ICS Woes
 

Alright boys, my ICS needs some diagnostics done on 'er.

Gun History:
Purchased second-hand from a reputable member on ASC in January 2008, its FPS was 290 which was weird as he had upgraded the internals. Have not had it touched until TAC09 when the spring was replaced by a gun doc with the (supposedly) same strength spring (Modify S100), I was told that the spring might have been too used/broken down to sustain FPS. With the new Modify spring the FPS dropped to 280, again I was puzzled. New spring has seen less than 1000 Rounds since then.

I changed out the stock Piston/Piston head for a Mad Bull Piston with full teeth and a Modify bearing piston head. The gun now chronies from 250 to 320 using BB Bastard .20's with the hop up completely off and a fully charged battery.


Barrel: Madbull Black Python Tightbore 6.03mm
Gears: Stock ICS (Metal)
Spring: Modify S100 (should be at 370fps)
Spring Guide: Unknown V2 with bearings, probably systema
Piston: Modify Polycarb Full teeth.
Piston Head: Modify Polycarbonate Bearing Piston Head
Tappet: Stock ICS
Battery: G&P CRANE 9.6V 2200 mAh
Bushings: Stock ICS
Shims: Systema Shims
Cylinder: Stock ICS
Cylinder Head: Stock ICS
Nozzle: Stock (I assume)
Hop Up Unit/Sleeve/Bucking: Stock ICS

Any Ideas WTF is wrong with it? its become a real pain and I swear it is cursed.

air seal problem which is air nozzle/hop up/bucking related...change one or all

I second rusty sniper's opinion. This is definitely an airseal problem.

Sometimes if there is a bad airseal, the gun will shoot at the same FPS no matter what spring you put in(Unless its weaker than the FPS.) For example, one of my guns used to shoot 330FPS no matter what I did(M120, M110, M140) until I fixed the airseal.

So check the hop up rubber to air nozzle area, that's usually the area.

Hope that helps

Suggestions for a temp fix just to see if that IS the problem? (im thinking teflon tape)

Not sure where you would tape the teflon tape. It's just that everytime I've had the same problem it was because of airseal between the hop up rubber and airseal nozzle. Try reinstalling your barrel a few times.

It's best to use an ICS nozzle with an ICS hop-up. The stock ICS one is a tad longer than Marui-spec.

Cylinder is installed with the vent holes at the rear?

Yes.
Would photos of certain areas help?

It might but vent holes facing the wrong way would give much lower FPS readings I think. The vent in your cylinder needs to be at the BACK (further away from the nozzle). If it's facing the wrong way most of the air just escapes. Did you do a compression test when putting it all together? I suspect maybe the piston head is not sealing with the cylinder.

as I said, the cylinder holes are at the back

since the piston head and the cylinder are diff brands, make sure they have good seal against eachother. same goes for the seal between the cylinder head and cylinder, and cylinder head and nozzle.

try using a slightly longer air seal nozzle. not sure which gun uses slightly longer one than sotck ICS though =\

the Guarder airseal nozzle is longer just by a fraction. im using it and seems to be alright. i did a lot of research before getting the guarder airseal nozzle in my ics m4 and actually many people are using it in their ics m4 guns.
the ehobbyasia link: http://shop.ehobbyasia.com/guarder-a...m16a2-aeg.html

Suggestions where to source a new hop unit? ive tried RW and WGC with no results.

I'm probably going to need one as mines got a huge crack in it, so if you find one lemme know or post it here, because I gotta grab one too!

www.blazingtoys.com

ICS parts dealer in the US that will
ship to Canada. My main source in
the past for building ICS M4's.

Edit: Just give your gun to Tyson
(m102404), he'll fix her right up.

PM Shinobii. He's either got one in stock or can get one or (if you're really nice and a contributing member of society) he might pull one out of a stock gun in a pinch).

The last one I needed, I picked up...but I'm sure he prefers shipping them out for most cases.

He's bringing in a bunch of complete upper mechboxes as well...so that's a nice option to have in a pinch.

If the nozzle/cylinder head airseal is good...then it could well be the nozzle-rubber fit.

With the rifle fully assembled, I'd do the following in this order (least work to most involved):
1. Pull the barrel, reseat the existing hopup rubber. Reassemble and test.
2. Swap the hopup rubber, reassemble and test
3. Check the piston o-ring/cylinder compression, test
4. Swap upper into another rifle that's working reliably

Best of luck,

Tys

I also dont have the front mounted spring on the hop up (but I found a replacement), i hear varying opinions that it matters and that it doesnt, any confirmations?

pushes hop-up unit into the mechbox, provides better air seal. It matters. Or else the only thing holding it in place would be the mag.
Cut a few coils off of a spring-loaded pen... spring

The spring is pretty important. You can tell if that is affecting performance by manually pushing the hop up against the upper, if it fires better then that could be part of it.

How long should the spring be? I took one out of a pen but it keeps bending away whenever I put the hop unit back in.

It doesn't matter how long it is, but more or less how straight and wide it is. It should fit snugly on the hop up and point straight and not bend down.

Have added spring to hop unit, Chronied at a game to 335 FPS steadily.
Later I chronied it again, with the hop up on (shoulda turned it back off) 277FPS, but I believe the chrono may have died as I fired repeatedly but didnt get a refresh (and yes BBs were firing). I even turned it on and off and didnt get a number at all after.