Cyma AK

[emit]

Hi,

During the last skirmishing session my CM045 seemed to lose considerable power. 

 

I opened it up and found the cylinder head was worn out. Replaced it and the nozzle and it works great now.

 

 

 

 

Edited September 11, 2022 by emit

[Skara]

If ALL the compression parts inside the gearbox seal (so: piston head to cylinder, cylinder to cylinder head, cylinder head to nozzle in its fully extended position) then the issue is most likely around the hop up area.

Check if your nozzle to hop rubber seal is good, install the gearbox with the nozzle at its resting position (fully extended) inside the gun, then shine a light down the muzzle and check if there is any light coming through the hop unit's feed tube.

 

If there is, then your hop rubber is worn/torn or the nozzle is too short. Replace accordingly. If your nozzle doesn't have an o-ring, replace it regardless, make sure to measure its length with a caliper and buy accordingly.

 

DO.

NOT.

USE.

PTFE.

TAPE.

TO.

SEAL.

COMPRESSION.

PARTS.

[Tactical Pith Helmet]

What @Skarasaid.  If the motor spins OK it's your air seal.  There are a plethora of nozzles etc available.   

 

As a comment on airsoft aegs, just look at the spring in the above photo's.   Sloppy as fuck with a loose guide and a mean twist on the fifth to fourth coil.  Efficiency is not designed into this at all.  No offence to the OP, hope you fix your rif.  

[emit]

Thanks for the tips!

With the nozzle extended I can't get any compression in the cylinder. 

I ordered a new nozzle of the same length and a new cylinder head just to be safe.

I noticed some wear on the nozzle of the cylinder head and a difference in external diameter from 5.2mm nearer the tip but not at the very end and 5.3mm in the middle.

I'll report back once the new parts are installed.

Edited June 4, 2022 by emit

[Adolf Hamster]

Worth noting that whilst sure it aint pretty or "proper", and not something you'd expect a decent tech to do, ptfe tape does work for the cylinder head when done neatly.

 

One of those bodges that does at least have some basis in reality for those who only care about the result and don't worry about the next guy who has to open the box.

 

Generally with the cyma's air seal is what i'd gravitate towards as an area to be addressed. A nozzle with a sealing o ring is a good shout for any box that doesn't already have it.

[Nine-Ball69]

On 03/06/2022 at 09:55, Skara said:

fdafdsg

 

Does teflon tape actually not work for compression? Even when it's used to *improve* compression being wrapped around a hop-up packing and the inner-barrel? I've heard that dental-floss isn't the best choice, but I didn't know that ptfe tape isn't advised.

[Lozart]

47 minutes ago, Nine-Ball69 said:

 

Does teflon tape actually not work for compression? Even when it's used to *improve* compression being wrapped around a hop-up packing and the inner-barrel? I've heard that dental-floss isn't the best choice, but I didn't know that ptfe tape isn't advised.

 

It works on the hop rubber if you have a particularly high FPS build (sniper rifles and the like) but not where most people use it - in lieu of replacing a cylinder head o-ring.

[emit]

I tried installing the Rocket cylinder head and nozzle. The cylinder head was too tight for the stock cyma cylinder and it ripped the o rings so went back the original head, loads of silicone grease and the rocket nozzle. With the gun assembled it seems to shoot well again other than the fact that it only shoots auto with the selector in the full auto and semi.

I really don't enjoy the drama that follows every time I open and aeg gearbox. 😔

I'll have to open it up again to see what is preventing it from semi fire.

[Adolf Hamster]

11 minutes ago, emit said:

 other than the fact that it only shoots auto with the selector in the full auto and semi.

I really don't enjoy the drama that follows every time I open and aeg gearbox. 😔

I'll have to open it up again to see what is preventing it from semi fire.

 

i'd assume the selector plate teeth aren't lined up quite right, very common issue thanks to the rube-golberg setup the v3 box has for a fire selector.

 

one thing i find helps is to insert the gearbox with the reciever lying flat on the left side, let gravity hold the components in place whilst your sliding it into position.

[emit]

Thanks, it was indeed slightly missaligned by one tooth.

All working as expected for now.