V2 Gearbox Not Cycling Fully
 

Ive tinkered with this M4 for a while now, and have taken it to a few other gundocs as well and none of us can figure it out.

im using a fully charged 8.4 1800ma with a stock gearbox and a stock spring.
After pulling the trigger, the gearbox cycles 90% of the way back and locks up.
The gun worked perfectly fine before, no damage to it. The gears seem to work flawlessly, as when used without the piston, the gears cycle perfectly, and the nozzel moves back and forth normally. Only with the piston inside, it refuses to cycle.

does anyone have any ideas?

Has anything been done to the piston? Sounds like it's not seating as far in as before (making it "longer"), causing the spring to bottom out before the last tooth on the sector gear can unmesh from the piston's teeth.

Have you simply tried another piston?

There's your problem ;)

I had no choice, I had a cylinder head blowout and i replaced the cylinder head.
If the cylinder head was the issue, it would be a sealant issue not a cycling issue.
The piston hasnt been touched, and everything except the cylinder head and tappet is origional.
The tappet has been ruled out already due to the fact that it cycles fine when the piston isnt inside.

If the cylinder head isn't the same dimensions as the previous one, it might cause the piston to sit a bit further back than normal, causing exactly what I outlined above, sector gear grabbing the second tooth on the piston instead of the first tooth. I've even come across a couple pistons that are slightly longer than stock, which had caused the mechbox to either size up from the piston, or the teeth on the piston getting sheared off and chewed to shit.

i see, it makes sense now. Ill take it apart and look at it again. thx

Cool, good luck. Hopefully it's a quick fix.

yeahh.. probably the spring is not sitting all the way inside the piston body. Maybe it's too long or there is stuff inside the piston body..

Anyhow.. i just figured out.. maybe when you replace your cylinder head, the piston was pushed back a single tooth.. so the first tooth of the sector gear is eating the 2nd tooth of the piston body... in that case.. there would be a miss match of gears. Got my point?

I had the same problem with my v.2 gearbox in G3SAS. I charged the battery within 1,5hours and it didn't cycle completly. It was because I charged too much my battery and like I burnt it. So it was like it lost some power, not enough power to cycle at 100% and beat the pressure inside. It's why with the piston out it's cycling completely.

Hope that helps. Try with another battery if you could.