High ROF ate my piston, need advice.

[The Keeper of Secrets]

Ok,

I have run my stock G&P SPR for a while (year-ish, seen fequent use) without problems, with a ROF a fair bit above average. Recently I put in a systema highspeed motor, which created a very high ROF, which it handled fine. this was doing 300fps.

Today, whilst firing, the piston broke. Dang. I assumed it was because of pre-engagement (sector gear re-engaging the piston before the piston has moved fully forward).

I opened it up to find the broken piston, and all else absolutely fine and working well. I put in a new pistoin (this about half an hour ago), and an M100 spring, which I hope to allow the piston to return quicker and so stop the pre-engagement that killed the original piston. I also cleaned and regresed it; there was a lot of dirt and grub in it indeed.

My questions are:

Am I safe doing this, or is the ROF simply going to eat through piston after piston?
Is there anything I can do to prevent the pre-engagement?
Is it just a problem for all systema highspeed users?

The condition of the old piston, showing the broken tooth, and stipped teeth that confirm pre-engagement:





All help is appreciated.

[johnnyj]

Re: High ROF ate my piston, need advice.

nvm... not thinking

[strettman]

Re: High ROF ate my piston, need advice.

this happend to my mates rubbish FN2000 after about 10-20mags, if you get the metal teeth pistons it will help alot, i can't give you any more info really as i do not use a systema motor....... yet

[The Keeper of Secrets]

Re: High ROF ate my piston, need advice.

I stay away from metal pistons, and would advise you to do the same. A piston is a mechanical version of a fuse, it will go as oppose to your gearset. I'd rather the £10 piston was eaten in this case, as oppose to a £50 gearset.

I'm thinking of filing down the 2nd and 3rd teeth.

[mamba]

Re: High ROF ate my piston, need advice.

I'm thinking of filing down the 2nd and 3rd teeth.[/QUOTE]

Yup! this needs to be done on high speed set up and the proper AOE of the piston tooth in relation to the sector gear. It can be done two different ways, by shimming the piston head or customizing some cylinder head pads. I have experience this problems before but now it is a thing of the past. I have just stick to 25 ROF, more than that won't mean a thing, the piston can't cope for the high revving gears.

[mamba]

Re: High ROF ate my piston, need advice.

I'm thinking of filing down the 2nd and 3rd teeth.

Yup! this needs to be done on high speed set up and the proper AOE of the piston tooth in relation to the sector gear. It can be done two different ways, by shimming the piston head or customizing some cylinder head pads. I have experience this problems before but now it is a thing of the past. I have just stick to 25 ROF, more than that won't mean a thing, the piston can't cope for the high revving gears.[/QUOTE]

My 2 G&P pistons a couple of years ago, High ROF set up at 350 fps , >30 on 11.1 25C lipoly OTB, no mods. This happens on pre engagement and poor AOE.




G&P ROF OTB stock unopened with 9.6V >2000mah, I can add 5 more just tinkering with the GB.

[Jetpilot]

Re: High ROF ate my piston, need advice.

G&P pistons are shockingly week, rof has nothing to do with taking the back end of them, there just sh*t! I would recommend using a prometheus hard piston and as mentioned remove the 2nd and 3rd tooth.

The extend your piston is damaged though shows signs of massive pre engagement, this is most likely down to the fact your spring is not returning the piston to rest quick enough, a m100 is very weak, i would suggest at least a 110 -120.

Pistons are the weak point and will break due to the higher tolerances needed with a higher than standard rate of fire.

Hope this helps and if it happens again give me a pm for further help or advise.

And your right, stay away from aluminium pistons, not only do you run the risk of doing a gear they also slow down rof due to weighing loads.

[dope_on_a_rope]

Re: High ROF ate my piston, need advice.

Correct the angle of engagement as Mamba said. Remove the second tooth. If you feel you have to, slightly file down the 3rd, but don't remove it completely.

It's hard to tell if that piston is shredded because of poor AOE, or because of pre-engagement. The damage certainly points to pre-engagement, so check your barrel. Keep it clean. If a BB is slowed down by grit in the barrel, it can cause a lockup that'll slow the piston in it's return. That's when pre-engagement happens.

As for a new piston. The G&P one should be fine. TM would be great as well. I seem to remember SniperJesus saying ICS pistons were pretty good in high ROF set ups. They're made of a slightly different material, allowing some movement to counter for the poor angle of engagement. But if you're fixing it anyway, no need to worry I guess. Prommy ones seem fairly expencive for this aplication.

You shouldn't need to short stroke this piston. That'll only be a concern when you're running around 30rd/s off an m100. You could swiss cheese the piston to reduce weight. It'll travel faster. I don't see that making a massive difference to be honest.

[Gaffa]

Re: High ROF ate my piston, need advice.

May I suggest (to everyone) the Element red piston - I know it may be cheep, and only polycarbonate, but there are so many reviews on the net that say its very good.

Personally, never experienced any problems with them.

Regards, Matt.

[mamba]

Re: High ROF ate my piston, need advice.

May I suggest (to everyone) the Element red piston - I know it may be cheep, and only polycarbonate, but there are so many reviews on the net that say its very good.

Personally, never experienced any problems with them.

Regards, Matt.

Sorry! but we have shredded a lot, poor quality

Normal cylinder head pads.


Our customize cylinder head pads.


Perfect AOE with shave 2nd and 3rd tooth of Deep fire PB. I have used 10 bags of ICS .2 5-6 months of conservative use (1-2 second burst fire, no more 5 to infinite seconds burst fire.....hehehehehe). Average of 2 bags per game day. Set up 350 fps at 25 ROF on a standard G&P GB and G&P 9.6V 2200 Mah. It's still looks great!


Pictures courtesy of our Tech Guru Shredder!

[Jetpilot]

Re: High ROF ate my piston, need advice.

You shouldn't need to short stroke this piston.

Do you mean short stroke the gears?

[Jetpilot]

Re: High ROF ate my piston, need advice.

Mamba, what are you using for your spacing pads. I went down the sorbothane route and very happy with results.

[mamba]

Re: High ROF ate my piston, need advice.

Mamba, what are you using for your spacing pads. I went down the sorbothane route and very happy with results.

We have tested the sorbo, 1st gen (Ars sorbo pads....but they are going to send me there latest creation direct from Japan) but it cracks prematurely, specially on this kind of freezing weather, we have used a combination of sorbo and some reinforcements which I don't know, it's our Gurus little secret.....hehehehehehe!

[dope_on_a_rope]

Re: High ROF ate my piston, need advice.

I mean short stroke the piston. The gears don't have a stroke, they have a revolution. Although in effect by correcting the AOE, you are shortening the stroke of the piston, that's not what I mean either. Any good airsoft technician knows what I mean by, "short stroke the piston."

That looks a pretty neat setup Mamba. I'm also interested in the material choice for the spacer/pad. How did you attach them too?

[Jetpilot]

Re: High ROF ate my piston, need advice.

Just curious buddy, its all advise and learning in this game. Surprised your sorbo cracked as its very subtle. Thanks for the reply.