HELP! M4 wont cycle
 

sigh* so ive been working on this thing for the past week and cant seem to make it work. I want to have it upwards of 400 fps for outdoor games with an m120. It was a JG SIR system that came 400+ stock. I upgraded it for indoor play with
-m100
-high speed gears
-G&P m120 high speed motor
- ARS Duo Pistonhead + Cylinder head Sorbopads (it also has bearings in the piston head)
- Cylinder with no ports

now i was reupgrading it for outdoors and it wonts cycle...
yes the batteries are charged, ive tried an 8.4, a 9.6 and even a 10.4
atm i tried
- Both M120 G&P motor and Stock JG ( which pulled 400+ stock no problem)
-JG stock gears
- ARS duo sorbo set
- and an M120 spring


Ive now broken 2 pistons... lol. first one was a
-Modify High Speed Ultra Piston - New Version ( the back end Broke off)
-Stock JG piston (same thing happened)
and on both i had the ARS duo installed.

now im using another JG stock piston but ive shaved off the second tooth and 1/3 of 3rd too for clearance from sector gear. The AOE seems to be good.
Ive tried different motor heights, The gears and spur gear of the Motors are in great condition. I've shimmed it properly *imo*
it does not complete a full cycle at all...
gahhh i need help. im gonna explode :banghead:

Have you tried removing the bearing from the piston head some times when you have a bearing springguide and a bearing piston head it wont fully cycle and gets locked in the full back position. Had this happen in my CA when i threw a 120 tuneup kit in.

i didnt try removing the one from the piston but ive removed the spring guide bearings. ill try to switch it

EDIT:.... GAHHHHHHHH the motor connector broke... FUUUU rage... so i cant even test it atm. i dont have a soldering iron -_-"

what brand are your high speed gears?
Certain components are best kept within the same brand, most importantly your gears and piston.
For example, a prometheus piston is very specifically designed for, proven and tested on, prometheus gears. And I've heard of cases where they strip easily on other brands of gears.

i'm not a supreme gun do or anything, but you did mention that you are running a full cylinder in an m4.... isn't that a no no?

Hi. I have modify gears that I ran with a modify high speed piston and It broke. Also I have a 509mm inner tbb for the full cylinder.

I'm not surprised the modify piston broke. Generally speaking high speed pistons shouldn't be used in guns that shoot >350fps.

However your situation hasn't really changed. Typically I assume that 'gun won't cycle' issues are problems caused by awful batteries and/or chargers. Like people using wall chargers and vanaras branded batteries etc. I"m right with this 9/10 on the field when I plug in my battery to their gun.

The second most common issue is motor height being FAR FAR too high and binding the entire gear train. Back down the motor height to test.

When you have your GB and pistol grip on the box, and you pull the trigger do you smell and burning, hear any clicking sounds or is their just absolutely nothing? Test this by taking the motor out of the grip and pulling the trigger with the motor leads connected testing your electrical system and motor function. The box SHOULD cycle with the motor in.

If it's neither of the above, you need to re-open the box. The next thing I would hazard a guess at is without seeing it is over-shimming and awful AOE engagement as you are tearing the pickup lugs off the pistons.

Youtube AMOSV2 and find his video on proper AOE, it's a great guide for newbies.


I have never heard of being a problem. I run bearings on both spring guide and piston head in all my upgraded guns. As the spring is being compressed you want both ends of the spring to twist and turn freely. If you take a well used spring out of a AEG with just bearings on one end, you will see that it doesn't stand straight anymore and is rather crooked. If you use bearings on both ends, the spring tends to retain it's original shape far better and give you a longer and more consistent life.

No, changing the porting on your cylinders is how Marui maintains all of it's gun at ~280 FPS regardless of barrel length using the same spring. If you are shooting >400 FPS, I personally see no reason why you should just dump out the ported cylinder regardless of barrel length silly setups aside. It's how many users are able to run lower power springs to achieve 420+ velocities, thus getting them snappier trigger response, and higher RoF

i got it working -_- the m120 was too stiff. so i got a modify s110 instead and it was pretty much 40% easier to install and it cycled perfectly.

Could still be a shimming issue.

i believe hes right. I've upgraded 4 mech boxes in the last 3 days and its the shimming that fucks everything up.