Joined: Jun 2005 Gender: Male Posts: 2,601 Karma: 667
CYMA AKS74U Review « Thread Started on Oct 14, 2007, 11:21pm »
Finally got my hands on the brand spanking new AKSU of ALAKDAN last night. I had to restrain myself from working on it since I had agreed to do a fully documented review and upgrade session. I decided to wait untill morning so that I could get better quality pictures with daylight and give show you guys pics that would do this beauty justice!
Here we go...
Inside the box and "walk-around". She comes with a bakelite hicapacity magazine, a cleaning rod, a small pack of .20gm bbs, an 8.4volt stick type battery of approx 1,000mah capacity(according to my TLP-15 charger) and a wall-type charger.
Lets start at the business end of the AKSU and work our way around.
Here is a close up of the flashhider. The casting is a bit rough and lacking of fine detail, but generaly of good dimensions.
Looking into the muzzle end reveals that the inner barrel extends all the way to the apex of the cone of the flashhider. This gives her a few cms more of barrel length as opposed to other AEGS whose barrel terminates at the end of the outer barrel. The barrel sits snugly inside the flashhider and even has a slight "crater cut".
As you can see here, the simulated wood plastic foregrip looks quite realistic. It is also snugly fitted and doesn't have any creaking noises when handled.
Moving back, we see the beautiful metal body. All major components mate properly with no major gaps or seam lines. Finish is a dull matt black that seems fairly scratch resistant to normal handling. Everything is metal here! The only plastic you can see in the picture below is the screw cover on the safety/selector switch, the grip and the magazine.
The rear sling swivel is attached to the folding stock. It seems sturdy enough for actual use. My favorite feature though, is the way it fits loosely in it's mount and swings against the metal stock with a metalic sound as the gun is handled. Its a nice and subtle reminder that you're handling a metal bodied AEG.
Moving around to the other side of the AEG, we can see the release button for the folding stock. Again, the parts are all metal and the folding stock is held securely in the open position with barely any wobble. Its secure enough that I can confidently pick up the aeg by it's open stock and manhandle it.
Here you can see the "free" scope side-mount. Again, it is all metal and firmly secured to the receiver. Unfortunately, I did not have any side mounted rails/scope mounts that I could test with it for compatibility. In any case, its good to know that it's there if you need it.
Here is how the folded stock is secured against the body. It's also a metal catch and there is no rattling when the stock is folded. You won't be able to fold the stock this way if you attack a scope mount to the side mount though.
... to be continued...
« Last Edit: Oct 20, 2007, 12:32am by 9th[alakdan] »
Joined: Jun 2005 Gender: Male Posts: 2,601 Karma: 667
Re: CYMA AK74SU Review « Reply #1 on Oct 15, 2007, 12:16am »
Lets pop the hood...
The dust cover is hinged forward of the rear sight and does not detach from the AEG. It is spring loaded and once unlocked is held upright by the
spring. Be very careful though as this spring has a tendency to fly out if you open the dust cover too wide.
Seen from the other side, you can see the FUSE holder, and the way the wires are securely held by the gearbox top rail cover.
If you noticed above, the battery can go right through the trunnion block and all the way into the front foregrip. This allows the installation of even
higher voltage and higher capacity stick-type batteries. We can easily add 3 cells(for 12volts total) to the stock 8.4volt battery with room to spare!
Alternatively, 11.1 volt Li-Ion stick type batts and 11.1 volt "Chicklet" Lipo batt(1 cell inside handguard and 2 cells inside upper receiver) should fit easily.
Trust me, it goes all the way.
... to be continued tomorrow...
« Last Edit: Oct 20, 2007, 12:29am by 9th[alakdan] »
Joined: Jun 2005 Gender: Male Posts: 2,601 Karma: 667
Re: CYMA AKS74U Review « Reply #2 on Oct 15, 2007, 12:23am »
Time to work on the basic upgrade.
But before anything else, lets get the baseline performance of this AKSU.
Test fired using ToyJet .20gm BBs and the stock 8.4volt stick-type mini-batts.
ROF was pedestrian but playable and the accuracy was dismal but quite usable for CQB/Speedball type games.
Disassembly of this AK is pretty straight forward and used the basic TM/CA disassembly process.
Do be careful with these screws as they are tapped directly into the front barrel assembly material. If you strip these, then it's a messy job of having
the holes re-tapped for a larger screw.
Also be careful with the dustcover. Watch that it doesn't get extended beyond this position or else the spring might pop off- never to be found again.
Everything you see here with the exception of the hop up assembly is made out of metal.
Remove the selector level by removing the screw under this plastic cover(which is easily broken and easily lost in-game).
Remove the grip and expose the motor. This particular motor came unmarked but had a rather strong magnet. The magnet wasn't quite as strong as the ones
in the Systema Magnum or ICS Turbo 3000- but it was definitely stronger than any other ACM motor I've tried.
Here is our gearbox.
Items of note: - plastic bushings - black painted gearbox - abbreviated selector plate- doesn't have the electrical safety switch portion anymore - well organized wiring. - liberal application of thread locker(yes, this gearbox hasn't been opened since it left the factory) - correct type-2 cylinder
INSIDE:
Here is our first glimpse of the gearbox internals. Thankfully, nothing flew out when I separated the gearbox halves.
Closeup of the gears show the typical "overlubed" stat of China made AEGs.
The stock Version 3 spring guide doesn't seem to be durable enough for extended use- even with mild springs. So, out you go.
We replaced this part with an ELEMENT ver3 spring guide with bearing and we didn't have any problems fitting it in.
The stock nozzle seems to be made of the same material as the spring guide. It wasn't as effective as an air-seal nozzle with o-ring, but it was fairly
OK for our use.
