Cyma AKSU - RPS and magazine "issue"

[Skara]

Tech question for the AK gods:

 

 

Cyma shell and motor cage.

18:1 gears, 4 teeth short stroked from the pickup side.

FPS/guarder/Slong compression parts.

Warhead 36k, Perun Hybrid, shs m100 spring.

99.something m/s on 0.2s which is on the money for my limit.

 

Here come the questions:

 

7.4v 1450mAh 30c nets me 14 RPS.

11.1v 1200mAh 15c nets me 20/21.

 

Seems a bit low? 65% efficiency?

Little drag on the gears, no drag on piston nor tappet plate. Motor height is set.

 

 

 

Also, have you ever experienced having to pull mags towards the gearbox to make them feed?

All my mags have 2ish millimetres of play at the back, I was thinking of either replacing the mag release or bodging a spacer for it.

[Pseudotectonic]

Perun ROF reduction settings?

 

If not, could be shimming related

 

Bearing bushings or solid bushings?

[Sewdhull]

The warheads are 36k at 11.1v

 

What perun settings are you using?

[Skara]

No rof reduction, 20% ab, then irrelevant stuff like trigger sensitivity and no battery warning (warhead takes care of that), no precocking nor any other bollocks going on.

 

I'm using the stock cyma solid bushings (I believe they're 7mm), that I do not really like but currently I am just testing things out, I will replace them with better quality ones once I have everything sorted (along with a set of 13:1s).

Also in the gearbox there are currently 3 shims because that's all the bushings allow me to use. Overall it's decently shimmed with very little drag

 

It is a couple of BBs per second faster than a bone stock gun, I say it's okay considering that a stock motor is 30ish-k RPM on 11.1s.

[Pseudotectonic]

Only 3 shims? Sounds suspicious...

 

Solid bushings actually not a problem

 

But 3 shims sounds too few to have

[Sewdhull]

Did the cylinder move freely. Different gears can press unduly hard upwards on the rack and create drag?

 

I'm having that issue right now on my SRC G36.

Are you confident the bushings are pressed in sufficiently?

Edited February 17 by Sewdhull

[Skara]

Yeah unfortunately I didn't take a picture when I took the box apart, all the bushings stick out inside the gearbox by 1/1.5 millimeters. No side to side movement, they're solid in there.

 

But anyway, I think I managed to fix the mag issue, I was using the E&L magwell spacer because I thought it was better than the cyma one, big mistake.

Cyma spacer in, went through a full cyma flash mag without skipping a beat.

 

So next step is to play with it (tomorrow) and then take it apart to replace bushings and maybe throw a set of 13:1s in there.

[Lozart]

Turn off the active brake.

[Skara]

4 minutes ago, Lozart said:

Turn off the active brake.

Nope, massive over spin if I do.