CA M4 fires but doesn't fire...

gkagan · February 16th, 2011, 21:46

which is to say:

I have a ca. 2005 CA M4. It was stock and running fine, and I decided to switch to LiPo and put in a MOSFET. When I disassembled it, I noticed that the cylinder head was actually broken, so I replaced it with a brass one from element. I wired in an AWS Pulse FET unit and reassembled the gun w/o problems.

Now, the gearbox runs fine, nice ROF, smooth motor sound, etc., but when I fully reassemble the AEG, it won't fire. I get the gearbox whirring away going popopop, but I get that dead "the barrel is blocked" sound. It *seems* like the nozzle isn't pushing into the hopup unit appropriately to seal with the hopup rubber, and I know this causes huge problems for lots of people. It appears that the spring ont he tappet plate isn't strong enough to push the nozzle into the hopup. When I have the mechbox out of the gun, the nozzle flies back and forth no problem. It only happens when i put it into the hopup unit. If I load the magazine tube with bbs, and fire, they all shoot out violently.

So, PLEASE tell me: have I correctly identified the problem and if so, how the hell do I fix it. The cylinder and piston heads are the only things I've changed, and the nozzle moving when running disassembled would indicate to me that it is not getting stuck on the new cylinder head.

Thank you

Blacksheep · February 16th, 2011, 21:54

gear timing is off and your hop up needs to be replaced or lubed, take out the barrel will the rubber attached if u can blow a bb through and it leaves the barrel good then that part is fine.

HKGhost · February 16th, 2011, 22:34

what the hell is gear timing? There is no such thing in airsoft.

Styrak · February 17th, 2011, 00:11

Quote:

Originally Posted by Blacksheep

gear timing is off

There is no such thing.
Stop spreading this misinformation.

gkagan · February 17th, 2011, 00:21

Thanks for your posts.

I thought about timing and decided a long time ago I don't think it matters.

FWIW, if I jiggle the hopup unit, I can get it to run fine, but once I slide the gearbox all the way forward against the hopup, the nozzle just won't go in.

Zep · February 17th, 2011, 00:46

I had the same thing happen to me with my M4.

Make sure it has a good air seal, the spring on my hop-up, bore was bent for some reason so it wasn't coming back or move at all. therefore the bbs were getting stuck. i took the spring out of a pen and it works great now lol.

I suck at explaining things hope this made a little sense, if not someone please try to explain what i said..

hahaha

ThunderCactus · February 17th, 2011, 19:49

Try it with a less powerful battery, your tappet plate might not be moving fast enough to handle the high ROF

Blacksheep · February 17th, 2011, 19:53

June 22nd, 2005, 09:41 #6
airsoftpress

Join Date: Feb 2005 It is widely believed that you need to set your sector gear with the tappet plate post at the one o'clock position when reassembling your mechbox.

Although doing it this way doesn’t hurt, it does not have to be strictly "one o'clocked". Think about it, the sector gear is a half-toothed gear which has multiple teeth partially formed on the periphery and an idle area formed on the remainder of the periphery. This design is supposed to provide an optimal means for pulling the piston into a compressed position when needed. When idle, the teeth formed on the periphery are not in touch with the piston. When you pull the trigger, the sector gear is driven anti-clockwise, which eventually will have its teeth getting in touch with the piston. This is when all the actions get started. Effectively, this mean the gear system will time the gears properly by itself.

What we are trying to say is that as long as the sector gear is in a position where all the teeth are facing downward (a position anywhere between 12:30 and 3:00, such that no tooth is in touch with the piston at the time of installation), it will do fine. Still, by having the gear "one o'clocked", you can enjoy a slightly faster initial response time (and peace of mind too). That’s all.

REfer to: http://www.airsoftpress.com/aegupg.htm
__________________
We want anything published by AirsoftPRESS to be useful, interesting, and truthful.
http://www.airsoftpress.com 8)

Blacksheep · February 17th, 2011, 19:54

thats what was posted here on the site and on mechbox.com so??
gear timing?? so this site not me is spreading miss information so thanks for acussing me i was just trying to help>

ThunderCactus · February 17th, 2011, 20:07

Think about it rationally, in order to have any sort of timing in a geared system, you need more than one gear to have a control feature. Like your piston would have to be run off the sector gear, and the tappet plate off the spur gear.
But all the actions are performed by the sector gear alone, and so there's zero timing involved.

