CYMA M14 EBR Jamming(?) problem.

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Little bit of a background on the Gun and the lead up to the jam.

- It has a guarder sp120 full tune up kit installed a month ago + re-lubed (version 7 gearbox)
- Was running to maximum with a stock motor and 9.6v intellect 1600mAh
- Switched to a Guarder Infinite torque up motor after a few weeks
- installed a MERF 3.2 mosfet at the same time and was fiddling around with the burst function
- Gun jammed after about 30 shots. Nothing shoots, motor doesn't spin
- Motor works perfectly when removed
- There were a few BBs in the hopup and by the nozzle
- the gear closest to the motor moves/rotates back and forth a TINY bit if you try and move it (I don't believe it ever did that before)

Any advice? I'd rather not have to open up by gearbox again, but I figure that's what it will come to. The re-enforced gears in the sp120 kit should be enough for the guarder infinite torque up motor, right?

Does anyone know what could have caused a jam like this? Could it have been a mess-up with the burst function timing - or would burst have nothing to do with jams? Maybe the build up of BBs pushing the nozzle back and jamming the flow of things in the gearbox? I could brainstorm all day. Just want to get some opinions before opening her up. Thanks.

[Stealth]

Try the gun without the MERF

Are the BBs jammed or the gearbox is jammed?

Does the gearbox sound like it's trying to wind or is there no sound at all?

[-Shade]

Originally Posted by Stealth

Try the gun without the MERF

Are the BBs jammed or the gearbox is jammed?

Does the gearbox sound like it's trying to wind or is there no sound at all?

Gearbox is jammed - def not the BBs. (removed the gearbox to try it)
Doesn't work even without the MERF.
There's a very slight, quiet sound of the motor trying to turn, but no sound at all from the gearbox.

Any gun docs willing to look at this?

[lurkingknight]

badly shimmed gears will break or bend an axle, or stretch a bearing if the gearbox is completely jammed at the moment and won't release then you've probably bent or broken something inside.

[Stealth]

Going to have to agree with the suggestion above.

Open it up and see. If it's not turning over and the motor is making a noise, then:
1) Your battery is dead (needs charging or is completely done); and/or
2) something is jamming up the gears in the mechbox - in which case you should stop trying so you avoid #1

[-Shade]

Thank you all, I'll definitely look into that tonight and post my findings

[-Shade]

Sorry if this is a double post.

Later that night...

- So I took my box apart and surprisingly none of the gears were broken/bent in any way.
- I re-shimmed and as I was turning my gears and aligning them with the piston, I found that my piston teeth were damaged!
- on the third/fourth tooth it looks like the gear had crushed the plastic and won't fit in between the teeth anymore
- So essentially it got stuck!

What could have caused this? A bad AoE?

Would filing the spaces in between the teeth solve this issue? Or do I need a new piston altogether? How can I avoid this from happening again?

Any help would be greatly appreciated.

[lurkingknight]

if it's still apart, can you take another pic with the gear mesh and pistion full forward?

When you took it apart, was it jammed midcycle? would the arl release the gears completely or was it still stuck mid cycle?

[zone 69]

That kind of damage can be from the BB jam. the BB jam slowed the piston down and the gear engaged to early on the piston.

Keep your barrel clean and use quality BB,s to help avoid jamming.

But you need a new piston now. IMO guarder pistons suck, I use TM pistons and they seem to be better then most at there price point.

[-Shade]

Originally Posted by lurkingknight

if it's still apart, can you take another pic with the gear mesh and pistion full forward?

When you took it apart, was it jammed midcycle? would the arl release the gears completely or was it still stuck mid cycle?

I didn't get to see. I'm assuming it was stuck midcycle cause as soon as I opened it up, the piston shot outwards.

Originally Posted by zone 69

That kind of damage can be from the BB jam. the BB jam slowed the piston down and the gear engaged to early on the piston.

Keep your barrel clean and use quality BB,s to help avoid jamming.

But you need a new piston now. IMO guarder pistons suck, I use TM pistons and they seem to be better then most at there price point.

I had just bought a new prommy barrel + bucking and I'm thinking that I may not have set it up correctly with the hop-up, which caused my jam. Could my bucking be damaged at all? They seem very resilient considering what they are made from.

I bought a new SHS 15 teeth piston recommended to me by the great guys at airsoft store canada. I'm going to be re-shimming, reinstalling the bucking, cleaning the barrel, and be very thorough in general.

Also, I use the madbull eco BBs that come in the milk cartons. I assume them to be high quality.

[zone 69]

I think its the BB,s you need to change try some BB bastards.

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Originally Posted by zone 69

I think its the BB,s you need to change try some BB bastards.

Ugh - somehow I feel like these new Madbull PLA bio BBs are utter crap.

[Stealth]

Uhhh.....yeah I don't think many people use those BBs.
Any specific reason why you're using Bio? (besides specific field requirements)

Take some pictures of the hop-up unit and make sure the hop rubber lips aren't deformed or folded in. I keep saying this but - not all rubbers/barrels/hop units are designed to work together so it's paramount to do a visual check before testing.

[-Shade]

Originally Posted by Stealth

Uhhh.....yeah I don't think many people use those BBs.
Any specific reason why you're using Bio? (besides specific field requirements)

Take some pictures of the hop-up unit and make sure the hop rubber lips aren't deformed or folded in. I keep saying this but - not all rubbers/barrels/hop units are designed to work together so it's paramount to do a visual check before testing.

It's field required. That's really the only reason, haha. I won't be able to look into it until tomorrow, but I will post pictures if something is out of the ordinary.