Why my AEG is weak after I opened the gearbox?

mirrage · May 10th, 2009, 05:19

Hi all!

I recently opened the gearbox of my D-Boys M4 RIS and after I fixed the
cracked spring guide I closed it.
The problem is that after I closed it and replaced it the AEG is weak.
In fact is much weaker than the 350 fps it should shoot.
The bbs can't even penetrate a cardboard wich was easy to penetrate before!
I check the piston head looked ok as well as the gears shim, alignment ,
cylinder alignment and the nozzle.
All the work I did was just remove and replace the parts no upgrades other
adjustments.
There is no dust or other fragments that may block the gears.
I can't figure out what is the problem and I have already opened the gearbox
twice.

What may cause this weakness?

Thank you in advance for your help!

prepaidpwnage · May 10th, 2009, 08:04

First off, this probably belongs in the gun doc section.

Sounds like a compression issue to me. It could be a ripped O-ring some where, or one may have dried out. If you open it again, do a compression test. Take out your cylinder, cylinerhead and put your finger over the hole while trying to push the piston/piston head down the cylinder. It should be difficult. Then recheck all the O-rings and fittings. If you need new ones size 14 should do the job perfectly.
If you haven't already, clean out all the crappy dboys grease and then re lube it.

mirrage · May 10th, 2009, 09:13

It sounds like compression issue to me to.
The o-rings are the rubber rings around the piston
head that ensure insulation?
If yes then i think that they are all fine.i have to check
again and be sure.I did put my finger in the hole and fire a
few shoots but it was easy and my finger didn't move.
I will try what you suggest and move the piston by hand.

When I sealed the gearbox I didn't grease it and left only
the d-boys grease in there but I try to find if the grease that
was taken off by touch is the cause of the problem.
While firing the piston stack a few times.Is this a greasing issue?

Skruface · May 10th, 2009, 10:38

Spring in backwards? (It makes a difference with some springs)
Cylinder port at wrong end? (the hole in the cylinder should be at the rear)

If the piston is getting stuck, it's not likely a lube issue, but a piston or gearbox shell issue.

prepaidpwnage · May 10th, 2009, 11:23

i still think it could be an issue with O-rings. The only reason I mention lube is because the Chinese clones use a ton of cheap lube and if you are in there, you might as well clean it out and re lube.

Did you check your compression?

mirrage · May 10th, 2009, 13:14

I just have checked the compression and found it not to difficult to push the piston in the cylinder.
I also found that the rubber ring around the piston head is loose.Not broken but loose.

viraL · May 10th, 2009, 14:12

Did you take the hopup out? Or play with that at all? If you lost the spring or didn't put it back, youll get weak results. Try opening the dust cover and pushing the hopup against the gearbox and taking a shot, watch what it does. If it doesnt reseat itself (may take a few shots to move it) then you're missing the spring which pushes against the hopup to get a good airseal between the nozzle and the hopup.

mirrage · May 10th, 2009, 14:55

The hop-up spring is in place.

viraL · May 10th, 2009, 15:12

Get some silicone oil (read, SILICONE OIL, 100% SILICONE, NOTHING BUT. If it has petroluem distillates it will ruin anything rubber in your gun, aka what im telling you to use it on) or white lithium grease (spray format or tube, doesnt matter. I prefer spray for this) and coat the oring and the part of the piston head the oring sits in. It might just be dry and not getting a good seal. This will cause the oring to beef up a little bit (if it was dry) and the extra lube will help great a good seal and keep things moving properly.

prepaidpwnage · May 10th, 2009, 17:50

If you need to replace the O-ring on the piston head a size # 14 should do fine from what I've heard.

lemegacool · May 10th, 2009, 18:07

its ok for the piston head oring to be loose, is it lubed? if your piston head oring isnt lubed (like you wiped it off to "clean" it) it can cause a great fps drop, also as said if you hane a non-liner spring and you putted it backward it could also caus fps drop (the spring is supposed to have a section with more coils, this section is going on the spring guide, not in the piston)

Cheeseman · May 10th, 2009, 18:10

Check:

- if your piston head is loose or not
- spring in backwards or not (the end with the condensed coils has to go to the back of the spring guide)
- oiled or not cylinder
- hopup dialed too much and or hopup rubber ripped.
- oring has seal on the cylinder head
- nozzle is not cracked

Point_Man · May 10th, 2009, 21:25

Also check that the air nozzle is properly seated at the end of the tappet plate. If it isn't, the nozzle will move freely and not create a proper seal.

mirrage · May 11th, 2009, 05:00

I will lube it.That's for sure.
As for the spring I checked it and both sides are the same.
The nozzle although not cracked it is loose as well but I found no sealing rubber or what so ever.Is it supposed to have something like a rubber to
help it seal and seat in place?

Point_Man · May 11th, 2009, 10:14

There's no rubber. When the nozzle is in place, it should move, but only with the tappet plate. It sits in a rounded groove at the front end of the tappet plate.

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May 10th, 2009, 05:19	#1
mirrage Trader rating Join Date: May 2009 Location: Athens, Greece	Why my AEG is weak after I opened the gearbox? Hi all! I recently opened the gearbox of my D-Boys M4 RIS and after I fixed the cracked spring guide I closed it. The problem is that after I closed it and replaced it the AEG is weak. In fact is much weaker than the 350 fps it should shoot. The bbs can't even penetrate a cardboard wich was easy to penetrate before! I check the piston head looked ok as well as the gears shim, alignment , cylinder alignment and the nozzle. All the work I did was just remove and replace the parts no upgrades other adjustments. There is no dust or other fragments that may block the gears. I can't figure out what is the problem and I have already opened the gearbox twice. What may cause this weakness? Thank you in advance for your help! Last edited by mirrage; May 10th, 2009 at 05:23..

