Gearbox Piston Lock Up?

Discussion in 'Gun Building, Modifications & Repairs' started by kwasr10, Sep 28, 2012.

  1. kwasr10

    kwasr10 New Member

    Hi, I recently upgraded my kwa sr10. I wanted more fps out of it so i got a tight bore barrel, a G&P M170 Devil Jet motor, a new Piston, Piston head, Cylinder head/Air nozzle, and guarder sp130 spring. I put everything together and then tried firing it. it fired once and then i tried it again and the piston pulled all the way back and did not release. it got stuck and wouldn't shoot. i took it all back apart and reassembled it and the same exact thing happened. i use a 9.6volt battery and they were fully charged. i then tried putting in the original m120 and it shoots fine but it keeps locking up every couple of days. I know i put everything together right the only thing i did to the gears was shim the spur gear. I am thinking of putting in the madbull m130 spring. why is it locking up?
    Please help
  2. Lefse

    Lefse Well-Known Member Supporting Member

    If you are 100% sure that the shimming isn't too tight, and the motor isn't a lemon, then it points towards your battery? Whats the capacity of the battery, how old is it, what brand is it, why are you not using a li-po?

  3. kwasr10

    kwasr10 New Member

    I am sure that the shimming is good and the motor is rated for an m170 so its gotta be the battery. I use a 9.6 volt battery 1600 maH, my batteries are about 2 years old. I don't have a li-po because first of all i don't have a charger for it and i don't know which one will fit my crane stock. Also i would like another alternitave like a 10.8 battery. will adding a couple extra cells to my battery work?
  4. alex

    alex New Member

    get it chrono'd. sp130 normally hits 430-450 fps. if you are using a heavier spring to compensate for an air leak, then you are doing more harm than good. what is your target fps? increasing the voltage will increase the rps. if you haven't corrected your AOE, expect piston damage. i'm going to assume it's the stock piston.

    increasing performance increases the amp load. you will most likely need to upgrade your wiring to handle the load (prevents wires from heating up). tamiya's are not good at handling high amp loads. they like to melt down. replace your battery with a new 9.6v.
  5. kwasr10

    kwasr10 New Member

    First can you please read all the reviews because my first one has all the info on it that you asked for and i am looking to get about 450 fps. I am currently getting 312 fps but i have 100% compression. I also have a Sw-Cheetah mosfet computer
  6. EDI1st

    EDI1st New Member

    Fountain Valley
    lmfao....100% compression my ***....... you even know what 130 means?

    130 m/s, which is about 400fps, but Guarder underrate their spring a lil bit.
    So Alex is RIGHT.

    Please stop acting like you think you are good at this.
    Because if you are, you won't even be posting this type of stuffs here.

    Well, here are couple things that you could have done wrong.
    1. You got a KWA. (This one is for sure just wrong)
    2. You didn't shim properly and/or didn't adjust the motor height properly. (I'm just going to go ahead and say this one is wrong too)
    3. You have massive compression issue. (Yea, this one is definitely wrong, 312 fps and saying you have 100% compression, what a joke.)
    4. You didn't read the fine print about the Cheetah.
  7. Shiftyshooter

    Shiftyshooter Learn from your mistakes. Lifetime Supporter

    KWASR10, reporting a post that is being helpful is just rude. Stop acting like a little child and listen to people who know what they are saying. Unlike you.
  8. bbattlefield

    bbattlefield New Member

    No, don't listen to the people that have nothing better to do than hate on kwa. That sounds like a battery to me. I made a DMR build out of mine also, same thing happened. I popped in a 11.1v and it worked great. I replaced most parts inside of the gearbox and my SR-10 still works great. That was 2 years ago also.
    EDIT: I actually have that exact same spring. It was shooting close to 500 fps with mine. If yours really is shooting 312, something big is up.

    As what Alex said, better wires would probably be better and the amps make a difference also. I run stock wires with no problem, but mine are pretty heavy gauge compared to other brands. For example, my friends 10.8v is only .3 volts difference, right? But a lipo 11.1 performs a lot better than his battery because it has more amps or a higher discharge rate. (Correct me if I'm wrong)
    Last edited: Oct 4, 2012