Gearbox piston jam in compressed position

[patrykj26]

Hello,

 

I have a Specna arms SA-BO3 and my piston seems to jam in the outward position (when the spring is fully compressed) only way i found to fix my problem temporarily is to loosen the bolt that holds the spring in. not ideal as its now less powerful. any suggestions. i have stripped and rebuilt the gearbox nothing looked damaged. piston moves freely in the cylinder. gun jams when in fully auto or quick single fire.

[Colin Allen]

21 hours ago, patrykj26 said:

Hello,

 

I have a Specna arms SA-BO3 and my piston seems to jam in the outward position (when the spring is fully compressed) only way i found to fix my problem temporarily is to loosen the bolt that holds the spring in. not ideal as its now less powerful. any suggestions. i have stripped and rebuilt the gearbox nothing looked damaged. piston moves freely in the cylinder. gun jams when in fully auto or quick single fire.

It might be that the battery that you are using is not butch enough for the job; what battery are you using?

[patrykj26]

7.4v 2600mAh 20c LiPo

[Colin Allen]

21 hours ago, patrykj26 said:

7.4v 2600mAh 20c LiPo

That should be chunky enough.

[Skara]

Stock piston?

I'd check for damage around the back of the piston body, i suspect what happens is that the piston jams itself onto the spring guide, or that the spring somehow stretches itself over the spring guide and subsequently jams the piston.

 

I've seen this happen a couple of times and already on Dboys guns (same exact internals as specna, just red plastics instead of blue)..

 

A few different ways to solve it, some involve a bit more labour and parts changes but permanently removes the issue (look up short stroking).

[patrykj26]

yes everything's stock. when i took it apart last time i did see some light marking on the piston as you've said. what would you suggest i should do to prevent that from happening to the new one if i replace it?