Cybergun F2000 (Cyma) - Internal upgrades / tinkering

[RostokMcSpoons]

My Tactical Tuna is a big ol' hunk of loveliness, but mechanically I can already see and feel first-hand the failings compared to the much more refined build of my Double Eagle M906C.

The highest muzzle velocity I've seen from it with no hop at all is 270fps so it definitely needs more oomph.

I've got a few quid I can spare to make it better, so I'm likely to use @Asomodai's shopping list of parts in his recently sold gun as the basis for my long-term build.

• G&G metal Hop up unit  
  

• AOLS 380mm Barrel 
  

• Maple Leaf 50 Degree bucking, Ohm nub  
  

• Mosfet
  

• SHS High Torque 22TPA Motor
  
• Short stroked
  

(Asomodai, would you pick the same components again if you were re-building the gun?  Any parts you'd substitute with the benefit of experience?

Which Mosfet did you go with?)
So I'm immediately pulling it apart to see everything is as best as can be, with a view to swapping the hop bucking and nub and the main spring as the first steps in the journey.

I'm a little bit stymied by the fact almost all the F2000 videos out there relate to the G&G version, not the Cyma one.

I'm trying to be gentle with things because I'm still inexperienced and don't want to break stuff, but I've already found when trying to fiddle the backplate out that some effort, twisting and bending can be needed to make things happen.

I can now see the gearbox in all its glory, but it doesn't want to shift at all.  I can see the motor height adjustment screw at the bottom but that seems to be just sitting in place, not holding in. 
I've taken out the two cross bolts from the stock as well, though I don't if they're involved.

Pressing backwards on the gearbox above the nozzle from the 'flip top bin'  sees a couple of mm of rearward movement, but that's it.

Is there a trick to removing the gearbox from the body?

Once the gearbox is out, I just want to put a stronger spring in.   I've got a spare M100 spring, and also a couple of springs that were inside the box (but they're linear and shiny and look a bit cheap so probably won't try them after all)
If I crack open a v3 gearbox, managing to hold the main spring in place, will anything else shift out of whack?  Will I have trigger springs pinging around etc?  Basically I'm asking:
Can an idiot (me) replace the mainspring in the gearbox and put it back together easily?

 

[Adolf Hamster]

The highest muzzle velocity I've seen from it with no hop at all is 270fps so it definitely needs more oomph.

might want to try with hop on, whilst it's counterintuitive sometimes having the hop completely off will reduce the muzzle velocity.

Once the gearbox is out, I just want to put a stronger spring in.   I've got a spare M100 spring, and also a couple of springs that were inside the box (but they're linear and shiny and look a bit cheap so probably won't try them after all)
If I crack open a v3 gearbox, managing to hold the main spring in place, will anything else shift out of whack?  Will I have trigger springs pinging around etc?  Basically I'm asking:
Can an idiot (me) replace the mainspring in the gearbox and put it back together easily?

the answer is it's hard to say.

some v3 boxes the triggers will behave and sit in position as long as you don't mess with them, others they'll make a bid for freedom immediately. they can be a bit of a bear to get back in but for an unworn box they should at least stay put once you have them back in position.

things like shims it's very common for them to stick to either the bearing, the gear, or both (eg one shim goes one way the other stays where it is), although as long as you keep track of where they were originally it's not a problem (unless you're going to do a full reshim in which case it's irrelevant)

tappet plate may play nice, or not depending on where it is in the cycle when you open it. however when reassembling it'll sit nice as long as you have the sector gear in the right orientation so it isn't pulling the plate back.

anti reversal latch will generally be annoying, a good method is to use a magnet on the underside of the box to hold it in place on reassembly. you can also sometimes get it to sit by putting backwards tension on it via the bevel.

 

[RostokMcSpoons]

Thanks @Adolf Hamster I think the takeaway message from that comprehensive answer is "no, not if you have no feckin' idea what you're doing (I can see you googling which one is the bevel right now), you clown" 

But... I've got to learn this stuff sometime.

I've got some little neodymium magnets I can use for the latch - that's a good hint

How do I shift the gearbox though?  Is it just requiring a bit of brute force to get it out of there?

The fps went as low as 200fps with (presumably masses of) hop on but I will try adding hop in smaller increments, just to see what I'm working with.  I presume you're talking about 'joule creep' where a a slower initial velocity leads to more time for the air pressure to build, and a higher final velocity?  

