I installed the power plenum upgrade a few weeks back on my .25 Impact X and was having a few issues with it. I reached out to Utah Airguns and they were awesome at helping me figure out the issue and getting me on track with tuning. Now I went to do a little shooting a few days ago and the gun is acting up again. I set my FX chrono up on the end of the barrel and started shooting. My intent was to verify yardage setting on my scope. The velocity was right around 900 but started dropping. The gun was full of air at almost 250 bar and my reg pressure is around 110. Even with full tank of air I kept seeing velocity dropping to down under 700. Even with bumping up the reg its till keeps dropping. I am getting frustrated. Not really sure what would cause this.
Tuning Impact X with power plenum upgrade issues
- Thread starter Arctichc
- Start date
When you say its speed is dropping. Is is slowly walking down? Like example #1 900, 890. 880, 850, 840,825, 800 ,775 etc. or is like example #2 910, 890, 905, 780, 890, 880, 900, 775 etc.. These are two different problems.
Example #1, dirty or damaged regulator piston and o-rings
Example #2, Hammer spring adjusted poorly, and/or the dwell adjustment to stiff
Example #1, dirty or damaged regulator piston and o-rings
Example #2, Hammer spring adjusted poorly, and/or the dwell adjustment to stiff
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Could it be the hammer seat is loose? if it slowly unscrews, the valve spring force should increase as the spring gets more compressed. It can be checked by unscrewing the valve adjuster body, and check with your fingers if it is loose.
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BTW increasing the reg pressure will not solve anything, it will only make the gun shoot even slower. If you look at this FX master class video https://www.youtube.com/watch?v=HDCIyO9mxmg&list=PLkrNvYFsp-t3NyUAi8sQicZBIVnQG_--O&index=10, you will know what the valve seat is. If it is loose you can try to fix it yourself by following guidelines, or get someone else to do it.
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This would be my guess too, it has about the same effect as when the slider set screw at the power wheel is backing off. (Which also could be the case here.)
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You know,, when I was doing the reassembly I wondered if i should have put pictures on that! Now I know. The tolerance on that end is from 6-6.5 if I remember correctly right?
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I just checked it before I started taking the gun apart and it’s measuring around 5.54 mm after I spun it back in
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That's ok. It would be worse when it is sticking out too far, otherwise the hammer can beat up the cocking pin in the sliding block because it has to travel further forward to open the valve.
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Back to drivin nails again boys!! Funny how something as simple as that throws these guns all out of wack. Thanks all for the suggestions!!
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