ICS m4 Problem: Full Auto only, busting teeth on piston

[zener]

Hey,

I am in need of some help in diagnosing my gun problems. I have little experience with AEGs or upgrades. Any help is greatly appreciated!


Here is the background:

-ICS M4A1-
Purchased used with upgraded spring(170%), systema bushings, high torque gears, upgraded wire installed by previous owner.

Fielded it for about 20mins before the piston had the first couple teeth break off.

Bought the ICS ma-56 upgrade kit for the upper gearbox half. Installed it but used a Systema m120 spring instead of the ICS upgraded spring included in the kit. Fired it and only fired in auto, regardless if semi or auto was selected. The gun seemed to misfire on a few shots and I even had a few bb's roll out the barrel. It also seemed to lack power. I continued firing it to try to figure out the full auto problem and then heard the gear box spin and heard gear ginding. I opened up the gun and found the teeth were being ground off the piston. I'm quite frusterated with the problems and the money I keep spending on this gun that I have yet to play with in a game.

Any suggestions or ideas I would greatly apprecaite as I plan to sell this gun once it is fixed and I don't want to pass on any problems to the next owner of this gun.

Thanks in advance,
Joel

[mcguyver]

Remove your M120 spring and install an M100-level spring. I too have had this problem when using both Systema and stock aluminum pistons with this spring load in this gun. You can try a different piston, but 400+ fps with an ICS split gearbox is asking alot.

Also, ICS uses a ratio slightly faster than Marui in their gears and ICS geaboxes were designed to use ICS gears and ICS pistons. Mixing and matching parts can lead you have poor gear tooth engagement between gears and also between sector gear and piston. This poor engagement, coupled with a heavy spring load, is what caused this problem for you.

There is no quick and easy fix, unless you return it completely to stock form. If you leave it as it is, you will to do "trial and error" to find out what works for you.

It's like saying "I'm building a car using Ford, GM and Chrysler parts. What will work and what won't?" You just have to try it and see.

[littlerobz]

If you're building a car using Ford, GM and Chrysler, don't you end up with a Amc. We all know what happened to them.

[zener]

Thanks for the advice... i figured I'd have to return the gun to a relatively stock form. You wouldn't happen to know if the spring that came with the MA-56 kit would be a m100 level spring?(*edit* the spring is a m120 in the kit) The whole upper half of the gear box is all ICS upgrades because of this kit. Also, since the ICS aluminum piston is now stripped, I have at my disposal a Guarder Polycarbonate piston(Full tooth). Can I use this? Or should I look for another ICS aluminum piston?

ICS MA-56 kit:
http://www.icsbb.com/order/e_detail....&ProductID=644

Also:
I'm still seeking a solution for why my gun will only fire in full auto regardless of the selector position. Any input would be greatly appreciated.

[RecceGod]

You might be missing the little spring just on top of the selector plate

Like the one in this picture:



Without that spring, your selector plate will make your rifle fire full auto regardless of the selector switch position, because that spring make the semi/auto latch (for a lack of proper name) move to semi-automatique in the mechbox (someone else might be able to explain that mechanisme better than me).

Anyways, a spring from a bic lighter, or from an old hop-up, cut to proper lenght will do the trick.

[zener]

Ok thanks! I will look into that.

[RecceGod]

so did you figure out the auto-only fire problem yet?

[zener]

I haven't been able to take out the lower gear box, I'm not too sure about how to do it.

[Death March]

Did you take out the Mag. release and the very small pin above the trigger,I'm guessing you'v taken out the pistol grip and motor first! Hope that helps!