Ak Burst Problem

[strykerles]

Recently purchased an G&G RK-74-E

 

stock Motor seemed a bit rickety so I changed it for a 22k infinity I had spare

 

fired fine on semi and fine on auto

 

when I switched from auto back to semi it started firing in 2 round burst in both modes

 

any ideas??

 

thanks

[Adolf Hamster]

2 round burst on semi is normally a symptom of going too fast.

 

possibly it's got itself stuck on semi only now?

[strykerles]

i'll try another 18k motor I have and get back to you

 

[Skara]

Could also be the mosfet.

 

They have AB by default but they're known for busting themselves into oblivion by just existing.

[Adolf Hamster]

25 minutes ago, Skara said:

Could also be the mosfet.

 

They have AB by default but they're known for busting themselves into oblivion by just existing.

 

hmm, ab on a 22k doesn't seem like it should double fire, if anything i'd be more worried about the opposite of it locking up.

[strykerles]

looks like the gearbox has had an attack, it's firing a single shot then a double now

 

think it may have had it

 

trying to find a v3 gearbox is a pain too lol

[Adolf Hamster]

if everything's cycling fine then it's not too massive an issue.

 

the selector plate setup in an ak is a ridiculous rube golberg affair so it's not surprising they can have issues.

 

i'd pull the box apart and have a look at the cutoff lever

[Sitting Duck]

Bit confused here....

 

It "sounds" like a possible COL but gun is new-ish or recently purchased

(but then 2 round burst on auto sounds odd)

 

Ahhh but it is an ETU fuck pig so that would explain a burst on auto

(but that would be 3rnd or potential 5rnd burst option on ETU2 units)

 

  

On 16/06/2020 at 18:13, strykerles said:

Recently purchased an G&G RK-74-E

 

stock Motor seemed a bit rickety so I changed it for a 22k infinity I had spare

 

fired fine on semi and fine on auto

 

when I switched from auto back to semi it started firing in 2 round burst in both modes

 

any ideas??

 

thanks

 

Now we know the common AK selector issue going from semi/auto/semi etc...

 

But this TWO round burst is a bit odd - should be 3 (and/or 5 round burst) on ETU I would have thought

but still get single shot semi & then 3 (or 5 option on blue etu2) or just auto on ergh auto

 

First of all - what battery are you using

ETU's can/do play up on 7.4v so best to run on 9.6v or 11.1v, (11.1v is best perhaps)

(normally, iffy etu's simply refuse to work on lower 7.4v, but wondering if lower volts causing an issue)

 

Secondly - RTFM (Read The Fucking Manual) for info about setting/changing the burst mode

 

COULD be an iffy ETU - the main unit near battery, as they are made from Dairy Lea

 

Turn off/disable the burst mode (RTFM) and start again so semi & auto operates correctly

 

In that sort of gun, I would have just used 11.1v with 18k motor to get you near say 20rps

and with the 22k you should be on or just a whisker over 20rps

 

It appears to be crane stock AK so assume the battery goes under the hood/dust cover

which this battery MIGHT be about your limit - but YOU need to check it will fit (inc wires)

https://hobbyking.com/en_us/turnigy-nano-tech-1300mah-3s-25-50c-lipo-airsoft-pack.html?queryID=c2ca5915ed20ee36fc43e6fc49de517d&objectID=31045&indexName=hbk_live_magento_en_us_products

 

RTFM, check your battery is OK, and give us a bit more info...

it might be a moody selector, but the etu causes more issues in some guns than it is supposed to solve

or if gun is still in warranty contact retailer (hmm good luck with that)

 

but I'm a little confused with 2rnd burst in both modes so if possible read manual, turn off burst etc...

and update us with a bit more info perhaps

[strykerles]

The gun isn't new, was someone's backup

 

Came with a 11.1 1450mah lipo

 

Opened up the box and it looks as though it needs a clean lol

 

 

[strykerles]

Put back together and it fired a few times in 2 round burst and then stopped, changed battery, motor etc and nothing, dead

 

Etu maybe?

[Skara]

8 minutes ago, strykerles said:

Etu maybe?

