Jump to content


MP7 Rocket Valve Problems


  • Please log in to reply
2 replies to this topic

#1 Najentus

Najentus

    Newbie

  • Members
  • Pip
  • 3 posts

Posted 21 August 2010 - 03:06 PM

I have a KWA MP7 that's been having some weird FPS and range variations depending on the angle at which you hold it, after inspecting the bold I noticed that the rocket valve's spring seemed to have disappeared and promptly removed the bolt from the gun only to see the spring resting inside the nozzle, just much further forward of the original position.  This cause the valve to move freely depending on what angle the gun was at when firing.  If you pointed the gun at a downward angle, the valve would slide forward, and close up the front of the nozzle and allow no air into the barrel to propel the BB, thus causing the gun to cycle as if it was in good condition, but not actually fire a round.  If you pointed the gun at an upward angle the valve would slide back to the position it was normally supposed to be in, and would have relatively normal FPS and range, if the gun was held level, it worked normally about 90% of the time in semi, and on full auto would misfire but still cycle about 20% of the time, cause two rounds to be discharged after a cycling of the bolt when no air was allowed to enter the barrel because of the valve.  I then (because my warranty was up) removed the bolt from the gun and disassembled and removed the nozzle.  This was made slightly difficulty by how hard it was to remove the block that prevented the nozzle from moving too far forward, I removed a tiny bit of metal from the side surfaces to make it fit without the need for me to hammer it to get it back in.  After removing the pin from the nozzle to get at the valve, I looked down into the nozzle and saw that the spring in fact had not been lost, but was seated much further forward in the chamber than it should have been.  I managed to get it out and then dropped it back in with the nozzle and replaced the pin and it appeared that it was fixed.  I reassembled the bolt, and then the gun itself, and test fired it, it appeared to have been fixed because firing at a downward angle no longer caused the gun to cycle without firing.  After every 5 rounds I would remove the magazine and shine a light into the magazine well to see if the spring had once again disappeared.  After the 30th round I was dismayed when I looked into the grip and the spring had disappeared once again and the original problems returned.  I removed the bolt from the gun again and could once again see the spring sitting far forward in the chamber of the nozzle.  I would like to know what parts I would need to replace to cause this problem to cease to happen.  I can do the repairs on my own and was already informed by someone at the help desk how to send it in for diagnostics should I be unable to fix it myself.  The link below is a picture of the valve free in the chamber, and the red arrow points to the spring inside the chamber.

http://www.xstalmedi...33860084981.jpg

#2 Spiggy

Spiggy

    Member

  • Members
  • PipPipPipPip
  • 2,136 posts
  • Gender:Male
  • Location:City of Industry
  • Country:

Posted 23 August 2010 - 12:26 PM

take the spring out and turn it around.  Try that

#3 Najentus

Najentus

    Newbie

  • Members
  • Pip
  • 3 posts

Posted 23 August 2010 - 01:11 PM

View PostSpiggy, on 23 August 2010 - 12:26 PM, said:

take the spring out and turn it around.  Try that

    I actually did that yesterday and it seems to have fixed the problem, will repost if it returns.  

Thanks.




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users