Well I finally decided to buy 2slo2ugly's JG beta spetz AK. I really liked it for some reason. I figured it would be an excellent loaner or project gun.

(*note: all small thumbnail pics can be enlarged by clicking.)

So I decided to make it into a low power CQB bb hose. I decided to take the element kit, short stroke the piston, swiss cheese the piston, rewire the gun with a basic mosfet and deans plugs, break in the gears and the motor. Reshim and retune the gearbox.
here she is before...


I bought an element full tune kit from ROman for 30 bux! So far I spent 90 bux on the gun.
here is the ELEMENT ftk...


The battery mike gave me was a 1200mah 8.4v NIcad battery. It totally sux . lol but the price was right so ehh.. here it is at full charge putting out a whopping 9.9v


The stock configuration measured at 305fps at 12 rounds per second.
(all measurements were made with guarder 2008 speedy chrono using killer beez .20 bb's)






obviously there was ample room for improvement.

I cracked open the gun and got to work. I use a white towel or similar when working on AEG's so that any parts lying around can be easily found. I also lay the parts and hardware together in an orderly manner so reassembly is headache free(for the most part lol)


The gearbox seemed to be of decent quality and it had an ICS motor. not bad. here is the stock gearbox...





Step one *gearbox overhaul*
I used carb cleaner to strip all of the grease from the gearbox and added the Element metal bushings which were a tight fit. I super glued them in place as well.
I then shimmed the gears and broke in the motor and then the gears using a tub of water and an old/weak nicad battery I have.

I also used a heat gun to expand the piston head o-ring a bit.






Be sure if you use the water method to break in your motor that you do 2 minutes reverse polarity and then 3 minutes normal polarity. when you are done you must get all of the water out. brake cleaner does this task extremely well.


Step 2 *short stroke the piston*

The factory piston head had a large weight on it. The element version has no weight added but does have ball bearings. In a high ROF setup, you may want to use a head that has no bearings to save weight. Since the element head was still lighter than stock, and the only one I had on hand, I used it.

I am only short stroking the piston by one tooth. you can remove even more, but remember you lose about 10-15 fps per tooth removed. You also have to cut teeth from the sector gear accordingly. (more on that later)

First I removed the steel tooth from the element piston. Then I used a razor and a dremel to remove the last tooth. I also had to make the channel for the last tooth longer so that it can slide back to it's new position.


In order for the metal tooth to slide all of the way back, you need to file down that stopper.


Now I need something to fill this gap. Notice that I left a small portion of the second to last tooth to help me line up the last tooth's new postion.



To fill the gap, I used another metal tooth and dremeled off that stopper to fit like so.




an easy way to avoid doing all that , is to simply buy a piston with more than one metal last tooth and file off as many teeth as you want so long as the last tooth is still metal.



next I swiss cheesed the piston a bit. I did not have a larger drill bit so this is a mediocre swiss cheese job.
When done correctly, swiss cheesing can increase ROF by 5%. This works because there is less overall mass for the motor to have to throw around.




Finally you must remove the 2nd tooth to ensure proper gear meshing at high speeds. This will ensure the longevity of the piston and MUST be done for a high ROF setup. here are some pics of that process...

[img]http://i7.photobucket.com/albums/y284/meancivicsi/th_IMG_4361Medium.jpg[/img]
[img]http://i7.photobucket.com/albums/y284/meancivicsi/th_IMG_4360Medium.jpg[/img]


whoo hoo , piston is finished! Notice the absence of the 2nd tooth!

[img]http://i7.photobucket.com/albums/y284/meancivicsi/IMG_4372Medium.jpg[/img]

Now I have to remove a tooth from the sector gear. I choose to remove one from the initial catch side to keep the tappet plate timing optimal, although for removing only one tooth, it doesnt make much difference which side.

[img]http://i7.photobucket.com/albums/y284/meancivicsi/IMG_4357Medium.jpg[/img]
[img]http://i7.photobucket.com/albums/y284/meancivicsi/IMG_4359Medium.jpg[/img]

Lastly I rewired the whole gun with teflon 16 ga wire, deans plugs and a simple 1404 mosfet setup.
[img]http://i7.photobucket.com/albums/y284/meancivicsi/IMG_4376Medium.jpg[/img]
[img]http://i7.photobucket.com/albums/y284/meancivicsi/IMG_4377Medium.jpg[/img]

used and angle grinder to cut the butt plate to allow external battery sources.

[img]http://i7.photobucket.com/albums/y284/meancivicsi/IMG_4393Medium.jpg[/img]



RESULTS!!!
ok now here is the improvements that resulted from all of that work.

velocity is between 322 and 315 now. This is surprising since there is a bad air leak between the cylinder and cylinder head. We also cut a tooth off which reduces fps. I guess the airseal improvements and bearing spacers bumped the fps up 30 fps or so over stock.

[img]http://i7.photobucket.com/albums/y284/meancivicsi/IMG_4407.jpg[/img]


test 1 8.4v battery 9.97v measured at time of test.
17-19 rounds per second that sux but is better than 12 rps!! lol

[img]http://i7.photobucket.com/albums/y284/meancivicsi/IMG_4389Medium.jpg[/img]

with the 9.6v powerizer battery( I know powerizers suck, but its all I had at the moment.)
24 rounds per second! not bad considering it only shoots 12 rps stock
[img]http://i7.photobucket.com/albums/y284/meancivicsi/IMG_4408.jpg[/img]

Over all the results are a step in the right direction. although I am a little dissapointed in the rof. next installment for this ak will be a...
- better motor but an ecanomical one. maybe guarder.
- better battery 7.4 or 11.1v lipo 12c-25c (economically priced one)
- capacitor bank setup
Thanks for reading any questions please pm me
[img]http://i7.photobucket.com/albums/y284/meancivicsi/IMG_4396Medium.jpg[/img]