AEG Cycles 1 1/2 times
 

My systema mechbox had a crack (cracked, not snapped) in it so I ordered a new one, CA this time (version 2). My gun was still working fine up until I took it apart to switch shells.

Now, for some reason it almost does like a 150% cycle. I pull the trigger, the gears wind back, the piston releases and fires, then there's about a half second of gear cycle sound. "Weeee pooft wee" if you get me. I don't think that the "2nd cycle" really moves the piston around though, since whenever I take it apart it's never in a half locked position but in a fired closed position. Something does happen with the tappet plate and nozzle, however. This is the crappy part, because the 2nd mini cycle causes an extra bb to feed into the chamber so I'm always shooting out two. In fully auto it cycles normal until the last shot where it does the same 1.5 cycle.

I'm pretty familiar with my mechbox and haven't left out any pieces, but maybe I've made a silly mistake and assembled something wrong. Can anyone out there shed some light? Thanks.

Alex

Did you install the anti reversal stop latch propperly?

Yep, put in place properly, catches the gears if I try to spin them backwards. Also, it should be noted that all the internals are in pretty good condition. Only the piston is really showing any wear, but like I said, it was all working fine before.

Alex

How many latches are on you bevel gear?

Older design that only have 2 latches are known to double feed.
Systema still uses 2 in some model.
New TM gear have 4 now
Prometheus have 5.
Phoenix have 6.

I'm not positive, but I'm pretty sure it's 2 (they're systema gears). I'll check it out, but like I said, everything was fine with these gears earlier.

Since the beginning of this post and now, I have discovered a small chip of metal in my mechbox which is a tooth from my sector gear (reinforced my ass). It's the very first big tooth (meaning the first tooth that grabs onto the piston as a cycle begins). The gun still fires, but I'm willing to bet that's my problem. But, in case there's something else drastically wrong and this gear isn't my problem, well, all ears are open. Thanks again.

Alex

Sorry to get this post to the top again, but I've got EXACTLY the same problem. I had stripped gears on the piston and one on the gear that spins it back, so I changed those parts. The new piston didn't fit well in there, so I had to modify the exterior.

Now that everything is back in 1 piece, it does the little cycling after shooting, my anti-reverse has 5 latch. I think it can be somehow an electrical issue, as the motor spins a little more after releasing the trigger, causing the nozzle to back then come in to his original place. This causes double feeding, as it gets 1 BB in after the cycle(isn't supposed to), and one at the start of a cycle, just like it should.

Any one would help?!

Sounds like your cut off lever is sticky. It doesn't have to be too sticky either, it reacts in a very small amount of time, make sure it is very easy to move while still retaining it's spring retention.

I'll try (if I have time) to take it appart for a 3rd evening tomorrow, everything was working very fine before I take the mechbox in pieces, I have a game on saturday and I've got a backup from the game organizer, but I'd prefer my M16...

Does the cut-off as effect in full auto too?!

no, in full auto the cutoff is pushed away from the sector's cam by the little spring on thr tappet plate... i thought i told you that on msn lol

might be the custom spring you made... you should order that spring kit from airsoftparts... its alwauy good to have spares

Yeah I was wondering, I'll try to see if the electrical components aren't dirty or whatever, my custom anti-reverse spring shouldn't be related, as it doesn't affect the motor to spin more than it should...

If you have too big of a battery and too weak of a spring it can also cause over-rotation/an extra half cycle.

What bugs me is that everything was working fine before I open the mechbox, so it must be somehow related to the maintenance I did in it... Can't sleep because I keep searching for a possible reason of this failure lol... Thanks everyone for your ideas!

FYI, I've gamed it twice with this set-up, last game I've damaged piston's gear (but was still working after unjamming the barrel) and 1 tooth on the gear that spins the piston back.

9.6V shooting about 390 fps when installed the spring, 2 games ago...

yup my gearbox does the same, about 1,5 cycle on semi auto.... Gearbox works perfectly fine though... no problem at all.....

Fixed some of the problems, my custom anti-reverse spring wasn't strong enought, alowing it to back up.

Now my question: what is the normal starting position?! My gearbox does 100% cycle, but stops when nozzle is backed, as what I've seen it should be fully released in the hop-up unit, is my gearbox right?

Nozzle should be fully pulled back due to tappet plate spring.