20fps loss on full auto, and possible low rps

[Mr0161]

Hi all,

Currently have an issue, where in single fire, I'm getting around 290fps on 0.25s, but on full auto it drops to 270fps and 28 RPS which seems a bit low for my setup.

11.1V 1450mAH 25C Stock Tube LiPO

G&G V2 gearbox

Perun Hybrid V2

XT 200mm Barrel

ZCI Rotary Plastic Hop Up

Maple Leaf Macaron 60° with Omega nub

13:1 SHS Gears (Short stroked 2 off of pickup side)

Warhead Base 27k

ASG Ultimate Nozzle 21.2mm

SHS / XT Cylinder and Piston Head Aluminium V2/V3 (Silent)

XT M110 Spring

FPS Softair Zero-Shock Carbon Fibre Piston with Steel Tooth Rack

KoA 230% Tappet Plate Spring

FPS Softair Carbon Fibre Reinforced Tappet Plate for Version 2 Gearboxes (Trimmed by 6mm)

SHS Delayer Chip (Left side of it filed flat)

Any idea what's causing this?

I've already checked compression and the shimming, and both are fine.

Could it possible be PME, or maybe I've trimmed the tappet plate too short or some other weird tappet timing issue?

Cheers.
 

 

[Sewdhull]

if you are getting 28rps that seems ok, you are probably being limited by the battery.

I unsure that you need all the things you have in place. If you had PME you'd be hearing the gun chewing itself to pieces.

If you are losing fps on auto its, to be expected to a degree, but you might be pulling the tappet plate back early... you'd need to look at how it cycled out of the gun manually

 

[Mr0161]

Okay that's good then!

Lol true, I was threw into the deep end when it comes to teching, bought my first "upgraded" lemon of gun a couple of months ago and have replaced everything bar the mosfet.

What would be the best way of slowing down the pulling back of the tappet plate? Maybe I could try and run it without the delayer? Or maybe I can shave the tappet plate down slightly like in the pic attached? Guessing this will cause issues with the nozzle and feeding though.

View attachment 135791

 

[Mr0161]

Done a bit of testing and threw in an M115 spring which seems to have sorted it!!

Running a bit spicy now though, 350fps on 0.25s lol

Would it be better to chop the spring a bit, or short stroke the sector gear a few more teeth?

 

[Sewdhull]

Take off one of the spring bearings if you have 2. There's no reason to have 2, and you will reduce the preload by doing it.

Either you've assembled the gun better this time or the springs are not rated correctly. You shouldn't be seeing that much difference between the springs altho the rps should be lower and may have addressed the timing issue if there was one.

Unless you are using a known set of parts that works in your gun specifically, changing one thing at a time is advised.

You wouldn't normally need a delayer unless you were getting feeding issues.  

 

[Mr0161]

Cheers for the suggestions, finally got it perfect after a bit more messing around. Looks like that M110 was dodgy, as I tried it in a mates gun and it was about similar to a M100.

Weirdly, swapping from the bearing spring guide to a standard plain one only dropped the FPS by around 2-3, so put the bearing one back in, and now I'm running the M115 spring, with 2.5 coils chopped off, and took another tooth off the pickup side, so now it's at 305fps on 0.25s, whether on semi or full auto at 29 rps and doesn't miss a beat!

 

[Pseudotectonic]

pretty sure it was PME