Most likely.

They're shit. The trigger board is fine but the fcu unit is abysmal.

[Sitting Duck]

Yup ETU 1 is red and the ETU unit is fucking wanked wanked wanked

Had a FFR2 A2, changed motor and it blew the ETU - WTF ???

 

Ripped it all out, old school trigger switch, 13:1 etc...

 

So me personally that is what I would do

or there is the option of Perun unit but it ain't ultra cheap....

 

https://www.taiwangun.com/en/wires-lasers/g-g-etu-upgrade-kit-perun?from=listing&campaign-id=19

 

 

 

Yeah it is very tricky to install (sarcasm) but supposed to work properly

 

http://perunairsoft.pl/products/gg-etu-upgrade-kit/

 

but me personally I'd rip it all out and go back to traditional old school trigger

coz G&G will still be a bit Dairy Lea, Perun won't leave you much change out of say £60 with shipping

 

and for that price, I could spend on 13:1, 25~30k motor, steel rack piston & cheap basic or diy (non burst bollox) mosfet

(you got 22k motor so forget the 25/30k motor, maybe 16:1 gears,

13:1's might be a bit too quick unless you short stroke on 11.1v

a couple of bushings under spur & maybe bevel, basic mosfet, normal switch,

steel rack piston (shs blue perhaps & cyma piston head or something that provides good seal, run on 11.1v sorted)

Well that is likely what I'd do but to each their own - but fuck G&G's ETU bollox imho

 

PS - looking at your pic, you might need a new COL, as it looks a bit different to reg v3 COL

(the lug that pops the reg trigger trolley looks to be set back to activate the micro switch on ETU trigger board)

 

 

see that wedge bit on right of arm, looks different to the G&G one in your ETU box

so a steel SHS COL might be needed to go old school, I noticed when I checked your pic - just saying

 

Before you do owt, test the board is completely dead by just having motor out of box

change fuse, but likely it is fucked

mine went a bit wanky, kept blowing fuses with motor out of box and got hot

 

yeah fuck that shitty unit right off I decided

 

[Skara]

I have the upgrade kit on my ARP and it's great..

Haven't really played with the settings, I have AB on and occasionally turn on binary trigger, which puts a big fat smile on my face when I'm playing cqb..

It's one of those overlooked bits that can greatly improve your gun without ripping everything apart.

[Sitting Duck]

1 minute ago, Skara said:

I have the upgrade kit on my ARP and it's great..

Haven't really played with the settings, I have AB on and occasionally turn on binary trigger, which puts a big fat smile on my face when I'm playing cqb..

It's one of those overlooked bits that can greatly improve your gun without ripping everything apart.

 

Pity G&G don't use them instead of Dairy Lea ETU units, especially on their higher price guns

nice to know it works well, but wish they was cheaper, even £50 inc shipping is a bit much

I'm being a bit miffed, but mainly coz the G&G unit is so shit

(some people have been lucky and works fine still even on 7.4v, but there are a lot of issues with ETU's)

 

Paying a bit above other similar guns, to then have to be faced with replacing something that is so defective

spending around £50 or so, or at least a tenner converting it back to basic trigger plus time/cost is a wank

 

G&G - lovely looking guns, but jeez some of their ideas & innovations have made matters worse not more reliable

 

G&G R&D dept: ETU design & testing...

 

The most annoying thing is that you can't just plug a basic mosfet in

due to the 4 thin wire lead, one is power, then a signal to each of 3 switches

(power, trigger, col switch & slector switch at back of trigger unit)

 

so the fucking thing is only for the ETU & can't drop a basic mosfet or warfet or owt in there

so you are faced with another Dairy Lea G&G ETU mosfet, luckily the Perun option but still not cheap

or rip the whole lot out and start again old school

 

real PITA these fancy bespoke units - especially with G&G's reliability (ultra sarcasm)

[strykerles]

think i'll replace the whole unit then

 

thanks for all the help

 

do you guys know any complete replacement boxes that aint stupidly expensive?

