Lol my .25 shorty never jammed either it did suffer a major pants pooping event. My ldc suffered the most from 350b valve dump. 
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Huben Any issues or problems with Huben gk1 please share your experience
- Thread starter windowtintz
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I seemed to have lucked out in this. My 0.22 GK1 is "true to size".
For yours, is the barrel is nominal size, but the magazine is oversized? (Mag holes are too large?) And that means pellets are too loose and move around in the mag and jam? What is the work around for this? Larger head pellets, or ones with wider skirts?
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Yeah the mag holes are slightly bigger on mine. The projectiles easily dislodge and can get caught on the barrel.
So far I've simply been shooting the same JSB pellets, which do fit. But Im thinking about replacing the magazine in the future.
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And Huben likes to change parts fairly often . Learned some v3 GK1’s had v3+ parts.
I ordered a V3+ upgrade kit from Wolfiek and also AresAGT. Ares is the latest and Huben is back using the brass valve again and buffered striker. Wolfieks kit had a full steel valve with a small hole in the striker w/ no buffer. Then theres the springs, original 7x31, K1 spring and new longer v3+ spring.
Funny .. my 3 GK1’s are all v3 and each had a different spring. Now .. All have the brass valve, buffered striker and K1 spring which imo works the best for me.
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Are you referring to the striker spring? I recently bought a GK1 parts kit, and I did notice that the striker spring provided is noticeably different than the one that's currently installed on my GK1 V1. The spring inside the kit is longer and has a lot more coils. Is that normal? Did they change the spring type along the way?
I seem to remember that some people had issues with the spring buffer getting chewed up over time, causing the spring to deform. Does it have anything to do with that?
I seem to remember that some people had issues with the spring buffer getting chewed up over time, causing the spring to deform. Does it have anything to do with that?
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My 2 GK1 V3 have spring guides of unknown plastic. But none in my GK1 V1 and the V1 spring is starting to look pretty beat up.
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I'm having same issues as kenjeepman. props to him for putting this work in. Mine is a 177 and I have a great 4 mag tune at 12ftlb pressure 300-110. I would love a good 1 mag tune shooting 16.1s at around 25ftlb but it starts blowing air, major fps jumping and wants to dump. Seams like the 25 is most efficient from my reading. Anyone else have a 177 shooting at higher power? I got the 177 for barn pesting at low power and plinking shot count. But it would be nice to have a good higher power one mag tune for larger vermin 
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I'm guessing it's forward as I didn't need to remove the rear cover to reset, just air it back up.
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Theres 3 springs in use. The original 7x31 spring thats also in the spare bag.
A slightly longer spring which is the K1 spring and the newest spring is the longer spring I assume you have.
My 22 came with the K1 spring and theres was also one in my parts bag along with the 7x31 spring.
The longer spring is supposed to be part of the v3+ upgrade but according to the email i got from Wolfiek.. later v3’s can have them too.
Ive had no luck with that long spring. All 3 my Gk1’s all have the K1 spring now and operating perfectly.
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Right now i have the jsb 16’s at around 15 ft lbs. 2 mags 20 down to 20 mpa.I'm having same issues as kenjeepman. props to him for putting this work in. Mine is a 177 and I have a great 4 mag tune at 12ftlb pressure 300-110. I would love a good 1 mag tune shooting 16.1s at around 25ftlb but it starts blowing air, major fps jumping and wants to dump. Seams like the 25 is most efficient from my reading. Anyone else have a 177 shooting at higher power? I got the 177 for barn pesting at low power and plinking shot count. But it would be nice to have a good higher power one mag tune for larger vermin
Hopefully this weekend i can up the power see if i can get a good 1 mag Tune.
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inside the firing valve.
A oring and peek backing seal.
I believe early valves were threaded together. Theres no way to screw/unscrew this valve if the case. Maybe pressed together? Def not made to ever come apart.
A oring and peek backing seal.
I believe early valves were threaded together. Theres no way to screw/unscrew this valve if the case. Maybe pressed together? Def not made to ever come apart.
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Ask Kelly if he has any of the bronze springs. They’re made of phosphor bronze which has a better fatigue resistance than most types of steel.
You may also want to try the bronze closing valve spring. It is a small diameter spring and much easier to compress than the steel spring.
***To be more specific, the weaker spring should allow for a flatter shot string at high power. This closing valve is more similar to a regulator than the power adjusting system in a conventional pcp. For instance, in a conventional pcp you want to increase spring tension to increase power. In the Huben you’re decreasing spring tension to increase power. Much like a regulator. In fact, early Hubens used a closing valve spring similar to the ones used in Lane regulators.
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Ive had the same issue where the firing valve would not close slowly letting out the air. Eventually sealing up towards the end of the tank.
I don’t like the newest spring they use, the longer one. The original spring (7x31) is known to deforn and cause issues. my 22 cane with the 2nd spring which is the K1 spring. wolfiek only shows the 7x31 spring for the GK1 so i grabbed two K1 springs (part #9) and run them in all 3 my GK1’s.
I dont know if you saw my post where the v3+ kit with the longer spring bowed out my rear cover, and badly deformed the spring.
What is odd, and ive yet to really get a answer.
The v3+ upgrade kit i originally got from Wolfiek, the striker has a spring side depth of .420, and thats with the longer spring.
The v3+ kit i got from AGT, striker depth is only .250.
they are both different types of strikers (one buffer other without buffer) but the depths should be the same. I cant prove it but i believe AGT’s should be .420 has well running the longer spring.
I just recently installed AGT’s v3+ kit in my .177 using yhe longer spring. The firing valve would randomly stick open and slowly let out the air, eventually closing before the tank was totally empty. I went and installed the K1 spring and all is well.
Interesting with the closing valve spring. I have a bunch and all are the brown coated springs.
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Very much so (acts) like a regular, been thinking this ever since i went down the rabbit hole learning how this think operates.
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Blue or white? huben has a multiple different donuts in use. Blue, white, thinner, thicker.
The original blue donut in my 25 broke apart a bit. The v3+ kits all have the thinner white donut .
I never actually compared the material used.. now curious haha
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Yeah the one inside the kit I ordered has the long darkgrey spring in it. I have an early GK1 V1. My original spring looks different than the two in your picture. It's about the same length as the bottom one, but with less windings, thicker wire, and bronze colored instead of darkgrey.
So the long spring doesn't work well for you? What happens exactly when you install it? Air dump? Underpowered shots? Or no shots at all?
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