 

[Adolf Hamster]

Afraid i cant help with getting the box out, the g&g version there was a metal frame in the body it slid into, which was very stiff when the gun was new.

But as you know the cyma version is an entirely different setup so might not work that way. Maybe split the bodyshell see if that shows how its meant to go together?

Wouldnt worry about being inexperienced, we all had to start somewhere, ironically starting with the g&g with its v6 box i didnt know how spoiled i was with its modular dissassembly (by the time you split the casing theres only really the tapper plate left) until i got an m4 and realised how much of a pita it normally is

 

[RostokMcSpoons]

Cheers again.  I was searching for hints about f2000 disassembly and over of the posts was "what's the worst gun you have worked on" and one of the replies was "Cyma F2000, when I split the body to take out the gearbox and the trigger assembly was a nightmare to get back together"

So I'll try to avoid that ?

 

[Adolf Hamster]

ahh yes, a fair point the trigger probably is a bit more complex than the g&g's simple push rod.

 

[RostokMcSpoons]

Edit:  I got the gearbox out by removing all the bolts towards the rear of the stock and prising the stock open a little, and eventually it dropped out (with me pushing on it).  I think the bolt directly above the word 'f2000' stops it moving, that's the key one. 

Well I've split open the gearbox, and I think I've managed to keep track of all the shims and I can refit the reversal latch and all that other crap.

But the trigger spring is giving me the absolute arsehole.

View attachment 83069

the arrowed bit of plastic gets in the way, so I can't hook the spring around the back of the trigger block AND drop it into place, without the gearbox hook coming out.  If that plastic block wasn't there it'd be easy but the tappet mechanism needs it.

How do I reinstall this trigger? Any handy hints???

It's piss-easy on a normal v3 gearbox, judging by this excellent video:

Pertinent bit is at 19:47

Edit: I ended up super-gluing the geabox end of the spring into the gearbox.  That meant I could wedge the trigger from an angle in without it popping out altogether.

To ensure the pin locates into the hole properly the spring needs pushing 'up' the pin.  The damned thing is stepped so it tends to stick where it's not wanted ?

OK, I had to give in and take apart the tappet plate etc.  The trigger is now in place, I just have to hope everything else will fit together on top

Now I've got the cylinder out, I've tried compressing it with my thumb over the nozzle.  There's very little resistance, so my air seal appears to be awful.  Maybe by design?

The cylinder head appears to be ported... my technical knowledge has run out at this point, I thought more pressure = more pew pew power.

 

[RostokMcSpoons]

I'm sure everyone else has had this problem when putting gearboxes back together, it's possible to get everything in place but not all at the same time.

Compressing the main spring and holding that in place whilst trying to get everything else to line up ... arrrrggghh

And I've only managed to get the trigger spring in place a couple of times but the pins are so out-of-alignment the shell will never get close to getting together

How do you guys do this???

 

[Adolf Hamster]

How do I reinstall this trigger? Any handy hints???

not really, the method shown in the video is pretty much the right method, although i suspect there's heavy magic of editing that's primarily responsible for making it look so slick.

it's really hard to describe the movements, but you first hook the loop of the spring with the trigger, then go for getting that end of the trigger into the hole on the casing, then worry about angling the transfer peice into it's respective hole.

How do you guys do this???

magnets and a lot of swearing.

as long as the pins remain seated in the lower half, when closing the shell together you can apply light pressure then proceed to wiggle/poke the various ends into their respective holes.

 

[RostokMcSpoons]

I'm 4.5 hours in and still can't get it back together.  Is that par for the course or am I irredeemably ill-suited to this bedroom-teching lark?  

 

[Adolf Hamster]

I'm 4.5 hours in and still can't get it back together.  Is that par for the course or am I irredeemably ill-suited to this bedroom-teching lark?  

it always takes longer until you build up the experience of how things go apart/come together, how much pressure to place/not place, what angle to use etc etc, sadly so much of it can't easily be explained through writing and just needs many attempts to establish the "feel" required.

even when you've got a good handle on things it can still take hours to do a build properly (and that's if the build is well behaved and doesn't throw up weird issues)

what specific bit are you stuck on?

 

[RostokMcSpoons]

I went off, had a bite and a beer and came back to it.  Decided to build a jig to hold things (especially the trigger) in place as I'm closing the shell...