 

not mega confident in my skills to work on gearboxes

[Sitting Duck]

21 minutes ago, strykerles said:

think i'll replace the whole unit then

 

thanks for all the help

 

do you guys know any complete replacement boxes that aint stupidly expensive?

 

not mega confident in my skills to work on gearboxes

 

TBH you got an option to replace the ETU mosfet unit G&G £36 aprox if you can find one

or perun £50 inc ship from bravo/bullseye country sport in NI (good seller)

https://www.ebay.co.uk/itm/Perun-Airsoft-Upgrade-Mosfet-Kit-For-G-G-ETU-System-AB-LiPo-Ready-Burst-bbs/133377231128?hash=item1f0de70918:g:vv0AAOSwhQhehetA

 

OR contact Luke/Negative Airsoft perhaps

 

You could buy a V3 box, hopefully an AK with AK nozzle, trigger, selector and hope it fits OK

some v3's don't always simply slide into all other guns as is, at times a bit of modding required

(some will gladly take a std Cyma v3 & others will take a JG one but might need modding or vice versa)

those are two very common/cheap v3's out there, but there "might" be some minor fitting niggles to overcome

 

hence if you got a sound box that is compatible - stick with that and have it rebuilt (Luke or some other respected tech)

They can overhaul it and no doubt if old it is need of service and doubt if compression/seals are that great

Chuck in a basic mosfet, maybe the tiny perun

https://www.ebay.co.uk/itm/Perun-Micro-Airsoft-Mosfet/164224757298?epid=25036277200&hash=item263c8eee32:g:zngAAOSwP7ZdHKsv

 

So you can run on 11.1v, new col, trigger switch & some other bits n bobs

give it the once over and getting firing all dandy

 

yes labour & shipping issue, but atm you got a £300 when new gun that is wanked

so spending a bit of money WISELY is not such a bad thing

 

you can go nutz or Luke will advise you on the best cost effective course of action according to your budget

Or you can attempt to have a go yourself if you feel up to it, but will require some rewiring/soldering

or clean it up, slap some grease in there & buy the perun etu

 

those are the 3 options I would consider

(than buy a box that shoots too hot on an imported cyma v3 box & hope it fits first time)

[Sitting Duck]

On 20/06/2020 at 11:37, Skara said:

I have the upgrade kit on my ARP and it's great..

Haven't really played with the settings, I have AB on and occasionally turn on binary trigger, which puts a big fat smile on my face when I'm playing cqb..

It's one of those overlooked bits that can greatly improve your gun without ripping everything apart.

 

Don't know if you tried this but wonder if it is the reset to default option

or if it is a "Whoa fuck me - what ya doing bro" warning...

 

But the Perun ETU plays Michael Jackson - Smooth Criminal (Eddie are you OK) if you fuck about with it...

 

 

 

 

 

WTF  ???

[Skara]

Yeah I knew about it

I guess it's just a little easter egg manufacturers put into their FCUs

[strykerles]

In the end I thought "f*k it" and gutted the gearbox

 

replaced the piston, piston head, cylinder, trigger box, tappet plate and reshimmed

 

changed out the mosfet for the perun version

 

out of the gun it seems quite snappy

 

i'll put it  back together and see what we get

 

thanks for all the help @Sitting Duck @Skara

[strykerles]

think I need to reshim  the box again as it got a  little grindy

 

also the nozzle doesn't always come back after firing on semi  and  the selector doesn't seem to lock into safe properly

[Skara]

F

 

Shimming takes some time, as for the selector, no clue

[Sitting Duck]

4 minutes ago, strykerles said:

think I need to reshim  the box again as it got a  little grindy

 

also the nozzle doesn't always come back after firing on semi  and  the selector doesn't seem to lock into safe properly

 

shimming is a pita that you get better at the more you do it (hopefully)

there's loads of tutorials how to do it & some good/bad

a bit loose is better than bit tight

 

yes you kinda start with bevel to pinion but also attention to how the sector is shimmed

(roughly half/half spaced but attention it operates but no rubbing on COL or too high sector cam rubs on box casing)

plus attention to how the spur shims to both sector (swirl pattern if too close)

and attention to ensure plenty of bevel's 10 teeth mesh to spur etc...

