ICS L85a2 overhaul

Customers high mileage SA80 in for a well deserved birthday!

This L85 has done its fair share of work having put down 10s of thousands of BB’s and it was showing.

Reported faults were:

  • Poor trigger response
  • Feeding issues
  • Semi / auto fire problem
  • Low FPS

Aside from investigating and repairing the aforementioned faults, an upgrade in consistency and accuracy were requested, (and as this RIF is a long term-er, the internals are to be upgraded for endurance and reliability). So on with the overhaul!

As with pretty much all our work we begin with a baseline and functionality test so we can reference performance and experience any outlined faults.



Bearing in mind a UK spec ICS L85 is built with an M100 main spring and 3 position adjustable power spring guide, on maximum power setting we can see this is way down on performance as the customer noted. We should be seeing in the region of 345 FPS!

So we can see we have major air seal issues or a fatigued main spring, in this instance i’d expect both.

Although these particular guns do not fire very fast the ROF is clearly lacking and as reported the trigger response is lacking for sure!

With regard to the feeding issue initially we could not get this fault to rear its head – despite testing on our own good mags and the customers – however double feeding was noted on semi, a classic ICS L85 trait that is easily rectified.

AEG STORAGE TIP: Always fire the gun in semi before leaving the gun for any period of time so that the main spring can uncompress / relax, reducing the onset of fatigue. Likewise, if you have a gun capable of PRE-COCKING make sure to fire it in normal semi mode before leaving it.

Next up we pulled the upper receiver to remove and inspect the hop unit assembly…

hop fail 2


Oh! Well that was not expected! At some point in the past someone, somehow has managed to break the whole hop unit in half!! Clearly not going to help our air seal or feeding issues, amazingly this gun still shot ok considering this major failure!


Moving on, here you can see the proprietary ICS L85 gearbox housing, although most internal parts are V2.

You can also see the ICS 3 position power spring guide and QR pin.

cutoff mech

Looking into the lower receiver we can see a heavily worn semi cut-off relay lever shining away! This is our semi / auto fault. This will need to be renewed.

In the foreground you can see a little marring on the relay plate caused by lots of receiver removal and refitting, this will have a negligible effect on the semi fire system.


Pulling the motor, the pinion looks impeccable!


After stripping the motor the guns high mileage is clear, the motor brushes and commutator are heavily worn, and some not so pretty terminal soldering, all adding to our trigger response and ROF reduction.

The ICS Turbo 3000 is great motor, designed to pull much more powerful springs as standard, this one has had its day though.


Stripping the gearbox down we find a tiny piece of swarf, this is a gearbox shell casting imperfection, luckily held out of the way of the spinning gears by grease.


Now this is another great part about a lot of ICS guns that do not get commended enough, ICS gears are seriously hard and well made, if you are looking for a good set of gears for a build and are happy with a normal gear ratio (18.75:1) this are a great option.

The gear axles also measure up precisely with perfectly round shafts exactly 3mm in diameter. These gears are keepers for sure and will give a super smooth and quiet gearbox.


Having spun so many thousands of cycles this particular gear set is honed to perfection, you would struggle to find a set of ‘upgrade’ gears that could equal these. The bushings however are rather worn and will require renewing.


Zero wear to the most highly stressed tooth in an AEG gearbox! Compare them to the likes of a TM Recoil standard gear set and there is no contest!

Watch this space for the rebuild updates!

4 thoughts on “ICS L85a2 overhaul

  1. For the ICS L85 how did you solve the Semi Auto issue where it double fires then stops firing. Full auto works fine and switching to full auto corrects the issue until you go back into semi auto and it’s ok for a few shots then starts double firing again.


    1. Hi Andy,

      Double firing or fire selection issues are down to worn fire selector levers and/or semi cut off lever.

      Double feeding on the ICS L85 is caused by the nozzle being too short, this allows more than one BB to be loaded every now and then.
      We machine a nozzle especially for the L85.



  2. Do you guys machine the semi cut-off relay lever yourselves? I think I may need a replacement as the semi/auto problem on my gun is making me want to drive over the damn thing with the car. It’s the last thing that I havent replaced yet. Gun just randomly stops firing or will only fire in semi or just for giggles will sometimes switch to full auto.


    1. Hello, We do not, however the part is available directly from ICS.
      Regards, Dave@SixG


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