Kral valve porting
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Kral valve porting
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Topic: Kral valve porting (Read 330 times))
BeauJames
Plinker
Posts: 161
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Real Name: Beau
Kral valve porting
«
on:
October 19, 2021, 10:40:27 AM »
I’ve been hesitant to open my valve throat on my guns in fear of ruining a valve and not being able to replace it. I purchased some used Kral parts on AGN, and they came with a couple valves so now I have a backup.
Real green on this. Ive got two big drill presses with vises at work. Ones a Jet and the other is a big green cast iron monster, don’t know the brand. Ive got a puncher breaker in 22, and a NP02 in 25/22. Ive had the breaker apart many times, and know my way around it pretty good, and I’ve got notes from this forum on port sizes.
What’s the process to opening up the valve? Just gut it and chuck it up in a vise? I’ve got a full set of quality brand new bits to use. Do I have to change anything else with my valve because I went bigger. I believe .231 was the throat size to shoot for, will the factory poppet hold up to that size? I still have to do my transfer port also, but i think I’ve got all the info needed to do it, kinda need an upgraded power adjuster. TH!
Thanks for any and all help!
Beau Moody
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USA, Oklahoma, Locust Grove
Lani52
First to break 600 yards with 12 oz cola can
Expert
Posts: 1664
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Real Name: Roachcreek
Re: Kral valve porting
«
Reply #1 on:
October 19, 2021, 11:35:01 AM »
That seems a bit large.
I do not have a puncher, but I did port my Krat0s, which is a Kral. So maybe this will help. You need to open up the following ports, the valve port, the receiver raceway/port , the power adjuster port and the barrel port.
On the valve it is straight forward, but it gets somewhat complicated from there. I used a .156 at first and later went to .187. Using the .187 will mean that you will need to drill and retap to 1/4-20, the rear barrel set screw hole, this is your access hole for the receiver port once you remove the barrel, as the .187 drill bit will remove the oem threads. The barrel, like the valve again is straight forward, chuck it up in a vice, set your drill bit depth and drill.
The power adjuster, if your Puncher has one, is where you run into a bottle neck. It is difficult to open that port without damaging the power adjuster shaft where the port is located. I used a small round Swiss type file to carefully open it up, but did not go for the full .187 hole, it is instead around .170. This is where the spare parts come in, I had on hand a spare power adjuster. After the .170 file hole, I decided to push the 2nd pw port larger and ruined it, so be careful.
I also removed a couple coils from my valve return spring, this seems to always give a 20 to 35 FPS boost, but will not work on a regulated gun as the regulators fill too slow to seat the valve poppet consistently, at least the case on my Altaros regulated Kratos.
This increased my unregulated FPE from 45 FPE to 53 FPE, with Kings it meant 875 FPS to 960 FPS, with 48 grain slugs 9t went from 660-670 FPS to 710 FPS.
]Hope this helps,
Roachcreek
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Usa Great Basin high desert
Roachcreek 615 yard shot 257 Haley 12 oz cola can Airgun-utube
Prod, Exclusive sidelever breech MMTJ barrel, Blue fork trigger group AR stock magpul forearm 16 “ shroud with AR birdcage Flash hider
Bulldog ported to .30, heavy spring 260 FPE/178 grain thru the magazine
Skyhawk, JSAR LW Poly choked barrel .22/45 FPE Huma reg Lee545 plenum and shroud
Airforce Texan 257 lss MadDog stock, cf .5L bottle ,no vrs, 25lb Hammer spring
Benjamin Kratos 25 .5L CF bottle
Hatsan Spark compressor
Molds: NOE 358-152, 257-420BT, Accurate molds 358-122 Lyman 358-429, 257420
Altaros Booster pump run by TWO CAT compressors
TroyHammer
Expert
Posts: 1058
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Real Name: Troy
Re: Kral valve porting
«
Reply #2 on:
October 19, 2021, 12:24:03 PM »
Don't touch the throat it's plenty big enough. In 22 I use 11/64" for the transfer port (valve to barrel) and 13/64" in 25. You'll need a new power adjuster and machine the breech to accept it to go 13/64" in a 25. The factory power adjuster will work fine up to 11/64". The rear barrel screw to access the TP is already 5mm so no need to do and retap on the Kral guns.
«
Last Edit: October 19, 2021, 12:26:06 PM by TroyHammer
»
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Ohio Cincinnati
TroyHammer
Expert
Posts: 1058
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Real Name: Troy
Re: Kral valve porting
«
Reply #3 on:
October 19, 2021, 12:28:30 PM »
I've also began to do the valve transfer port at an angle of 20° or so.
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Ohio Cincinnati
BeauJames
Plinker
Posts: 161
yes
Real Name: Beau
Re: Kral valve porting
«
Reply #4 on:
October 19, 2021, 12:52:01 PM »
So if I keep with .22 all I need is to pull the power adjuster and open the TP to 11/64. The factory power adjuster doesn’t need to be opened more? I’d rather go to the bigger power adjuster than try to open the factory. I’ve got the valve port, endcap, and barrel ported.
The variable speed drill presses will do a good job? Im sure there’s equipment that can do it better, but these are what I have access to and I like doing the work on them.
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USA, Oklahoma, Locust Grove
BeauJames
Plinker
Posts: 161
yes
Real Name: Beau
Re: Kral valve porting
«
Reply #5 on:
October 19, 2021, 12:59:39 PM »
Roach,
I used your info in past posts I’ve made to modify the gun. Just hadn’t gotten around to the TP, or the valve.
On clipping valve return springs in a regulated gun. If the plenum is large enough could it hold enough air to keep pressure high enough to seat the valve? The NP02 will have the bottle regulated and a 110cc I believe, front air tube that will act as a plenum. I have no idea what the pressure from one .22 cal shot would drop to.
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USA, Oklahoma, Locust Grove
TroyHammer
Expert
Posts: 1058
yes
Real Name: Troy
Re: Kral valve porting
«
Reply #6 on:
October 19, 2021, 05:07:58 PM »
If you need help on a larger adjuster let me know. I've done plenty. I make them from a hardened 8mm hex head bolt. They still function like factory.
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Ohio Cincinnati
BeauJames
Plinker
Posts: 161
yes
Real Name: Beau
Re: Kral valve porting
«
Reply #7 on:
October 19, 2021, 05:48:52 PM »
Troy, yes I do need help with one. I was hoping you would have one for sale soon. I’d like to make my own, but have no way to turn the bolt down.
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USA, Oklahoma, Locust Grove
TroyHammer
Expert
Posts: 1058
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Real Name: Troy
Re: Kral valve porting
«
Reply #8 on:
October 19, 2021, 06:30:41 PM »
Here is what I make. Required the old hole drilled to 5/16"
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Ohio Cincinnati
BeauJames
Plinker
Posts: 161
yes
Real Name: Beau
Re: Kral valve porting
«
Reply #9 on:
October 19, 2021, 07:30:25 PM »
Yes I saw it in one of your YouTube videos. Very well done. If you’ve got any made up I’d like to get one from you. I’ll have a small lathe at some point, but I’ve been spending to much money on airgun stuff. I’ve got a couple machine shops I’ve had do some work for me. I’m sure if I gave them a stock power adjuster and the correct bolt to machine with proper dimensions they could do it.
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USA, Oklahoma, Locust Grove
Wickedwoods1
Shooter
Posts: 21
yes
Real Name: Eric
Re: Kral valve porting
«
Reply #10 on:
October 19, 2021, 10:43:01 PM »
Good work
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USA, NY, Clarence
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Kral valve porting