(if bevel shimmed high & spur really low, little of 10 teeth mesh and stuff flies off or crunches under stress or mild lock up

 

so shimming is all about the spacing of gears/drivechain and how all the components engage as close to perfection as possible

(not always very easy to achieve)

 

IF you was on bushings I'd say a ROUGH BALL PARK...

 

Bevel - 0.2mm shim on top, no biggy about underneath

really not a massive biggy on JUST this gear underneath coz motor pinion ensures it ain't going far

(if you got a small shim left at end then take up some of slack if you wish to)

 

Spur/Step gear 0.2mm UNDERNEATH

(whatever is required on top to take up most of slack)

 

Sector gear 0.25mm to 0.3mm roughly so it sits a whisker higher than spur

(hopefully avoiding swirls from gears touching in rotation)

whatever on top to take up slack, should sit about half way spaced in box for sector gear

 

as you got bearings it is likely you might have a bit more lateral play than on bushings so add 0.05 to 0.10mm to these ref points

 

THE ABOVE IS ONLY A VERY ROUGH STARTING POINT, you have to adjust shit accordingly as each box & gears/build vary loads

 

check motor height with bevel in top half of box

 

on v3's a bit of shrill can be reduced by loosening the motor cage and slightly shifting it, tilting the motor angle slightly to mesh smoother

 

nozzle not returning - uhmm it doesn't always return 100% anyway in most instances

the nozzle begins to retract before the piston starts to retract & often the gun's cycle is slowed/stopped by piston retraction or rather the tension on spring building and slowing the motor

which means theif  nozzle often is at least partial retracted or even starting to release if running quick

(and on guns with plenty pre-cock the nozzle has returned already in preparation of firing/piston releasing)

so this nozzle fretting is not a big issue in "most" new tech concerns

 

obviously if it isn't operating or jamming then that is another issue but nozzle position is not (usually) a big concern

 

select linkage and stuff - yeah they are a bit of wank

safety is that triangle tab on gearbox that jams the 2 part trigger

the linkage is a git to get correct if the rear teeth are not aligned correctly

(and stay in place as you try to drop the whole thing back in receiver)

 

also clean & lightly grease and parts of selector/linkage checking they glide as smooth as silk

if any burrs, smooth them out and ensure it all glides/operates smooth as silk

stiff operation on selector mechanism shit will just mean more wear in linkage/selector components sooner

 

massive tip - take photo's on your phone - LOTS OF PHOTO's

then you will see how shit goes back together

in particular if a certain spring or component goes face down or face up

eg: a trigger trolley spring (you don't have one on etu) on reg setup v2 especially

can make a difference which way round the body of spring is placed or its orientation

(in the way the spring sits to clear the groove in the underside of tappet plate etc...)

 

on selector mechanism at rear - mark it with a pencil to ensure the marks re-align on assembly

 

or other shit like that - just a couple of examples

you takea pic or three will greatly assist in reassembly

[strykerles]

after the 5th attempt i believe I now have the shimming right

 

only problem now seems to be with the fire selector, sometimes it won't lock properly into safe and will click into auto when i pull the trigger

 

if i remove the dust cover it then allows the lever to go a bit higher and it's fine

 

sometimes too if I go from safe to auto it fires fine, then I go to semi and fire it's fine but then i go back to auto and it only fires in semi

 

I'm beginning to consider throwing this gun down the garden 😭

[Sitting Duck]

Linkage issue, likely one tooth out or wear

On a reg V3 there is the tab that locks the trigger solid

 

The iffy semi/auto is a common problem on AK's

Where linkage is worn or not quite correctly located

(It "could" be one tooth out on rear linkage

Or something is binding when box is refitted into receiver impeding its operation)

 

Investigate further, likely something stupid out of whack on reassembly

[Will-CS]

Just had this 'burst fire' issues on my G&G RK74-E.

 

The issue was the cut off leaver was in the incorrect position when I put the gearbox back together. When I made the adjustment both single and auto worked without any other work.

 

 

Just wanted to put there here in case anyone else has the same issue in the future!