Cyma Cm.621 Upgrades

[Shamal]

7 minutes ago, Davegolf said:

Surely that just comes with being a mortician!?

Haha. I guess it's the fact that she is talking about it in a very bubbly way.

Most morticians are maybe seen but not heard.

Regards 

[Adolf Hamster]

35 minutes ago, alxndrhll said:

 

FTFY 👀

 

BURN THE HERETIC!

[Shamal]

58 minutes ago, Adolf Hamster said:

 

BURN THE HERETIC!

Ban him for tampering wiv da mail/post. Grrr.

😀

[Misery]

Well as some of you will saw from my staus last night i got her running hurrah.now to the firing she hits 90-100fps and is double sometimes tripple feeding and thats fully stock hop rubber and nub but im assuming thats more of a magwell issue??,deffo need to do the velcro on the magwell and i may just swap the lower of the 516 for it.now back to the fps am i right in assuming thats more gonna be a air seal problem and ill need to do the ptfe tape like sitting duck suggested?  other than that im loath to spend any on her as have decided to get my self another m4 or possibley a g36 *they have started to grow on me* and have her as a back up

 

also gonna take a ride 5 mins up the road tomoroow and speak to a local farmer and see if i can use the edge of one of his fields for plinking so i have a decent space to shoot in for testing and general practice

 

 

[Misery]

well after some scientific testing aka slapping the 516 upper onto the 621 it is not a mag issue but a hop issue so will have to get that sorted,which i will do when i sort the cylinder air leak

[Adolf Hamster]

8 minutes ago, miserydrift said:

well after some scientific testing aka slapping the 516 upper onto the 621 it is not a mag issue but a hop issue so will have to get that sorted,which i will do when i sort the cylinder air leak

 

you could try turning the hop all the way off then on a bit.

 

sometimes hop off gives a misleading reading as the bb starts rolling too soon.

 

it sounds similar to the issue i've had that was with ml rubbers and feedlips interfering with feeding, but iirc you said you'd pulled the ml rubber out for the stock one?

[Misery]

yeah reverted back to stock bud happens regardless of how much hop is applied so im beggining to thing maybe the hop itself is goosed

[Adolf Hamster]

1 minute ago, miserydrift said:

yeah reverted back to stock bud happens regardless of how much hop is applied so im beggining to thing maybe the hop itself is goosed

 

the hop unit itself should be fine, especially if it's original.

 

maybe a couple of pics looking into the feedlips/down the barrel might help in case there's anything obvious?

[Misery]

will get that done tomorow for ya for now gonna chill maybe whip out the shotgun and shoot some targets lol

[Adolf Hamster]

31 minutes ago, miserydrift said:

will get that done tomorow for ya for now gonna chill maybe whip out the shotgun and shoot some targets lol

 

fair enough, i forget sometimes that i'm the one not in sync with the rest of the world's sleeping patterns lol.

[Misery]

took the barrel clip off had a look noticed i had put the barrel in slightly off centre straightened it up and bam no more feed issues well using it on the 516 lower just low fps 200s instead of the 300's of the standard barrel but think thats cause its a tightbore on the standard cyma motor rather than the ones in the 621 charging a lipo so can test it in the 621

[Misery]

double feed issue sorted haha im such a noob llf now to fix the low fps issue which ill get some tape to sort cylindar out and fingers crossed that will sort that issue out

[Adolf Hamster]

hey we all had to start somewhere.

 

if you sort the compression and it's good with the usual checks then there's also the possibility it's blow-by at the hop.

[Misery]

i think i made another feck up lol the valve wasnt seated on the tappet plate so wasnt moving with it reckon that would cause the loss off compression?

[Misery]

and its sorted thank feck!! just need to velcro the magwell and seal the cylinder head with tape for better compression but she is now on par with the 516 now so im happy just need to mount my optic an  she will be golden well nce the other stuffs done lol big thank you to everyone that has helped me along this path of fixing the 621

[Misery]

well i think the mosfet has had it gun works intermitantly have cracked open the box as could smell a burning smell so have looked nothing seems fried etc but gun will only fire a round or 2 then have to unplug batt and reconnect so think i need to replace the mosfet thank feck its payday tomoz

[Adolf Hamster]

4 minutes ago, miserydrift said:

well i think the mosfet has had it gun works intermitantly have cracked open the box as could smell a burning smell so have looked nothing seems fried etc but gun will only fire a round or 2 then have to unplug batt and reconnect so think i need to replace the mosfet thank feck its payday tomoz

 

you've got the internal mosfet haven't you?

 

i'm not entirely sure if you can drop in normal trigger contacts to those cyma boxes but i'm sure duck will. but my preference would be for a "normal" mechanical trigger run to an external mosfet.

 

contacts are cheap enough got and a simple gate nanoasr is easy enough to chuck in with a bit of soldering.

[Misery]

yup that i do

tbf ive been pricing up perun mosfets i can get a drop in v2 optical one for 60 in my local airsoft shop so i may just get that so i can have her rebuilt tomoz lol and saves any soldering

[Misery]

perun mosfet and new trigger picked up now to install them

 

 

[Sitting Duck]

The thing the check is the top half of the box...

many boxes have extra material/lugs to steady ye old trigger trolley switch

your old 516 box flipped so top half is showing first...

 

 

on that 516 box which is slightly different to the 621 box

there are 2 larger horizontal lugs

followed by a thinner yet longer dash

also extra material around sector bushing area etc...

 

and stuff like this is where/why some fancy installs need a bit of dremel work

so the unit doesn't foul on the extra material...

