CYMA - firing hot!

everlast75

Hi there,

I ordered over the internet and am now in the possession of a CYMA Mp5K.

The readings provided with it state that with a .2 g bb, its firing just over the legal limit (circa 340 fps).

I understand that this can be sorted by the fitting of a spring, but can anyone provide more info please? If I can do the job myself, I'd rather. If not, I'll drop it in and have it done professionally.

Thanks

SentinelStance

Take the gearbox apart, fit a €10 M90 spring, maybe shim it while your in there. Job done. If you never took a gearbox apart before dive right in! Do not worry it will all go back together!

sci-ops

Spring Upgrade version 2 gearabox - http://www.youtube.com/watch?v=TqEUdrWElEY

If your not sure how to disassemble your MP5, just google. It's a pretty easy job.

Get yourself an MS90 spring and your good to go.

Good luck.

Untamedlemon

everlast75 wrote: »

Hi there,

I ordered over the internet and am now in the possession of a CYMA Mp5K.

The readings provided with it state that with a .2 g bb, its firing just over the legal limit (circa 340 fps).

I understand that this can be sorted by the fitting of a spring, but can anyone provide more info please? If I can do the job myself, I'd rather. If not, I'll drop it in and have it done professionally.

Thanks

Does it say this reading on the box or on a chrono sheet? Where did you buy it? If it says 340 on the box and Bought it in Ireland I wouldn't worrY about it as guns are usually made in places where 340 is allowed and retailers here tHen downgrade them. If it is actually shooting 340 and you bought Irish then ring the retailer and they should do the downgrade for free.

everlast75

Untamedlemon wrote: »

Does it say this reading on the box or on a chrono sheet? Where did you buy it? If it says 340 on the box and Bought it in Ireland I wouldn't worrY about it as guns are usually made in places where 340 is allowed and retailers here tHen downgrade them. If it is actually shooting 340 and you bought Irish then ring the retailer and they should do the downgrade for free.

Thanks a mill
I ordered it over the internet.
It had those readings on the sheet, handwritten (albeit in Polish!)


Any chance anyone could point me where I could pick up that spring? Pop into any retailer?

thermo

most retailers would carry a decent selection of springs and other internal parts. make sure you bring the gun with you and have it chrono'd to confirm muzzle energy before any work is done.

DeBurca

The MP5k use a version 3 gearbox and not a veraion 2 as found in the MP5 range of AEGs

Inari

Changing a spring on a gun is very simple; it's just nerve-wrecking for the first time.

All you have to do is make sure you have a decent amount of time where you can be uninterrupted, have a clean flat work space, and suitable tools. To take apart the gun:
- Remove the stock/end plate by tapping out the two pins
- Remove the handguard pin, and take the handguard off
- Tap out the pin at the magazine catch
- Slide the upper receiver off of the lower
- Remove the motor base plate, disconnect the motor & remove from receiver
- Undo the two screws inside the pistol grip; the gearbox should now lift free

Clear the work space, make sure that you keep track of where everything goes! For opening the gearbox you will need a thin screwdriver or allen key to insert into the spring guide (to avoid it flinging off into the distance).
- Undo all of the screws on the gearbox, and hold down the top half of the shell with your hand.
- Open the shell slightly at the back, and stick in the screwdriver into the spring guide, and apply downward pressure.
- Use a small allen key or screwdriver to push the axles of the gears out of the bearings/bushings)
- Open the casing more at the back and remove spring guide (and spring), and remove top casing
- Make sure everything is in it's proper place, and put in new spring reversing the process!

everlast75

Inari wrote: »

Changing a spring on a gun is very simple; it's just nerve-wrecking for the first time.

All you have to do is make sure you have a decent amount of time where you can be uninterrupted, have a clean flat work space, and suitable tools. To take apart the gun:
- Remove the stock/end plate by tapping out the two pins
- Remove the handguard pin, and take the handguard off
- Tap out the pin at the magazine catch
- Slide the upper receiver off of the lower
- Remove the motor base plate, disconnect the motor & remove from receiver
- Undo the two screws inside the pistol grip; the gearbox should now lift free

All done to that part, but the gearbox won't lift free as there is a wire that runs from just above and in front of the trigger mechanism to the front end of the barrell, at the Tamiya connector

I've tested its connection and it doesn't slip off the copper connector

King John The Last

You have to take out the barrel as well to get it out, that's how I do it anyway. There is a screw on the right side just inside the foregrip, take it out and then try to pull the gearbox out again carefully. The barrel and hop up should come out the back with it. Tell me if you can't get it and i'll add pics.

everlast75

King John The Last wrote: »

You have to take out the barrel as well to get it out, that's how I do it anyway. There is a screw on the right side just inside the foregrip, take it out and then try to pull the gearbox out again carefully. The barrel and hop up should come out the back with it. Tell me if you can't get it and i'll add pics.

Will try that tomorrow. I've a funny feeling I'll be putting the pieces into a bag and heading down to a professional ha ha

everlast75

King John The Last wrote: »

You have to take out the barrel as well to get it out, that's how I do it anyway. There is a screw on the right side just inside the foregrip, take it out and then try to pull the gearbox out again carefully. The barrel and hop up should come out the back with it. Tell me if you can't get it and i'll add pics.

Pics are unfortunately needed


Dunno if I can get it done in time for tomorrow's skirmish :-/

King John The Last

everlast75 wrote: »

Pics are unfortunately needed


Dunno if I can get it done in time for tomorrow's skirmish :-/

The screw in the picture is the one that you need to take out. Then you should be able to poke it out with a screwdriver like in the other picture. The fuse on the wiring tends to get stuck at one point. Just wiggle it around and it should go through. Make sure that you have taken out all of the body pins first though.

everlast75

King John The Last wrote: »

The screw in the picture is the one that you need to take out. Then you should be able to poke it out with a screwdriver like in the other picture. The fuse on the wiring tends to get stuck at one point. Just wiggle it around and it should go through. Make sure that you have taken out all of the body pins first though.

The black adapter is stopping the removal of the unit

King John The Last

everlast75 wrote: »

The black adapter is stopping the removal of the unit

Here is a terrible video of me doing that step with one hand. I'll put up a better one tomorrow if you still want it, all i had today was my phone.

everlast75

King John The Last wrote: »

Here is a terrible video of me doing that step with one hand. I'll put up a better one tomorrow if you still want it, all i had today was my phone.

Please - I'm one step away from bundling the parts into a plastic bag to someone who knows better

King John The Last

View My Video (hope this works)

everlast75

Thanks a mill mate - above and beyond the call of duty - appreciate it.

Now to tackle the spring.. And then reassemble :O

King John The Last

Happy to help

everlast75

I've progressed some more but am having trouble removing the casing for the gears.

There's some give at certain parts but not others.

I've attached a pic and it shows that the area around the trigger remains tight.

Any ideas?

everlast75

I've progressed some more but am having trouble removing the casing for the gears.

There's some give at certain parts but not others.

I've attached a pic and it shows that the area around the trigger remains tight.

Any ideas?

DeBurca