The phrase was used by someone who didn't understand what they were talking about, because gear timing very specifically refers to aligning gears to each other.

What your actually doing when putting the sector gear out of the way of the tappet and piston when assembling a mechbox is "putting the sector gear in a neutral position", or "making sure the sector gear isn't engaging with anything"

We know mechbox.com poorly worded it, but nobody's done anything about the video, and we're just saying, there's no such thing as gear timing lol

Blacksheep · February 17th, 2011, 20:34

no worrys
just dont enjoy bieng flammed for somthing i read on here,and anyhow its all ok

CDN_Stalker · February 17th, 2011, 20:47

Quote:

Originally Posted by gkagan

Thanks for your posts.

I thought about timing and decided a long time ago I don't think it matters.

FWIW, if I jiggle the hopup unit, I can get it to run fine, but once I slide the gearbox all the way forward against the hopup, the nozzle just won't go in.

FYI, the gears, tappet plate, anti-reversal latch, etc. pretty much time themselves when the gun is first cycled after reassembly.

gkagan · February 18th, 2011, 11:53

I agree that it times itself, but also like Blacksheep said, it can't hurt.

I suspect that the old nozzle is tighter on the new cylinder head than the old one, and is sticking when in the hopup, but not when disassembled.

I dropped it off at a smith yesterday and said "go nuts". I'd rather pay the $30 for him to diagnose and fix it than shotgun $50 worth of parts at it and maybe not fix it!

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February 16th, 2011, 21:46	#1
gkagan Trader rating Join Date: Apr 2009 Location: Massachusetts, USA	CA M4 fires but doesn't fire... which is to say: I have a ca. 2005 CA M4. It was stock and running fine, and I decided to switch to LiPo and put in a MOSFET. When I disassembled it, I noticed that the cylinder head was actually broken, so I replaced it with a brass one from element. I wired in an AWS Pulse FET unit and reassembled the gun w/o problems. Now, the gearbox runs fine, nice ROF, smooth motor sound, etc., but when I fully reassemble the AEG, it won't fire. I get the gearbox whirring away going popopop, but I get that dead "the barrel is blocked" sound. It seems like the nozzle isn't pushing into the hopup unit appropriately to seal with the hopup rubber, and I know this causes huge problems for lots of people. It appears that the spring ont he tappet plate isn't strong enough to push the nozzle into the hopup. When I have the mechbox out of the gun, the nozzle flies back and forth no problem. It only happens when i put it into the hopup unit. If I load the magazine tube with bbs, and fire, they all shoot out violently. So, PLEASE tell me: have I correctly identified the problem and if so, how the hell do I fix it. The cylinder and piston heads are the only things I've changed, and the nozzle moving when running disassembled would indicate to me that it is not getting stuck on the new cylinder head. Thank you

February 16th, 2011, 21:54	#2
Blacksheep Trader rating Join Date: Jul 2007 Location: Okanagan BC	gear timing is off and your hop up needs to be replaced or lubed, take out the barrel will the rubber attached if u can blow a bb through and it leaves the barrel good then that part is fine. __________________ Your brain is your best defence. Your weapon and effective use of command and control tactics immediately puts you on an equal or superior offensive footing.

February 16th, 2011, 22:34	#3
HKGhost Trader rating Join Date: Nov 2009 Location: Mississauga, ON	what the hell is gear timing? There is no such thing in airsoft. __________________ Please email me as I'm not on ASC too often. Custom Build \| Upgrades \| Repairs \| Maintenance Contact: ghostgunwork@gmail.com / Private Message

February 17th, 2011, 00:21	#5
gkagan Trader rating Join Date: Apr 2009 Location: Massachusetts, USA	Thanks for your posts. I thought about timing and decided a long time ago I don't think it matters. FWIW, if I jiggle the hopup unit, I can get it to run fine, but once I slide the gearbox all the way forward against the hopup, the nozzle just won't go in.

