I'm wondering if anyone else has experienced this issue. I have a fairly new Impact MKII in .25 cal. and I have had the following problem happen a couple of times now on 2 different tunes. Example- gun will be shooting @ 900 fps on max hammer spring adjuster wheel and 4 lines on valve adjuster, will suddenly start shooting at a much slower speed say 800 fps, adjust wheel to 5 same speed, adjust wheel to 4 same speed, gun will also sound like it is shooting with less power. Turn the valve adjuster in to 1 line and then back out to 4 lines and gun will go back to shooting @ 900 on max. I have removed valve adjuster and polished the spring (looked like they were cut with hacksaw from factory) and it has happened again. I can't see where the spring would get hung up to cause this. Gun is tuned correctly with good balance between reg pressure, hammer spring and valve spring. Any advice on this would be appreciated.
Tuning Impact MKII Valve Adjuster Issue
- Thread starter gbikerman
- Start date
Hard to say. It could be a loose C1. That sounds like a good possibility or a good place to start.
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Definitely could be a C3 comeapart ? But The max hammer and good tune part have me questioning just that? Not really enough info, what pellet are you pushing 900? What barrel length? Just seems there is common problem with all the info out there, max hammer spring and 110 bar on the reg,= barking like a dog
Total assumption! And extremely common unfortunately, good/bad part is, these guns shoot really well, really jacked up!
good luck
Total assumption! And extremely common unfortunately, good/bad part is, these guns shoot really well, really jacked up!good luck
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Agree not much info to go by. I can say when no change in velocity from max to 5 to 4 etc, the hammer spring is for sure over sprung. If tuned correctly you should be seeing a decrease in velocities as you go down on the PW. Also not sure if older model with the C3 bumper or the newer hammer with C3 built-in, but certainly if with the C3 O-ring, that's the first place to look for a deteriorated C3 O-ring.
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Here is some more information. As stated in original comment gun is new MKII. It has the Power Plenum so no C3 bumper. Here are the settings for the 2 tunes that this has happened on.
From Talon Tunes
Reg @ 105 BAR
Hammer .690 at Max
Valve .380
Speeds Max-965 5-958 4-946 3-932 2-900 1-870 min-849
Tune 2
Reg 97 BAR
Hammer .745 @ MAx
Valve .380
Speeds Max-920 5-914 4-890 3-870 2-833 1-797 min-767
Gun tuned @ 70 F.
Tunes are at the Knee of power curve. Gun will shoot consistently (SDV) of <3FPS. Gun shoots these speeds consistently and then will suddenly drop speeds considerably. After speeds drop, turning the power wheel from max then 5 then 4 will not change speeds. Nothing on gun has change, Reg Pressure is same, hammer is same, and valve is same. If I then turn in valve adjuster to say line 1 and right back out to what it was set at the speeds will return right back to what the gun was tuned for. If I don't do this with valve adjuster the speed will remain low. There is no rhyme or reason to this, it will just randomly happen. Just wondering if anyone has had this happen to them.
From Talon Tunes
Reg @ 105 BAR
Hammer .690 at Max
Valve .380
Speeds Max-965 5-958 4-946 3-932 2-900 1-870 min-849
Tune 2
Reg 97 BAR
Hammer .745 @ MAx
Valve .380
Speeds Max-920 5-914 4-890 3-870 2-833 1-797 min-767
Gun tuned @ 70 F.
Tunes are at the Knee of power curve. Gun will shoot consistently (SDV) of <3FPS. Gun shoots these speeds consistently and then will suddenly drop speeds considerably. After speeds drop, turning the power wheel from max then 5 then 4 will not change speeds. Nothing on gun has change, Reg Pressure is same, hammer is same, and valve is same. If I then turn in valve adjuster to say line 1 and right back out to what it was set at the speeds will return right back to what the gun was tuned for. If I don't do this with valve adjuster the speed will remain low. There is no rhyme or reason to this, it will just randomly happen. Just wondering if anyone has had this happen to them.
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I've got nothing. Maybe a bent valve rod that is rotating to a bad spot or something along those lines. I would probably run this one by FX and see what they say.
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I'd ask, what is on the end of that "valve adjuster"? Is that the part with a rubber ball on it's end? I'm not an impact owner so I don't know but seems I've read somewhere about the part on the end of that adjuster getting loose.
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sure sounds like the C1 under the valve adjuster has come loose to me. The odd part is, nothing but a declining shot string when it is in this condition. I would pull the valve adjuster completely off after degassing the impact. check and verify that the c1 is set to 6.5mm and look for any burs in the c1 in itself and look in the valve body as well. seems like the C1 is sticking in the valve body. because it seems to go back to normal once you screw the valve adjuster in (pushing the c1 out of a bind spot) and it goes back to normal till it hangs up again.
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This brings up a thought about another post recently where a rubber ball was added in from either a PP kit or a slug kit, but the factory already had the rubber ball installed. This would be the rubber ball that goes inside the valve spring as a safety measure with the newer valve spring configuration. They were getting erratic behavior then removed the second rubber ball for the fix.
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Thank you everyone for your input/help. I am going to check the C1. That sounds like the most likely culprit. I will let you know what I find.
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dannya1a your the man! C1 was very loose causing slight misalignment that caught the spring not allowing correct compression of spring. Much thanks!!
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Your welcome. I had a similar situation with mine and that was what cured my issue. My c1 had come lose.
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