 

now that is the 516 box

the 621 box has less extra material and seems to be less pronounced...

 

Pheas airsoft opening the 621 shows this...

 

 

 

 

Now the Perun has a rectangular " U " cut out of it on top half...

 

so it "should " not foul on some boxes - BUT REALLY NEED TO CHECK TO BE SURE

 

the lower part of unit should sit fine in the box

& the larger eyelet should slip into position OK (hopefully)

you just need to carefully with top half of gearbox - if any material/lugs risk shorting

or pressing/touching the unit when box is closed up

 

the only other thing to check if the two halves connect too closely

and/if your sector is shimmed way to high...

then the sector gear might rub on the sector gear sensor(s)

I think you will be OK but if you was using a chunky SHS sector gear and shimming high

then it needs checking or space the two halves with some thin foam to ensure clearance

 

 

(This from a cheap T238 install clip, but shows what I mean)

The little white rectangular sensors are a little pronounced on the pcb's

 

 

but Perun have ultra checked it for compatibility all the same in a number of boxes

so it "should" be OK without risk of rubbing on sector gear itself

BUT each build is always a tiny bit different and should be checked when fitting

(check lugs & check sector rubbing on sensor)

 

Apart from a couple of things to check - it should be moderately straight forward

 

One other minor issue you might get if the trigger pull goes too far

in some cases the trigger trips the trigger sensor, but travels a whisker further that

it clears it the other side of sensor and thinks trigger is at rest when it is at full pull

this won't be a real issue in mild guns but in much faster guns it will confuse the Perun

So in those guns close attention to the trigger & its complete start/finish points

plus adjust the rest/travel limits on fancy fucking expensive speedy trigger bollox like Maxx etc...

 

In other words - chuck your red trigger in - should be alright

but if it acts weird investigate tigger or try old one to see which one is better

as said - on a reg gun this trigger travel/sensor issue probably won't present itself

 

but if does see here...

 

 

 

or a mild trigger mod with some Blue Peter sticky back plastic, washing-up bottle, toilet roll will sort it I guess

 

but just a few things to look out for when installing the Perun

though being smaller than others like Titan, ASTER, T238 etc...

and the box not ultra re-enforced  with extra big massive lugs/material everywhere

it "should" offer less potential issues when installing and pre-wired ready to go almost

 

The wire it comes with is 1.0mm Cross Section Area - which is actually 17awg than 16awg

but same if not better than many guns that come with thinner 18awg

 

NB: I do not work for Perun, nor get commission either

but give credit where credit is due they done some good cost effective innovations

 

from starting out knocking out the basic Perun

which was based upon the Firestorm mosfet which in turn was based upon the Extreme-Fire SW-Lynx

(so basically they was all using the Nexperia PSMN1R0-30YLC115)

and somebody in US is still knocking out a similar looking Lynx thingy today...

 

Anyway - they knocked out the Perun basic but soon turned their attention to other stuff

and especially on the poxy G&G ETU - they created a direct replacement for ETU owners

(this alone deserves a big thanks)

then they created a smaller simplified optical that in theory is a more easier install than others

 

So yeah, not working for Perun, not on commission - just giving credit where credit is due

(and still not a big fan of fancy bollox mosfets, but if they're your thing then Perun is worth a look)

[Misery]

all in and now back together working a charm

commened at same time poretty much no modding was necaserry i did have to reshim and ad an extra shim to the bottom of the sector as it was touching the sensor

 

only issue i have ran into is my mech safety with the new trigger the cut out where it latchs is deeper than the standard m4 one so the safety slips but tbh not to fussed on that one i can live with that lol

[RonLancs]

4 minutes ago, miserydrift said:

all in and now back together working a charm

I'd like to see the results as this is what I'm doing to my MP5 - £60 for the Perun is a steal imo.

[Misery]

i was replacing the standard cyma mosfet as it had burnt out on me bud fps is still same havent tried rps as ive set full auto to 3 round burst for now

[Sitting Duck]

Now the "fun" begins with learning the programming of it all

bit of a MENSA test getting ya round it at first

but you suss it - or there's always the reset/default option to fall back on

for when you totally screw up the settings

 

lmk when you get it play House of the Rising Sun

 

semi + 3 rnd burst

or

precocking tweaking

or

binary trigger bollox

 

reckon is what many fuck about with

but hopefully you sorted it all with some fancy features (and deans pre-fitted)

 

The safety issue might be the arm a tiny smidge too big/tight

that it catches and fails to rise 101% to fully engage & stop the trigger moving

might just require a light file/sanding of the arm/leg of safety to allow it slip into position

(had a similar thing with a SHS flat trigger, just a smidge tight fit/compatibility)

 

I mean the arm might not be rising or compatible with trigger

but not got it front of me but reckon it might be the safety arm & red trigger

might just be a little too snug that the arm is impeded at last bit that it slips under trigger

 

no biggy for you atm you might think

BUT IT WILL BE if you go to a site and the SAFETY does not function correctly

yeah you can programme it auto-semi-auto-semi etc...

but at some point you MUST sort that safety out

 

Don't matter if you know about it

others may not (like your own kids)

and things being what they are...

 

a non-working saftey - don't pull the trigger coz safe doesn't work...

yeah that won't work

 

it is like like a sign that says WET PAINT - don't touch

 

EVERYBODY tests it - YUP still wet paint

(it's dumb arse human nature to touch wet paint)

 

have a tinker but look to resolve that safety asap

[Misery]

Hahaha once i had calibrated it house of the rising sun was first thing i did looool

 

pre cocking and 3 round burst set triggers set as responsive as i like and thats it left as is