February 17th, 2011, 00:46	#6
Zep Trader rating Join Date: Jan 2011 Location: CFB Petawawa	I had the same thing happen to me with my M4. Make sure it has a good air seal, the spring on my hop-up, bore was bent for some reason so it wasn't coming back or move at all. therefore the bbs were getting stuck. i took the spring out of a pen and it works great now lol. I suck at explaining things hope this made a little sense, if not someone please try to explain what i said.. hahaha __________________ Magpul G&P M4 Carbine King Arms Knight's SR-16 Carbine Team: Delta 5. ASO Username: Maniak **************************

February 17th, 2011, 19:49	#7
ThunderCactus Not Eye Safe, Pretty Boy Maximus on the field take his picture! Trader rating Join Date: Feb 2007	Try it with a less powerful battery, your tappet plate might not be moving fast enough to handle the high ROF

February 17th, 2011, 19:53	#8
Blacksheep Trader rating Join Date: Jul 2007 Location: Okanagan BC	June 22nd, 2005, 09:41 #6 airsoftpress Join Date: Feb 2005 It is widely believed that you need to set your sector gear with the tappet plate post at the one o'clock position when reassembling your mechbox. Although doing it this way doesn’t hurt, it does not have to be strictly "one o'clocked". Think about it, the sector gear is a half-toothed gear which has multiple teeth partially formed on the periphery and an idle area formed on the remainder of the periphery. This design is supposed to provide an optimal means for pulling the piston into a compressed position when needed. When idle, the teeth formed on the periphery are not in touch with the piston. When you pull the trigger, the sector gear is driven anti-clockwise, which eventually will have its teeth getting in touch with the piston. This is when all the actions get started. Effectively, this mean the gear system will time the gears properly by itself. What we are trying to say is that as long as the sector gear is in a position where all the teeth are facing downward (a position anywhere between 12:30 and 3:00, such that no tooth is in touch with the piston at the time of installation), it will do fine. Still, by having the gear "one o'clocked", you can enjoy a slightly faster initial response time (and peace of mind too). That’s all. REfer to: http://www.airsoftpress.com/aegupg.htm __________________ We want anything published by AirsoftPRESS to be useful, interesting, and truthful. http://www.airsoftpress.com 8) __________________ Your brain is your best defence. Your weapon and effective use of command and control tactics immediately puts you on an equal or superior offensive footing.

February 17th, 2011, 19:54	#9
Blacksheep Trader rating Join Date: Jul 2007 Location: Okanagan BC	thats what was posted here on the site and on mechbox.com so?? gear timing?? so this site not me is spreading miss information so thanks for acussing me i was just trying to help> __________________ Your brain is your best defence. Your weapon and effective use of command and control tactics immediately puts you on an equal or superior offensive footing.

February 17th, 2011, 20:07	#10
ThunderCactus Not Eye Safe, Pretty Boy Maximus on the field take his picture! Trader rating Join Date: Feb 2007	Think about it rationally, in order to have any sort of timing in a geared system, you need more than one gear to have a control feature. Like your piston would have to be run off the sector gear, and the tappet plate off the spur gear. But all the actions are performed by the sector gear alone, and so there's zero timing involved. The phrase was used by someone who didn't understand what they were talking about, because gear timing very specifically refers to aligning gears to each other. What your actually doing when putting the sector gear out of the way of the tappet and piston when assembling a mechbox is "putting the sector gear in a neutral position", or "making sure the sector gear isn't engaging with anything" We know mechbox.com poorly worded it, but nobody's done anything about the video, and we're just saying, there's no such thing as gear timing lol

February 17th, 2011, 20:34	#11
Blacksheep Trader rating Join Date: Jul 2007 Location: Okanagan BC	no worrys just dont enjoy bieng flammed for somthing i read on here,and anyhow its all ok __________________ Your brain is your best defence. Your weapon and effective use of command and control tactics immediately puts you on an equal or superior offensive footing.

February 18th, 2011, 11:53	#13
gkagan Trader rating Join Date: Apr 2009 Location: Massachusetts, USA	I agree that it times itself, but also like Blacksheep said, it can't hurt. I suspect that the old nozzle is tighter on the new cylinder head than the old one, and is sticking when in the hopup, but not when disassembled. I dropped it off at a smith yesterday and said "go nuts". I'd rather pay the $30 for him to diagnose and fix it than shotgun $50 worth of parts at it and maybe not fix it!

CA M4 fires but doesn't fire...

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