Cyma Cm.621 Upgrades

[Shamal]

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]

FTFY ?

BURN THE HERETIC!

 

[Shamal]

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]

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]

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]

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

View attachment 68192

 

[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]

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

View attachment 68538

View attachment 68539

 

[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...

View attachment 68545

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...

View attachment 68546

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)