed route (presuming the particular MK10 has the groove for a SPEC boot). My 16 y.o. dives a MK5 (I'm more of a Conshelf guy for single hose 1sts). I would just dive the MK5... But if you truly want a MK10, @Couv can probably hook you up. If not, I probably have one on my "to be rebuilt" shelf.

Respectfully,

James
 
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dstalsby5

dstalsby5

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I do not know a whole lot on the 109. Just trying to get an idea on what I need to know to make sure they are set up right. I am sure the tech will know… but you never know. I am not sure if the 108 is hp. I have a couple of MK2 that are already serviced that I am going to use if I can not get a Mk10. Just don’t have a need for the 5
 

Kupu

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As mentioned by James, the 109 can be configured as balanced (s-wing poppet) or unbalanced (duro poppet). Either way, the internal parts currently installed will determine if upgrades need to be done. The attached schematic shows both configurations, with older style poppets. If the 109 was serviced in the past 15-20 years, it may already have current version poppet and related parts installed.

To upgrade unbalanced 109 to balanced adjustable. Remove unbalanced poppet, spring, and pad. Replace these parts with new s-wing poppet, spring, and balance chamber. Plus standard servicing procedures.

The G250 may need s-wing poppet installed, if it has an older style balanced poppet. A new spring and/or balance chamber sometimes will help improve performance, but not always needed.
 

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dstalsby5

dstalsby5

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I’m not too worried about the 250 due to the fact my wife has already claimed it is hers.🤣🤣
So I want that 109 to be a “smooth operator” It is the 1965 Lincoln Continental of regulators IMO.
We live a couple hrs from the Gulf of Mexico and with the type of diving, you can not tell much of a difference in a balance or unbalanced reg. BUT since I am bringing it in, I’m going the balance route.
 

James79

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I’m not too worried about the 250 due to the fact my wife has already claimed it is hers.🤣🤣
So I want that 109 to be a “smooth operator” It is the 1965 Lincoln Continental of regulators IMO.
We live a couple hrs from the Gulf of Mexico and with the type of diving, you can not tell much of a difference in a balance or unbalanced reg. BUT since I am bringing it in, I’m going the balance route.
Depending on your shop, some won't work on vintage regs. If yours will, that is great and make sure you develop a good relationship with them. If not, there are reg techs on this board that will do mail in service. Or, if you are mechanically inclined, you can go the DIY route... I did about 5 years ago and haven't looked back. A wiser man than me pointed out that servicing regs isn't hard, it's just precise. And those regs don't require much in the way of special tools.

Just food for thought,

James
 
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dstalsby5

dstalsby5

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Depending on your shop, some won't work on vintage regs. If yours will, that is great and make sure you develop a good relationship with them. If not, there are reg techs on this board that will do mail in service. Or, if you are mechanically inclined, you can go the DIY route... I did about 5 years ago and haven't looked back. A wiser man than me pointed out that servicing regs isn't hard, it's just precise. And those regs don't require much in the way of special tools.
Just food for thought,

James
Yeah when I called about the 109 he had to call me back to go check if he had one. He had ONE, that is one reason I was asking in case I have to procure the parts myself. I am wanting to start getting into doing the service work myself, one of the appeals about the 109 but trying to refrain from going down another rabbit hole.
 
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dstalsby5

dstalsby5

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As mentioned by James, the 109 can be configured as balanced (s-wing poppet) or unbalanced (duro poppet). Either way, the internal parts currently installed will determine if upgrades need to be done. The attached schematic shows both configurations, with older style poppets. If the 109 was serviced in the past 15-20 years, it may already have current version poppet and related parts installed.

To upgrade unbalanced 109 to balanced adjustable. Remove unbalanced poppet, spring, and pad. Replace these parts with new s-wing poppet, spring, and balance chamber. Plus standard servicing procedures.

The G250 may need s-wing poppet installed, if it has an older style balanced poppet. A new spring and/or balance chamber sometimes will help improve performance, but not always needed.
Thanks for the info. That was want I was looking to know
 

James79

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If you're asking why some shops won't service old regs, it's equal parts marketing, fear of litigation, and ignorance. The marketing aspect is "those old things can't be serviced anymore, here spend $$$ on these new ones". The fear of litigation is a belief that they are at risk if they use anything other than a factory supplied "Service Kit".... even though a duro 90 -10 O-ring is the same whether it was bought in bulk or as part of a kit. The ignorance is that many techs aren't really techs... they are parts swappers. If they don't really understand the gear and just do what book says so because book says so, they won't ever look beyond a factory parts kit or availability of new parts from the manufacturer.
If you're asking who will do servicing on this board, I hesitate to throw names out without checking with them first. If your shop won't work with you, just put up a thread here and I suspect you'll get a number of people willing.
If you're thinking of DIY, for those specific regs I'd look here: https://www.youtube.com/@Vintagedoublehose1964
Bryan did a number of videos going through them step by step (the MK5 and 10 are similar enough that the MK5 video covers it.

Respectfully,

James
 

halocline

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I'm not sure why you are forsaking the MK5. I personally prefer them to MK10s, and yours is one of the later, more desirable MK5s with 5 LP ports and a heavy yoke. I would definitely keep that and service it. You may find that the MK10+ has it's problems. It uses a blunt-edge piston and the MK20-25 seat. The combination was designed to increased airflow but IME they tend to have problems with IP creep. I can't get any of my MK5s to creep even if dive them for years without rebuilding.

Regarding the 2nd stages, you've already received excellent advice, personally I convert my 109s to balanced. Sometimes the older levers work well with the s-wing poppet, sometimes not and it seems to be a bit of a crapshoot in terms of performance. The general issue is that some, not all, of the older levers result in a bit more lever height than the newer 'curly feet' ones. This requires you to tighten the orifice a little more to drop the lever, and the cracking effort increases. I also have found that there is some inconsistency in the springs. I always replace them when I'm rebuilding/converting a 109 or 156 (which is the 'balanced/adjustable' younger brother of the 109). I have spent many pleasant hours fiddling with various levers and spring combinations to get the best performance out these older, classic metal 2nd stages. When you get it right, they are wonderful to dive with, better IMO than the G250. In fact, I've come to the point where I'm only using B/As and 109s in my cave diving, so I have several. (Thanks to a few folks on this forum!) I also use a pair of MK5s in my cave set up and have semi-retired my sealed MK10s. They just don't last as long between rebuilds IME as the MK5.

Bringing an end to this long rambling post, I feel that you have the ideal combination right there; a late model MK5 with a 109. So let your wife use the G250 and let someone else deal with the creepy MK10+.
 
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