May 10th, 2009, 18:07	#11
lemegacool Trader rating Join Date: Aug 2008 Location: notre dame des prairies /quebec	its ok for the piston head oring to be loose, is it lubed? if your piston head oring isnt lubed (like you wiped it off to "clean" it) it can cause a great fps drop, also as said if you hane a non-liner spring and you putted it backward it could also caus fps drop (the spring is supposed to have a section with more coils, this section is going on the spring guide, not in the piston) __________________ member of fire team NOM. my other regular forum: www.toyotanation.com / gen3,gen4 camry

May 10th, 2009, 08:04	#2
prepaidpwnage Trader rating Join Date: Jan 2009 Location: New Jersey, USA	First off, this probably belongs in the gun doc section. Sounds like a compression issue to me. It could be a ripped O-ring some where, or one may have dried out. If you open it again, do a compression test. Take out your cylinder, cylinerhead and put your finger over the hole while trying to push the piston/piston head down the cylinder. It should be difficult. Then recheck all the O-rings and fittings. If you need new ones size 14 should do the job perfectly. If you haven't already, clean out all the crappy dboys grease and then re lube it.

May 10th, 2009, 09:13	#3
mirrage Trader rating Join Date: May 2009 Location: Athens, Greece	It sounds like compression issue to me to. The o-rings are the rubber rings around the piston head that ensure insulation? If yes then i think that they are all fine.i have to check again and be sure.I did put my finger in the hole and fire a few shoots but it was easy and my finger didn't move. I will try what you suggest and move the piston by hand. When I sealed the gearbox I didn't grease it and left only the d-boys grease in there but I try to find if the grease that was taken off by touch is the cause of the problem. While firing the piston stack a few times.Is this a greasing issue?

May 10th, 2009, 11:23	#5
prepaidpwnage Trader rating Join Date: Jan 2009 Location: New Jersey, USA	i still think it could be an issue with O-rings. The only reason I mention lube is because the Chinese clones use a ton of cheap lube and if you are in there, you might as well clean it out and re lube. Did you check your compression?

May 10th, 2009, 13:14	#6
mirrage Trader rating Join Date: May 2009 Location: Athens, Greece	I just have checked the compression and found it not to difficult to push the piston in the cylinder. I also found that the rubber ring around the piston head is loose.Not broken but loose.

May 10th, 2009, 14:12	#7
viraL Envies Disaster_Piece's hair Trader rating Join Date: Feb 2009 Location: Burlington, ON	Did you take the hopup out? Or play with that at all? If you lost the spring or didn't put it back, youll get weak results. Try opening the dust cover and pushing the hopup against the gearbox and taking a shot, watch what it does. If it doesnt reseat itself (may take a few shots to move it) then you're missing the spring which pushes against the hopup to get a good airseal between the nozzle and the hopup.

May 10th, 2009, 14:55	#8
mirrage Trader rating Join Date: May 2009 Location: Athens, Greece	The hop-up spring is in place.

May 10th, 2009, 15:12	#9
viraL Envies Disaster_Piece's hair Trader rating Join Date: Feb 2009 Location: Burlington, ON	Get some silicone oil (read, SILICONE OIL, 100% SILICONE, NOTHING BUT. If it has petroluem distillates it will ruin anything rubber in your gun, aka what im telling you to use it on) or white lithium grease (spray format or tube, doesnt matter. I prefer spray for this) and coat the oring and the part of the piston head the oring sits in. It might just be dry and not getting a good seal. This will cause the oring to beef up a little bit (if it was dry) and the extra lube will help great a good seal and keep things moving properly.

May 10th, 2009, 17:50	#10
prepaidpwnage Trader rating Join Date: Jan 2009 Location: New Jersey, USA	If you need to replace the O-ring on the piston head a size # 14 should do fine from what I've heard.

May 10th, 2009, 18:10	#12
Cheeseman Trader rating Join Date: Oct 2008 Location: Toronto, Ontario, Canada	Check: - if your piston head is loose or not - spring in backwards or not (the end with the condensed coils has to go to the back of the spring guide) - oiled or not cylinder - hopup dialed too much and or hopup rubber ripped. - oring has seal on the cylinder head - nozzle is not cracked

May 10th, 2009, 21:25	#13
Point_Man Trader rating Join Date: Dec 2001 Location: Ottawa, Ontario	Also check that the air nozzle is properly seated at the end of the tappet plate. If it isn't, the nozzle will move freely and not create a proper seal.

May 11th, 2009, 05:00	#14
mirrage Trader rating Join Date: May 2009 Location: Athens, Greece	I will lube it.That's for sure. As for the spring I checked it and both sides are the same. The nozzle although not cracked it is loose as well but I found no sealing rubber or what so ever.Is it supposed to have something like a rubber to help it seal and seat in place?

May 11th, 2009, 10:14	#15
Point_Man Trader rating Join Date: Dec 2001 Location: Ottawa, Ontario	There's no rubber. When the nozzle is in place, it should move, but only with the tappet plate. It sits in a rounded groove at the front end of the tappet plate.

Why my AEG is weak after I opened the gearbox?

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