We'll probably replace the nozzle with a decent airseal nozzle in the near future, but we wanted to see what kind of performance we could squeeze out of
the AKSU with only the very *basic* upgrades.
Here is a side by side comparison of the CYMA Nozzle with a CA nozzle. Length and diameter apear the same, though the CA nozzle has a smaller opening at
the outlet end. Probably for "venturi" effect.
I'm glad that CYMA did away with the previous cylinder head design which was also made out of the same material as the spring guide and nozzle.
Here is the gearbox after the gears have been taken out- revealing the plastic bushings and factory shims.
We replaced the plastic bushings with a 6mm BEARING BUSHING set from SYSTEMA. Although my usual practice would be to use bearings on the spur and bevel
gear only while using OILESS BUSHINGS on the SECTOR GEAR, this time- I decided to go ALL BEARING this time. Just for the heck of it.
The Systema bearings fit snuggly. I didn't have to hammer or force any of the bearings in. They were just tight enough to push in with my fingers. I
think it was mostly due to the black paint on the gearbox.
And now the Gears.
- they're made out of steel - the bevel gear has 5 cuts for the anti reverse latch - the sector gear has an enlarged tappet post- this allows less stress on the tappet + allows the bb chamber to be OPEN for a slightly longer period of time(yes, works just like a SECTOR CHIP). - one side of the sector gear and bevel gear shaft would not fit into the holes of the Systema bearings- I had to use a needle file and reduce the size of the axles a bit. - they sector gear had a slight "wobble" on it. I couldn't shim it properly with the SPUR gear since the distance between both gears would change depending on the position of the sector gear on it's rotation. I would hesitate to use strong springs with a gearset as wobbly as this(OTOH, the 2nd
AKSU I worked on this week had better gears-good enough for PDI190%) - no brand markings on this set of gears.
To be continued....
bedtime ko na...
« Last Edit: Oct 20, 2007, 7:50pm by 9th[alakdan] »
Joined: Jun 2005 Gender: Male Posts: 2,601 Karma: 667
Re: CYMA AKS74U Review « Reply #3 on Oct 15, 2007, 12:23am »
... final installment. Sorry for the delay.
Here is the trigger contact probe. Its only been through a few test shots with 8.4volts so there are no significant burn marks yet. It looks sufficiently built, but only time will tell if the metals used will stand up to higher voltage battery packs.
Here are the trigger contact prongs as well. I hope these are mounted on good quality plastic bases so that they won't meltdown when they heat up on higher voltage batteries(which I've seen happen with older CYMA AKs).
The piston head is already ported with 4 holes but there was already some sort of minor damage on the piston head as I opened it. It was secured to the piston with a metal spacer just like JG and TM piston heads. It still gave decent compression but I would realy love to change this with an aftermarket piston head with bearing or at the very least a stock TM/CA piston head(ported of course).
I only had a pre-used SYSTEMA M120 spring on hand and it gave me this chrono reading.
I have this nagging feeling that it should given me a bit more FPS but I wasn't sure if this spring was nearing the end of its service life and giving up the ghost.
Aside from the spring, I had my doubts on the integrity of the hop up assembly and the hop up bucking itself. Too bad we were in a rush to finish the upgrade in time for the weekend game. I would have loved to tinker with her some more and see if more FPS could be squeezed out of her without breaking the bank.
I plan to "borrow" some hi-end parts from Alakdan's other AKs to swap in/out with the CYMA stock parts in order to determine if there are any sub-par parts that could be improved with aftermarket parts.
Notably:
Hop up assembly Cylinder head and airseal nozzle Tight barrel Piston head
PS.. i got to work on another AKSU right after I began writing this review and there were notable differences between both units.
The 2nd AK had different gears- it came with the markings "www.gear.net.cn" stamped on the spur gear and the SPUR gear was of better quality.
The 2nd AK also didn't have any problems with the gears fitting into the bushings(element oiless) unlike the first one.
We put a PDI190 spring into the 2nd AK and we also replaced the piston head with an aluminum double o-ring piston head with bearing and installed a Guarder Air seal nozzle. FPS was slightly higher at 446 FPS but it was not *stable*. Apparently the barrel would move ever so slightly within the hop up assembly and we would get some air leaks. The problem *could* be fixed with a little ingenuity and elbow grease, but unfortunately we were again in a rush for the next game.
Joined: Dec 2005 Gender: Male Posts: 398 Location: PHIL0001.gif Karma: 1
Re: CYMA AKS74U Review « Reply #8 on Oct 24, 2007, 10:46am »
sir stan uhum im willing to let u play around with my ak para mafix yung mga probs niya just like the barrel that keeps on moving forward hehe para meron kna dag2 sa review mo
Joined: Oct 2007 Gender: Male Posts: 6 Location: PHIL0001.gif Karma: 0
Re: CYMA AKS74U Review « Reply #11 on Oct 26, 2007, 11:38pm »
maraming salamat, kasamang stan, sa iyong pagtulong sa mga komrads.
excellent review as always
the moving barrel, btw, is partly caused by the brass barrel spacer which is, ioho, medyo mas madulas kesa sa plastik na usualing ginagamit ng ACM replicas.
puede kayang pagbigyan mo pa kami sa isa pang pakiusap? aksyon piktyur mo at ng iba pang taga 1AD using the 035?
maraming salamat po ulit. hanggang sa muling pizza . . . ehe . . . pakiusap is what we mean
filAKas
« Last Edit: Oct 26, 2007, 11:47pm by filakairsoft »
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maraming salamat, kasamang stan, sa iyong pagtulong sa mga komrads.![[image]](http://filakairsoft.30.forumer.com/html/emoticons/filakairsoft/54.gif)
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hindi namin kayo kilala lahat so who's the other brader in the pic?