VFC-clone AK gearbox airseal upgrades

[Cheeto]

Hello,

I've got a cyma ak-74 with a piston and air nozzle that doesn't seal.

Currently looking at getting the following upgraded parts :

-Cylinder head
-Air nozzle
-Piston head
-Piston

I would like to order all of these parts at once to save shipping, preferably from canada. I am quite worried with compatibility issues so I would like some help... let's say I have a 100$ budget for all of those, what would be a good setup ?

[paulwes83]

Hey man, if you want to get good answers out of this site then you have to get Age Verified (AV'd). Unfortunately, nobody will share information of where to buy things with you without your AV on here. Not trying to be rude, but this site has very strict rules for good reason.

Originally Posted by Cheeto

Hello,

I've got a cyma ak-74 with a piston and air nozzle that doesn't seal.

Currently looking at getting the following upgraded parts :

-Cylinder head
-Air nozzle
-Piston head
-Piston

I would like to order all of these parts at once to save shipping, preferably from canada. I am quite worried with compatibility issues so I would like some help... let's say I have a 100$ budget for all of those, what would be a good setup ?

[fleuryfighter]

Look for lonex or Shs parts. They are availiable in country. You can mix and match those brands and they work well together. Id suggest lonex over Shs but both are good options

^he never asked where to get them he asked what parts are good...

[paulwes83]

Originally Posted by fleuryfighter

Look for lonex or Shs parts. They are availiable in country. You can mix and match those brands and they work well together. Id suggest lonex over Shs but both are good options

^he never asked where to get them he asked what parts are good...

My bad, my apologies. Apologies too Cheeto, just always good to get AV'd as fast as possible so that you can find the best places to buy stuff from within Canada.

+1 to SHS and Lonex

[pestobanana]

Lonex Cylinder Head
SHS Nozzle
Lonex POM Piston Head
SHS 7 Hole 14T Piston

[Amoki]

... Or, just use superglue to build a layer on your cylinder head with your air nozzle and bring your piston + cylinder head to a seal/o-ring/gasket shop.

[Cheeto]

Ended up getting the following :

-ZCI type 2 cylinder
-Lonex cylinder head + 40D sorbo pad
-SHS air nozzle
-rocket airsoft piston
-Lonex POM piston head
-Lonex soft hop up rubber
-HS5 armory rhop patch
-ZCI 6.02mm tightbore barrel

Got everything from airsoftstore.ca I can't believe that won't solve my FPS consistency issues. Worst case scenario I will epoxy glue the cylinder and cylinder head together.

[Cheeto]

With the stock gearbox and upgraded barrel it shot @ 438-442fps with .2's

With the upgraded gearbox it now only shoots at 325 most likely due to the shorter piston course as the sorbo pad is interfering.

The stock spring is said to bay an m120 spring, I'ld like to get closer to 400, such as 370-390.

Can somebody suggest what the very best spring for that job would be ? m130 ? If so, what brand ?

[SawBone]

325 fps seems pretty low for an m120. I get around 360 with an m110 and I know my compression isn't perfect.

I'm not super familiar with rhop (none of my guns are), but I'd suspect a leak in your hopup. Try reassembling the hopup making sure the bucking is seated correctly, and/or try the stock bucking as a reference point.
It might also be the nozzle not meshing well the the bucking.

[Cheeto]

The rhop likely has nothing to do, I was shooting at 440 with it. The cylinder head takes far more place in the cylinder than it used to, therefore I believe there will be less air coming out of the cylinder which may explain the slightly lower FPS's.

[EOD Steve]

You have a large air leak somewhere.
Most likely between your nozzle and hop-up rubber.

With the nozzle in the most forward position, install the barrel against the mechbox, shine a light into the feed tube, observe the muzzle. If you see light, then you have an air leak.
Hop rubbers need to work well with hop units to present the correct profile for the nozzle to mate and form a seal. Certain rubbers "prefer" certain hop units, and also, prefer particular nozzles.

[Cheeto]

Originally Posted by EOD Steve

between your nozzle and hop-up rubber

Now we're talking, that just makes so much sense.

If you look at the pictures I posted in this other thread asking about the cylinder head measurements :

At one point I figured the pipe on which the nozzle rides was way shorter than the original one. It might seem like a bad idea to change the length of this part on a system that is working fine and I'm starting to think it most likely is. That probably causes the nozzle to deviate left and right a little more than it used to and cause misalignment with the hopup unit, causing different issues such as air leaks and maybe feeding issues.

I'm now considering greatly using the stock cylinder head with sorbo pad and epoxying it in place. Will try the head first and see if the FPS changes much then reply here to confirm.