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Joyfull69

Cyma M14 low fps

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Hello All,

 

I have had a CYMA M14 for around a year now, have only played with it a couple times as I have too many guns, I decided to crono them all the other day and noticed that it was only firing around 260FPS.

 

Since then I have opened it up, and noticed the Piston had lots of wear, so  replaced that, I have also put a new m120 in , cleaned and re lubricated everything, new orings, put her back together and even with the improved airseals I was only seeing 290FPS, any help would be greatly appreciated.

 

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Change the hop rubber. 

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And bind the rubber to the barrel with some plumbers/ptfe tape a bit like this:

 

Helps with air loss and consistency.

8bc9a1_d992650ebfe54dad84da9a31c8a12c7d-

example is a VSR barrel but the same principal applies.

 

 

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Thanks for responding, I opened her up and went to the hop up, the bucking looked in good condition don't think I need a replacement, I did  put ptfe on it, but this didn't improve the fps by much at all( maybe 10fps), I have decided to order a new air nozzle as the stock one doesn't have an o-ring, when this arrives I will install it,

 

I'm looking to get it shooting as close to 400fps as possible, any information or upgrade ideas would be greatly appreciated, 

 

 

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You didn't mention in your OP if you did actually test the compression with your new O-rings, both with and without the air seal nozzle? Some times your setup will just call for a different O-ring size - definitely test this before installing the new nozzle.

 

Taking some material off the front face of the tappet plate can also help create a better seal onto the BB by allowing the nozzle to seat slightly further forward in the hop chamber at the point of shot cycle completion. Arguably this could potentially compromise the durability of the tappet plate, but sometimes you gotta do what you gotta do.

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I definitely could have worded my op better, the compression between the Piston, cylinder and cylinder head are great, I didn't even think about the air nozzle the when I first opened it, but there is a huge airleak from it, I'm hoping with the new one I will no longer have the issue, as I would definitely prefer not to shaving bits off 😂

Link for the air nozzle Bellow

 

 

https://www.amazon.co.uk/gp/aw/d/B00AAZCU8U?ref=ppx_pt2_mob_b_prod_image

 

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1 hour ago, Joyfull69 said:

I definitely could have worded my op better, the compression between the Piston, cylinder and cylinder head are great, I didn't even think about the air nozzle the when I first opened it, but there is a huge airleak from it, I'm hoping with the new one I will no longer have the issue, as I would definitely prefer not to shaving bits off 😂

Link for the air nozzle Bellow

 

 

https://www.amazon.co.uk/gp/aw/d/B00AAZCU8U?ref=ppx_pt2_mob_b_prod_image

 

 

Yeah that should be fine, it has an internal o-ring too which should take care of that leakage - just check that with the o-ring installed the nozzle is still able to freely slide up and down the cylinder head without too much friction.

 

In the event that you do run into that complication:

 

 

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The air nozzle arrived and as predicted it is to tight, will be fixing that tonight, has an incredible airseal now, but no movement 😂 will update when Im done, thanks a lot 

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Any feedback after installing the nozzle JoyFull? Having teh same problem after many upgrades. 

Out of the box CYMA M14 (long) (with M120 spring) - 348 fps

- Inner barrel 500mm 6.03 - Modify Hybrid 
- Bucking - Modify
- Cylinder head  - ASG Ultimate 
- Air nozzle - Guarder (later changed for metal one with O-ring SHS to guarantee seel)
- Conical piston head (silencioso) - SHS/Rocket 
- PIston with 15 metal teeth - SHS/Rocket 
- Metal spring guide with bearing - ASG Ultimate 
--Shimming 

Bought new Guarder gears but one of the gears has a slightly larger diameter therefore not installed.

AFter 373 fps (headache)

MY tech went over everything three times to check.

Installed new M130 Spring (No change to fps)

Need help, as scratching head on this one. Should be putting out on average 425 fps

Appreciate any comments



 

 

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I would love to help, was trying to get mine to just under 400, but just wouldn't happen with my m120 no matter how good an airseal ,  I have just put mine away, will just be leaving it at 340FPS, which isn't all bad I can keep full auto🙄, I have started a new project now so won't be opening my M14 till something breaks or I add the MOSFET,  if you do manage to get it to a nice 400, I would love to hear about the finale hurdles, sorry I couldn't be of more help.

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18 hours ago, JungleJug said:

Any feedback

Conical piston head (silencioso) might be one problem. Try with the original in it. The silencioso doesn't silenciose anyway. A sorbo pad does much better job, but that takes away some volume that you would need for such long barrel.

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On 13/03/2020 at 14:11, Joyfull69 said:

I would love to help, was trying to get mine to just under 400, but just wouldn't happen with my m120 no matter how good an airseal ,  I have just put mine away, will just be leaving it at 340FPS, which isn't all bad I can keep full auto🙄, I have started a new project now so won't be opening my M14 till something breaks or I add the MOSFET,  if you do manage to get it to a nice 400, I would love to hear about the finale hurdles, sorry I couldn't be of more help.

I'll let you know how things go. I changed out the 130 spring I had for a 120 SHS which was to hand. Strangely it went up to 380, so careful about the quality of your spring. I'm sure an M130 SHS will push it to 400+

On 14/03/2020 at 06:05, Samurai said:

Conical piston head (silencioso) might be one problem. Try with the original in it. The silencioso doesn't silenciose anyway. A sorbo pad does much better job, but that takes away some volume that you would need for such long barrel.

Thanks a lot, I'll certainly contemplate that. I'm on the hunt for a new spring so when I find I'll get the tech to do some tests 

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