Rcommend piston setup that can take some serious punishment

Adolf Hamster

Adolf Hamster

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anyone reccommend a piston setup that can take some serious punishment.

this is totally unrelated to the ak and m4's ludicrous fire rates, no they didn't both die within 3 seconds of switching to full auto, this is fake news, don't believe everything you see in mainstream media sheeple.....

also anyone know if the marui 226 barrel fits we?

 
Adolf Hamster said:
anyone reccommend a piston setup that can take some serious punishment.

this is totally unrelated to the ak and m4's ludicrous fire rates, no they didn't both die within 3 seconds of switching to full auto, this is fake news, don't believe everything you see in mainstream media sheeple.....

also anyone know if the marui 226 barrel fits we?
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SHS std blue full rack piston is the one most go for

alas it can bind slightly in a number of boxes (not G&G's)

If it is very slight binding, then sand the rails in box

If it is very tight then the cyma full rack piston is less thick

but is quite sloppy in boxes like G&G's

If your box has a rear inspection window then imho avoid the lightened ones

tbh safe bet is the std blue shs metal rack piston - no holes/swiss stuff

Do not bother with the 3 or 7 metal teeth SHS pistons

they look like the perfect pistons - but the plastic teeth are DairyLea

the soft plastic teeth strip quite quickly and are a waste of time & money

 
Sitting Duck said:
SHS std blue full rack piston is the one most go for

alas it can bind slightly in a number of boxes (not G&G's)

If it is very slight binding, then sand the rails in box

If it is very tight then the cyma full rack piston is less thick

but is quite sloppy in boxes like G&G's

If your box has a rear inspection window then imho avoid the lightened ones

tbh safe bet is the std blue shs metal rack piston - no holes/swiss stuff

Do not bother with the 3 or 7 metal teeth SHS pistons

they look like the perfect pistons - but the plastic teeth are DairyLea

the soft plastic teeth strip quite quickly and are a waste of time & money
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tis a windowed box and i'm not concerned about lightness, only the ability to withstand maximum high speed punishment.

the m4 has an all steel tooth piston which is what it just ate, twas blue but darker than shs's.

cant recall what the m4 box is but the ak is jg

 
I'm pretty sure in both cases it was the rate of fire did it, the jg was running the stock all plastic piston and i was expecting it to fail.

The m4 on the other hand has been a result of my quest for trigger response, it's asg's "high torque" motor with the neodynium magnets but despite being supposedly for torque rather than speed it spits out bb's at an alarming rate.

In both cases i'm happy with the rate of fire (hell the m4 i'd rather be a bit slower even) so i dont mind a heavier piston dropping the rof as long as it can survive.

I'll crack the boxes tomorrow and see if anything else has died but i'm pretty confident it's primarily schredded pistons i'm looking at.

 
Sitting Duck said:
Piston weight has nowt to do with rof - a lighter piston may return quicker to avoid PME

But the cycling speed will be the same as determined by gear ratio, motor, voltage etc....

Generally speaking a std setup eg: full(ish) stroke, 350fps you are looking at aprox 20~25rps

(The term twenties is plenty)

Once you approach 25rps you will get serious overspin even double firing on single

Gun is talking to you, if you push it much faster on a std UK gun you will run risk of PME

Unless you run a m120 Short Stroke setup PME will take place at 25~30rps I reckon

Hence why certain TM High Cycle guns were Short Stroked to achieve snappy 320fps

If you drop the bearings inside the piston that will save you about 4gms

which you would be hard pushed to swiss cheese that much weight off piston

drop bearings, save about 3gms, pom piston head and you should be about 22~24gms metal rack

you don't want it ultra light coz you arent pushing 50rps DSG

plus an ultra light piston is inefficient in generating compression

Most important thing is to ensure piston doesn't bind - this slows piston speed (not good)

(plus increased resistance in cycling - but slow dragging return will increase PME risk)

Then keep the speed at 20rps or just over unless you have done your homework
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i haven't measured it but to ear it sounds like it's in the 1800-2000rpm range so that's around 30 rps.

i'd kind of hoped by going for torque the motor would naturally peak itself and limit the rof, but sadly it's much better than that. the etu/motor combo has some insane braking to it so no double spinning on semi but that motor doesn't seem to care what the gearbox says.

the aim of this gun is trigger response and good semi performance, so i'd be more inclined to disable fully auto than short stroke it, although it's nice to have the ability to spray and pray as a backup.

i'm about to crack it open here so i'll report back on what else has been shredded.

 
welp, post mortem is complete, the existing piston was all steel tooth except the one that counted- the first one.

looks like it just couldn't take the strain.

i'll get a pair of the shs 15 tooth ones and see how that goes, if it can survive in the m4 it'll defo survive the ak.

rest of the gearbox looks fine. i'll hold off on the ak until they arrive as i'm 99% certain it'll be the same story.

 
the gun is old and it was nowhere near stock when i got it (had been upgraded a lot then abused within an inch of its life). the motor it came with was on its last legs.

the etu is functioning fine now after much fiddling, it's not really the problem. although sadly i can't use it to tune down the rof.

it was the rearmost "tooth" that forms the back of the piston that went, so the rack did nothing.

it's primarily a pseudo dmr gun so semi 90% of the time, but it's nice being able to dump the mag if required. but i'd sooner accept the loss of full auto before messing with short stroking it. it was fine in semi for a good while it was definately the full auto just killed it.

