Author Topic: Unbalancing the JSA SS valve and using it regulated.  (Read 103 times)

Motorhead

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Unbalancing the JSA SS valve and using it regulated.
« on: November 30, 2018, 01:19:41 PM »
Disclaimer .... This is Not an approved or discussed modification with anyone at JSA.

This simple modification is a BYPASS of the valves Balancing feature having it operate as a conventional valve with a Cobra chamber.   Reason for is I run REGULATED on all my PCP's and the SS valve in stock form GREAT as it is unregulated simply was not satisfactory to my requirements while trying to run it regulated  :P.  So to not have this excellent valve sitting unused went about doing the simple modification of manufacturing a new poppet / stem that did away with the balance function.   Now the SS valve is ( Not to drop names .. but have too ) is now very similar to a WAR Cobra valve.
* Returning the valve to Balanced operation is a simple as a poppet / stem swap. use the supplied spring & required jet size.

Picture #1
Shows the "Balanced" poppet/stem with vent hole between stem at throat and secondary step in poppet head. ( Top of image )
In the middle ( Ref only ) is a WAR valve poppet from a pre-cobra valve.
Bottom is my custom poppet from PEEK with a poly o-ring to seal within the cobra chamber tube.

Picture #2
My PEEK poppet as it sits within the Cobra tube.
* Did taper the end of tube slightly to reduce any turbulence.

Picture #3
The intake side of the SS valve where I used a countersink in a hand drill and placed small flairs on each hole to reduce intake turbulence & smooth flow.


How does it work ?  .... Excellent making equal power to the WAR Cobra valve it replaced.  ;D ;D

NO .. Am not going to sell these poppets but only sharing what to do in bypassing a design feature & still use the valve at near full power potential.



Scott


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Alan

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Re: Unbalancing the JSA SS valve and using it regulated.
« Reply #1 on: November 30, 2018, 01:27:35 PM »
The only word I can think of—fabulous!
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Alan

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steveoh

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Re: Unbalancing the JSA SS valve and using it regulated.
« Reply #2 on: November 30, 2018, 02:08:13 PM »
Mighty interesting using a carburetor jet for an airgun valve. Was this a Travis invention or do other valve makers use this?

You do amazing work.
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Motorhead

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Re: Unbalancing the JSA SS valve and using it regulated.
« Reply #3 on: November 30, 2018, 02:32:22 PM »
It was a joint R&D venture in figuring out the Cobra chamber part of these valves and "Cobra Tech" in general ... Travis was the brain child for sure ! and the use of a screw in carb jet we came up with while talking one evening about how to calibrate air bleed in/out of the chamber.
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steveoh

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Re: Unbalancing the JSA SS valve and using it regulated.
« Reply #4 on: November 30, 2018, 02:37:02 PM »
It was a joint R&D venture in figuring out the Cobra chamber part of these valves and "Cobra Tech" in general ... Travis was the brain child for sure ! and the use of a screw in carb jet we came up with while talking one evening about how to calibrate air bleed in/out of the chamber.

I used to own an MuZ motorcycle with a 660cc four stroke single. It had a giant Mikuni carb on it, and it was super finicky about the right main jet. I had a box of those things for when I went to the mountains for fun. Now where did I put those? Hmmmmm.
  • Benicia, California
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Crosman 1377 - HoRodded 10 FPE
Diana Model 27 (childhood airgun)
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Motorhead

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Re: Unbalancing the JSA SS valve and using it regulated.
« Reply #5 on: December 01, 2018, 08:59:58 AM »
Just an FYI .... My intent was not to bait interest and then hold back parts to do it ... simply don't have the miens to produce in quantity custom poppets using a small manual lathe.

I can't  speak for the manufacturer and would think this is really not a bad thing at all ... just an alternative set up configuration that allows a dual role for this established valve.
One can only hope JSA see's this as a positive "Ah Ha" moment and realizes providing an alternative non balanced poppet is a good idea ???

Honestly this is just evolution and continued R&D on our beloved PCP's & not a dig or defamation to those who developed this valve.

Scott S
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