CFX Tune

CFX Tune

Joined: June 9th, 2006, 3:14 pm

June 19th, 2007, 7:02 pm #1

I need some advice from some of you guys who are friends with the CFX tunes. Last year I got a Kit from Mich and tuned one. It was noiser than stock and after a few shots, the plastic spring guide broke. Rich wanted to eyeball it so off it went. He tuned it and returned. It was still noisy and after about 40 shots, the spring guide broke so I replaced it with a factory steel one...worked fine but still noisy so I sold it to a friend with no close neighbors. The noise wasn't dieseling, detonation, no smoke, and there was no combustible lubes anywhere near it. Never did figure it out.

So, I now have a new CFX and after about 500 shots, it's pretty quiet...a little spring noise and that's about it. But, I figured I should tune it like most of you owners do so I ordered a Super Tune kit and did it. Everything turned out fine, nice and smooth, but it was just like the first one...noisier than factory. Rich made a suggestion and I followed it with a re-tune. Didn't help. He made another suggestion and I re-tuned it again. Didn't help. The rifle is shooting 875/885fps, same as pre-tune but the noise is much too loud...it's more of a 'smack' than anything.
I decided to try changing the brass tophat Rich made so I installed the factory one...same weight. Didn't help the noise and velocity is the same.
I have another tophat that Rich made for the one last year which is drilled and is a bit lighter.
So, down to my question. What effect will the lighter tophat have...and do any of you folks have any good ideas. Neither Rich nor I have been able to locate the culprit.
BTW, after I finished this tune the first time I went outside and fired 3 pellets through it...I was greeted with the famous "Thump" I've heard so much about and I was delighted...FINALLY!! But when I started shooting yesterday morning, no thump...just noise.

Thanks a bunch for any ideas.

Bob
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Joined: December 29th, 2006, 4:23 pm

June 19th, 2007, 9:21 pm #2

I'm guessing by the super tune kit you received a JM E2000 spring. You made sure guides were a snug fit as well as the appropriate amount of velocity tar was added?(kinda a gray area, add to lil you get more noise, add a lil more you get slower velocity, and add to much, you risk getting it in the comp chamber).. If so you might try stuffing the stock with memory foam to deaded those vibrations which in return should help out with noise. Shouldn't be any movement in the rear plug, so you can cancel that out. Piston must have went in tight, if those are the figures you obtained from a chrony. Kinda strange you ask me. I have two kits from Rich and was amazed by the difference in spring sound and action. Never had anything break and have lasted rather well so far. Last case scenerio, you could put about 2000 rds thru it, if that doesn't help atleast you'll get adjusted. Good Luck.

Matt
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Joined: June 9th, 2006, 3:14 pm

June 19th, 2007, 10:00 pm #3

Thanks Matt. No, it isn't spring twang. In fact, there's zero noise from the spring, but I can't tell where the noise is coming from. It sounds kinda like the piston slapping the loading port area, but probably isn't. It just isn't that "thump" everyone talks about and that I heard when I first fired 3 shots after tune.
Rich says maybe I'm expecting too much, and he may be right. One thing I wasn't expecting is more noise post-tune than pre-tune though.
I'd sure like to shoot a CFX that's been self-tuned and does exhibit that 'thump' sound.

Bob
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Joined: May 12th, 2001, 1:29 pm

June 19th, 2007, 11:14 pm #4

...(e.g., the cocking lever) slap around and produce the noise you're hearing?

What about the loading port, when it's struck by the piston at the end of the firing cycle?

Steve
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Joined: December 29th, 2006, 4:23 pm

June 19th, 2007, 11:25 pm #5

Not to be a smarta$$ but ya made sure to put the lever shoes and rollers back in?...

Matt
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Joined: June 9th, 2006, 3:14 pm

June 19th, 2007, 11:32 pm #6

Yes Matt, I sure did put those goodies back in. I've had this rifle apart about 6 times now and have established a routine so I don't forget anything.
I don't think any loose linkage could be the culprit. I like to keep things pretty snug.
I don't know if it's the loading port or not, but the seals are tight and I kinda doubt it.

Bob
Last edited by robot2 on June 19th, 2007, 11:34 pm, edited 1 time in total.
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Joined: November 30th, 2006, 5:32 am

June 20th, 2007, 2:47 am #7

My B20 and B30 made obnoxious noise, even after good lube tunes. I casually bedded their actions and put bedding pads along the front of the action, along the forends. The twang is just about gone, both of them are real thunkers now.

I stuffed foam into the inner stock recesses of my .177 CFX too, but without bedding it yet. Twang is reduced, but I'll bet bedding it (and the new .22) makes a big improvement.

What I think happens, is the dynamics of the spring/piston/pellet/gas movement resonate through the stock, especially on an underlever or break barrel rifle, so the split forend becomes kind of a tuning fork. The more that vibration is dampened, the less twang there will be. Might even help them shoot straighter.

Joe C
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Joined: June 9th, 2006, 3:14 pm

June 20th, 2007, 3:19 am #8

Thanks Joe, this is something to consider. I've already stuffed the stock with foam and it may have helped a little...hard to tell. I'll test your idea tomorrow by straping the forend good and tight to prevent any vibration and see how she sounds.
Funny I haven't heard from anyone who has a self-tune that still has that famous "thunk" sound.

Bob
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Joined: February 14th, 2006, 4:12 pm

June 20th, 2007, 3:30 am #9

I need some advice from some of you guys who are friends with the CFX tunes. Last year I got a Kit from Mich and tuned one. It was noiser than stock and after a few shots, the plastic spring guide broke. Rich wanted to eyeball it so off it went. He tuned it and returned. It was still noisy and after about 40 shots, the spring guide broke so I replaced it with a factory steel one...worked fine but still noisy so I sold it to a friend with no close neighbors. The noise wasn't dieseling, detonation, no smoke, and there was no combustible lubes anywhere near it. Never did figure it out.

So, I now have a new CFX and after about 500 shots, it's pretty quiet...a little spring noise and that's about it. But, I figured I should tune it like most of you owners do so I ordered a Super Tune kit and did it. Everything turned out fine, nice and smooth, but it was just like the first one...noisier than factory. Rich made a suggestion and I followed it with a re-tune. Didn't help. He made another suggestion and I re-tuned it again. Didn't help. The rifle is shooting 875/885fps, same as pre-tune but the noise is much too loud...it's more of a 'smack' than anything.
I decided to try changing the brass tophat Rich made so I installed the factory one...same weight. Didn't help the noise and velocity is the same.
I have another tophat that Rich made for the one last year which is drilled and is a bit lighter.
So, down to my question. What effect will the lighter tophat have...and do any of you folks have any good ideas. Neither Rich nor I have been able to locate the culprit.
BTW, after I finished this tune the first time I went outside and fired 3 pellets through it...I was greeted with the famous "Thump" I've heard so much about and I was delighted...FINALLY!! But when I started shooting yesterday morning, no thump...just noise.

Thanks a bunch for any ideas.

Bob
if its not aligned.
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Joined: December 29th, 2006, 4:23 pm

June 20th, 2007, 4:01 am #10

Thanks Joe, this is something to consider. I've already stuffed the stock with foam and it may have helped a little...hard to tell. I'll test your idea tomorrow by straping the forend good and tight to prevent any vibration and see how she sounds.
Funny I haven't heard from anyone who has a self-tune that still has that famous "thunk" sound.

Bob
My shadow has that wonderful thunk since the home tune, it's not a CFX but pretty much the same (besides port size and the whole fixed barrel). After the tune it was almost angelic the way she sounded compared to the before sssspppppooooiiiiinnngggggg.

Matt
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