Author Topic: Fork air valve size  (Read 647 times)

Offline wymple

  • Guzzi Hero
  • *****
  • Posts: 699
  • Location: SE Iowa
Fork air valve size
« on: April 25, 2016, 11:03:50 AM »
So, on my 1984 Cal II I have air valves for the cartridges. I would like to connect the two into a single fill point to maintain balance between them. Does anybody know what that oddball thread is on the valve? I'm trying to locate some push valves that might screw in there so I can run both lines to a T, and maybe add a small tank to the equation as they hold so little air it's difficult to set the pressures just so.
No trees were harmed by the conveyance of this message, but a lot of electrons were seriously disturbed.

Offline rodekyll

  • Guzzi Hero
  • *****
  • Posts: 21235
  • Not my real name
Re: Fork air valve size
« Reply #1 on: April 25, 2016, 02:13:38 PM »
They are probably not service valves.  They are probably there from the factory fill, and only because they can't be removed without losing the gas.  Unless someone comes by with a good argument for doing what you propose, my advice is to not mess with them -- that's the advice I've been given for the same question.


Online Moto

  • Guzzi Hero
  • *****
  • *
  • *
  • *
  • Posts: 3098
  • Pazzi per la Moto Guzzi!
  • Location: Madison, WI
Re: Fork air valve size
« Reply #2 on: April 25, 2016, 02:53:25 PM »
So, on my 1984 Cal II I have air valves for the cartridges. I would like to connect the two into a single fill point to maintain balance between them. Does anybody know what that oddball thread is on the valve? I'm trying to locate some push valves that might screw in there so I can run both lines to a T, and maybe add a small tank to the equation as they hold so little air it's difficult to set the pressures just so.

In addition to RK's point, if you added volume to the two cartridges' air chambers either by connecting them with a tee, or by adding a small tank, you'd change the progressiveness of the pressure. That is, they would no longer be as progressive. You've considered this too?
1976 850-T3
2007 GRiSO 1100
2017 Italjet/SSR Buccaneer 250i

Online Kiwi_Roy

  • Guzzi Hero
  • *****
  • *
  • Posts: 7117
Re: Fork air valve size
« Reply #3 on: April 25, 2016, 03:57:22 PM »
On mine they were connected together with just one valve.
At least they were until the interconnect tube got britle
The manual says
Front 3 kg/sqcm +/- 1  28.4 to 42.7 psi
Rear 4 kg/sqcm +/- 1   42.7 to 71 psi

I don't have valves on the rear
72 Eldorado
07 Griso 1100
17 V7iii Special

Moto Guzzi - making electricians out of riders since 1921

Offline charlie b

  • Guzzi Hero
  • *****
  • *
  • Posts: 6944
Re: Fork air valve size
« Reply #4 on: April 25, 2016, 06:46:08 PM »
Are they the original cartridges with an air bladder in them or are they FAC's or did that bike have something different? 

My FAC's had air valves in the top but all they did was pressurize the inside of the fork, which would leak past the (new) seals.  I don't put any air pressure in them and they work fine.

If original with the bladder, I heard someplace that the purpose of the air pressure was to change the spring pressure/orifice size on the shock valve, not to change the preload.  I may be completely wrong and someone who knows better should answer.
1984 850 T5 (sold)
2009 Dodge Cummins 2500

Offline wymple

  • Guzzi Hero
  • *****
  • Posts: 699
  • Location: SE Iowa
Re: Fork air valve size
« Reply #5 on: April 25, 2016, 07:26:21 PM »
I have cartridges, and they hold air just fine. But there is only a very small amount of air involved and getting both sides the same is a touchy proposition at best. It rides much better if I have about 20 lbs in each one, I'm going to try up to 30 lbs & see what gives.  That also raises the front end height about an inch. Some claim the air makes no real difference, but I find it very noticeable, especially on washboard surfaces and RR tracks.I am connecting the two so that they will automatically balance each other regardless of the actual pressure involved. Today I found barbed hose fittings that thread right onto the valve stems. A local bicycle shop knew what I needed as they had recently dug some up for a project. I can run them to a T and be good to go, but I will probably put a smallish tank inline as well.
No trees were harmed by the conveyance of this message, but a lot of electrons were seriously disturbed.

***Wildguzzi Official Logo High Quality 5 Color Window Decals Back In Stock***
Shipping in USA Only. Awesome quality. Back by popular demand. All proceeds go back into the forum.
http://www.wildguzzi.com/Products/products.htm
Advertise Here
 

***Wildguzzi Official Logo High Quality 5 Color Window Decals Back In Stock***
Shipping in USA Only. Awesome quality. Back by popular demand. All proceeds go back into the forum.
http://www.wildguzzi.com/Products/products.htm
Advertise Here