"Ta-da"
View attachment 83072

Yup, just a block of wood with some appropriately placed nails...

Worked a treat, put the shell back on and wiggled things into place on my second attempt!

Connected up to the motor, bound up on the first shot.   I didn't check the gear positions before I closed it (bound to miss something).
Problem is, when I opened it up again, with the spring half-cocked, the spring released and *something* went flying over my shoulder, probably lost for a month or two.

I think it's just one of the shims.  All the springs are present and correct.  

 

[RostokMcSpoons]

Blimey.   Still not got it back together. 

Made one change to the jig - drilled a hole under the anti-rev latch's position, stuffed a couple of neo magnets in there, stacked a couple more on top - latch held in place

View attachment 83073

My main spring finds new and exciting ways to escape before everything lines up.  I know it's just a matter of strong fingers in the right places, plus perhaps a little bit of luck, but it's not happening.  Even if I keep the spring inside the shell, if it 'jumps' then it dislodges the bracket the trigger contact slider sits in, and I have to remove the tappet plate to reposition it.  Arrggggh.

But anyway... I've rehearsed lining up the shell without the main spring.  I can get all the pins to locate and the shell to snap shut nicely.

The problem is the gears are wobbling around.   I don't think it's the fact I've probably lost 2 or 3 shims with the the spring flying about, the sector is moving perhaps a full 1mm sideways.  Perhaps that thing that flew by my ear was important after all

I certainly can't put it back together without a bunch of shims at least, and I don't have any.  Can I get them from Screwfix?

edit: looks like screwfix is a 'no'. 
Looks like I'll be making an order before I can continue.  Might as well get some proper parts too!

 

[Adolf Hamster]

oh dear.....

to start off with the main spring- you can shove a screwdriver (or similarly sized pokey thing) through the back of the spring guide and use that to help hold it in position. some v3 casings might not have a hole in the back of them to accomodate (usually for v2 boxes they do as that's a stock attachment point) but you can file a hole in the casing.

usually, if you seat the spring guide nicely then hold pressure on the cylinder it shouldn't jump out too far- you can see the way he has his fingers through the window on the upper half when placing it in position.

the sector moving side to side defo sounds like you've lost a few shims. i'd say get a pack of @ak2m4's 0.1mm shims as they always come in handy: https://www.ak2m4.co.uk/internal-parts/bushings-shims/xt-shims-01mm-100-pack

you can also get clips that help hold things into place, never used them myself but mostly because i've never got around to getting any: https://www.ak2m4.co.uk/gearbox-helping-hands-kit

 

[RostokMcSpoons]

Cheers, I definitely need a big bag of shims.  My jig is actually doing a pretty good job for me so the helping hands clips aren't necessary.

While the thing is in bits though, it seems sensible to upgrade any more parts at the same time.  

The cylinder and piston seen to be prime candidates, anything special I need to look for?

I saw this

https://www.patrolbase.co.uk/master-mods-full-steel-teeth-reinforced-upgrade-piston-set

It's out of stock but is that a sensible upgrade?

 

[Adolf Hamster]

kinda depends on your goals as to what parts you might want to change out.

certainly for outdoor use i'd be thinking about air seal related components, particularly the nozzle, cylinder head & piston head.

piston teeth is one that's debatable, there are good arguments for having plastic teeth as a failure point and steel racks aren't immune from failure (having the racks ripped out of them assuming the gears don't eat themselves first).

that port cut is confusing me, looks kinda far for the barrel length of an f2000. where's @Sitting Duck when you need him he's better at this than me

 

[Asomodai]

My Tactical Tuna is a big ol' hunk of loveliness, but mechanically I can already see and feel first-hand the failings compared to the much more refined build of my Double Eagle M906C.

The highest muzzle velocity I've seen from it with no hop at all is 270fps so it definitely needs more oomph.

I've got a few quid I can spare to make it better, so I'm likely to use @Asomodai's shopping list of parts in his recently sold gun as the basis for my long-term build.

• G&G metal Hop up unit  
  

• AOLS 380mm Barrel 
  

• Maple Leaf 50 Degree bucking, Ohm nub  
  

• Mosfet
  

• SHS High Torque 22TPA Motor
  
• Short stroked
  

(Asomodai, would you pick the same components again if you were re-building the gun?  Any parts you'd substitute with the benefit of experience?

