Two Cycles Problems

Discussion in 'Gun Building, Modifications & Repairs' started by PistolsAndMP5s, Sep 17, 2012.

  1. PistolsAndMP5s

    PistolsAndMP5s New Member

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    My M4 is shooting two cycles when I shoot it. I can hear two cycles in the gearbox when firing. The weird thing is that when I don't have a magazine in the gun, and I dry fire, it never cycles twice. When I DO have the magazine in my gun, then sometimes it shoots two cycles. So it is not necessarily a double feed.
    Any help identifying the problem?
    Thanks
     
  2. EDI1st

    EDI1st New Member

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    Using a high voltage or discharge rate lipo I assume?
     

  3. PistolsAndMP5s

    PistolsAndMP5s New Member

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    Only a 9.6v 1600mAH.
    Not very high voltage
     
  4. EDI1st

    EDI1st New Member

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    Have you checked the cut off lever and the spring?
     
  5. PistolsAndMP5s

    PistolsAndMP5s New Member

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    No i haven't but the weird thing is that when I dry fire it doesn't cycle twice but when a magazine is in then it does it every 5 shots. Any explanation? I've searched google but can't seem to find a similar problem.
     
  6. alex

    alex New Member

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    what's your fps? weaker springs with 9.6v tend to overspin. when you put the magazine in, is it empty or full of bb's? bb's in the chamber will add compression to the cylinder which affects the gearbox.

    if the magazine is empty, then you have a cursed gearbox. sell it or you will die a horrible death.

    btw, how old is your gun? did you buy it used?
     
  7. PistolsAndMP5s

    PistolsAndMP5s New Member

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    Gun is 8 months old. I'm using a JG Blue motor, with 13:1 gears. The gun shoots 290ish on .20.
    When I put the mag in it is full of BBs.
     
  8. alex

    alex New Member

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    high speed gears + low fps = over spin (fps at 300)
    high speed gears + higher rate spring + short stroking = no overspin (fps adjusted to 300)

    short stroking = removing pickup tooth from sector gear to reduce fps
    or, you can add an AB mosfet to stop the over spin (not efficient as short stroking).

    there are better ways to get 300fps/20rps,
     
  9. PistolsAndMP5s

    PistolsAndMP5s New Member

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    Hmm. Do you think a M120 with shortstroking will get me to around 340ish?
     
  10. alex

    alex New Member

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    you can short stroke to whatever fps you want...
    before attempting to short stroke read up on:
    AOE adjustment
    mosfets
    deans xtc connnectors
    LiPo
    shimming
    gearbox radiusing
    airsealing

    tuning up your gearbox makes it more efficient.
     
  11. PistolsAndMP5s

    PistolsAndMP5s New Member

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    What would happen if I put in a stiffer spring WITHOUT short stroking? Would this still solve preengagement?
     
  12. Mystery43_4

    Mystery43_4 New Member

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    YES, but you'd also raise your FPS.
     
  13. PistolsAndMP5s

    PistolsAndMP5s New Member

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    Ok thanks for your help.
     
    Last edited: Oct 16, 2012
  14. Mystery43_4

    Mystery43_4 New Member

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    Yep. Also note that bumping up spring rates doesn't necessarily mean that you'll fix the double cycle.

    If you're running an m80 and bump up to an m90, it probably won't fix it...

    Bumping up from an M120 to an M130 probably will though...
     
  15. PistolsAndMP5s

    PistolsAndMP5s New Member

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    Yeah I'm running an M100 in there. I'm sure I have a spare M110 or M120 here somewhere. I'll post an update after installation. If this doesn't fix it, I guess I'll replace the cut-off lever.
     
  16. Mystery43_4

    Mystery43_4 New Member

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    Cut off lever, cut off lever spring, Sector gear if need be.

    Pry apart your trigger contacts a bit. It will help stop the current flow a few thousandths of a second faster.
     
  17. PistolsAndMP5s

    PistolsAndMP5s New Member

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    UPDATE:
    Spring Installation did not help. Will be purchasing a new cut-off lever, but am very limited due to Ares proprietary cut-off lever. Going to be getting the Army Force with is supposed to be in Matrix QD Transform Gearbox which is a supposedly an ARES Gearbox clone.
    Hope this works~
     
  18. alex

    alex New Member

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    oh, ares... wish you would have mentioned that. the microswitch cutoff spring combination is finicky. you may need a stronger cutoff spring. sorry, no pics for ares m4 versions.

    try cleaning all the grease off the trigger switch assemblies.
     
  19. PistolsAndMP5s

    PistolsAndMP5s New Member

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    Do you believe this cut-off lever will work? And will is the cut-off lever spring proprietary? Darn you ARES haha
     
  20. alex

    alex New Member

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    the micro switch is very sensitive. it's hard for me to explain because it's easy for me to adjust when it switches on/off by filing down parts. in your case, it may be as simple as replacing the micro switch. there are a number of springs that control the trigger system. some may need to be stiffen or loosen. i can only adjust it if it was on my workbench.

    the micro switch i linked to has extra levers that can be removed easily. just use an exacto blade to split the cover apart. the stock ones get damaged easily because of their low amp rating. micro switches require mosfets.
     
    Last edited: Nov 14, 2012