 
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Sitting Duck said:
Blah blah blah....

or it will try to split the rear of piston at a moulding seam right at the back/pickup tooth area

Thought I had a pic of a shs piston splitting at the pickup seam as the rack tried to get ripped out

That was a m120 13:1 SHS HT running on a bastid 11.1v 33c 1300 mah packed with plutonium I think

the LiPo is f*cked, 1 cell is 3.9, 4.0 & 4.1v - never balances it is w@nked tiny thing I got in bundle of bits

But somehow it contains so much more wallop than usual 25c Zippy 7.4v & 11.1v's 2200 mah

That f*cking battery has wrecked more guns than I dare use it now

Unless it is a really sluggish 28tpa std gear plodding gun

The last gun it wrecked m120 SS 3 teeth 13:1 SHS HT was producing about 23~24rps on 7.4v Zippy 25c

Really nice responsive build - so I thought let's see just good my build is... (not such a wise idea I later learnt)

when jumping to 11.1v it is a bit more than 50% as the gun is cycling already

so the boost imho is about 55%, so a zippy 11.1v 25c was cycling about 37rps and wow that is insane

getting a lot more overspin - that should have triggered alarm bells but nope I thought it would be ok

plugged that little bastid in and OMG that is much quicker - oooh f*ck that don't sound right

yup - it wrecked it before I could chrono it FFS wot a nob

yeah I was not a happy bunny after doing all that homework and planning and extra crap etc....

F*CK IT, I'VE HAD ENOUGH OF WRECKING CRAP TAKING THE PI$$ & PUSHING STUFF CLOSE TO LIMITS

Moral of the story - even if you do all the extra work

it will still wreck if you sail too close to the wind taking the pi$$

Then you will be mega pi$$ed - so plan it well and dial back the pi$$ taking or extra juice/rps
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i get what you're saying, although i'd rather get it working again and know i just have to be careful if going full auto, if it kills the shs piston then i guess i've a decent reason to run burst fire.

 
mate, you offered a wedge of help to him, but he needed a whole topic for his question, not a quick answer! ?

 
Moved from Quick Questions & SImple answers; this was a lengthy topic in its own right.

 
I was TRYING to keep it brief believe it or not

(but as usual once I get started...... )

Knew or highly suspected stuff was running too quickly

coz well ergh I have done that loads of times, I'm sure many on here have also gone nutz

Off topic a bit, Duck Jnr gets his go faster motor

Tells him this old fart wrecked his beefy go faster motor by taking the pi$$ showing off

(blew one gearbox & the diff TWICE doing burnouts and generally being a younger nob)

Yup Jnr's motor has loads of warning lights like a xmas tree again & again costing loads

confides to mum:

" I MIGHT have driven it a BIT madly a FEW times.... "

rough translation - He has been a nob and driven it LOADS like a mad w@nker despite the advice

After the last time of building a 13:1 SS 3t m120 SHS HT running sweet @ 24rps

then pushes it near 37/38 on 11.1v, only to to put a mofo bastid 11.1v on it pushing at say 40+

then wrecked it after all that work - this makes moi a bigger older f*cking stupid w@nker

Twenties is plenty and call it a day now

If I chose to build for 30~35rps (not often now)

I'll still run on 7.4v at low twenties coz well it's cheaper and well below the limit/margins to last longer

Regarding pistons - SHS is a good go to piston as said - just std reg blue SHS metal rack

can be a smidge tight but usually just a mild mod to glide sweetly but not sloppy as f*ck

Cyma's are looser, but they are a smidge shorter in length so no chance of bottoming out on full stroke

Bare piston weights:

SHS std blue weighs 15.75gms aprox

Cyma weighs 16.1gms

So there is nowt in it really weight wise, just use which one fits/works best

No real need to swiss cheese them coz they aren't that heavy like some 18~19gms pistons I got

(you don't save THAT much weight even if you go nutz considering time cleaning it all up etc.. maybe 2~3gms)

drop bearing or piston spacer instead is quicker easier if fps doesn't suffer too much on spring compression

select which piston will work best in ya box

(not too tight/binding & not too loose/sloppy)

Yes after checking for 2nd tooth removal & reduce 3rd tooth a bit, the rack should be glued into place

not superglue, epoxy for the rack, should use epoxy for rack and bushings if poss

(superglue on bearings is ok at a push, but racks should be epoxy'd in if doing it right)

Whoa - getting carried away (again)

 
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wow, just goes to show i rely too much on the alerts system didn't realise this had been threadified  :D

shs pistons are in, time will tell if it survives. i'm debating putting the m4 to 3rnd burst for the sake of saving hassle and reserving the ak/mg for when people need a hosing to convince them they've been hit.

also, still in my defence, a stock jg ak does not count as a speed build!

although the m4 seems to have turned out that way it wasn't my intention, it's my bushlurking gun  :P

also it'd be nice to have at least 1 gun with decent semi auto response, the f2000 is sketchy in semi, the ak double fires and the mg doesn't understand :P

 
Sounds like your RIFs need attitude adjustments mate nor more parts!? :D

 
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