Which Mosfet did you go with?)

A tech went with an insane short stroke. But only because decent 13:1 gearsets were non existent at the time. 

I would never short stroke again because the 420mm barrel length is already at the maximum for the air volume of a full type cylinder. 

You need to replace the Cylinder to a full type as you are already losing alot of volume with the port. The less volume, the more unstable heavier bb's will be. 

I just used a basic mosfet to protect the trigger contacts. 

As for a motor/gear combo. 

Best would be 22TPA Neo motor and 13:1 gear ratio. 

Good would be 16TPA Neo Motor and 16:1 gear ratio. (Just as fast as the above option, but would drain battery quicker). 

 

[RostokMcSpoons]

@Asomodai thanks for that useful info!

I'm looking at 15-20rps as my target.

Current motor has 10 teeth

Bevel gear has 30 teeth

Spur gear has 39 teeth

Sector gear has 30 teeth

If I've counted correctly and used this: http://airsofttech.dk/Calculator.cshtml correctly, that is 17.55:1  
(If the spur has 40 that would make it a round 18:1 ratio, so it seems likely I miscounted there!)
 

So looking at your recommendations I'd need quite a high speed motor to turn those rapidly, with commensurate high battery drain, and perhaps a a higher wear rate... those don't worry me toooooo much... 

I just watched the Airsoft Tech explain about volume ratios... https://www.youtube.com/watch?v=LT0ptGQMc5g&t=628&ab_channel=TheAirsoftTech

The preferred cylinder to barrel ratio for my preferred 0.28g BB's should be 1.5-1.8, according to him.

I measured the internal length of the cylinder from port to back of the cylinder head as 22.3mm, with a cylinder radius of 11.7mm giving a total

cylinder volume of 9,590mm3

With the barrel length as 420mm with an internal radius of 3mm giving a total

barrel volume of 11,875mm3

That gives a cylinder / barrel ratio of 

0.8075

Oh dear...?

I'm off to look for a possible set of parts.

 

[Asomodai]

@Asomodai thanks for that useful info!

I'm looking at 15-20rps as my target.

Current motor has 10 teeth

Bevel gear has 30 teeth

Spur gear has 39 teeth

Sector gear has 30 teeth

If I've counted correctly and used this: http://airsofttech.dk/Calculator.cshtml correctly, that is 17.55:1  
(If the spur has 40 that would make it a round 18:1 ratio, so it seems likely I miscounted there!)
 

So looking at your recommendations I'd need quite a high speed motor to turn those rapidly, with commensurate high battery drain, and perhaps a a higher wear rate... those don't worry me toooooo much... 

I just watched the Airsoft Tech explain about volume ratios... https://www.youtube.com/watch?v=LT0ptGQMc5g&t=628&ab_channel=TheAirsoftTech

The preferred cylinder to barrel ratio for my preferred 0.28g BB's should be 1.5-1.8, according to him.

I measured the internal length of the cylinder from port to back of the cylinder head as 22.3mm, with a cylinder radius of 11.7mm giving a total

cylinder volume of 9,590mm3

With the barrel length as 420mm with an internal radius of 3mm giving a total

barrel volume of 11,875mm3

That gives a cylinder / barrel ratio of 

0.8075

Oh dear...?

I'm off to look for a possible set of parts.

You're over thinking it. 

Don't worry about the volume calculator, the cylinder types/volume matching for AEGs are well known. The calculator is more for oddball setups and sniper rifles, just get a full non windowed cylinder. 

The teeth on your gears and motors are all standard as it's a standard AEG so don't worry about counting them. If you do replace the piston I recommend going with a 14 1/2 tooth or a 14 tooth piston instead of a 15 tooth for better AOE. 

High speed motors also create alot of heat. Almost no one goes for high speed motors anymore because of the downsides, they only exist because high speed gears didn't exist a decade or so ago. And it was the easiest way to gain lots of RPS.

We now have high speed gears and high torque motors readily available which when combined give better performance, better efficiency and lower heat. 

If your aim is the lowly RPS you mentioned and you want to keep the stock gears just get a 16tpa neo motor. Which gives a reasonable bump in trigger response and RPS without having to replace the gear ratio.

 

[RostokMcSpoons]

Me, over-thinking things?  Shurely shome mishtake 

Thank you so much for that. I'll amend my shopping list accordingly... back with that shortly.