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$alinas

Piston Head O-ring Replacement

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I purchased a used bore up set from a buddy of mine and the piston head o-ring has lost compression when testing by hand.. (pushing piston/head back and forth in the cylinder while covering cylinder head tube) It does not hold any air while in motion. I've thought that this might be an o-ring problem and would like to replace. Has anyone ever tried to find one at a local hardware store? I'd hate to have to go and buy a new Piston head just to test.

 

Thx

Edited by $alinas

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I would try lubing it first (as previously suggested).

 

I tried #14 O rings (available at Home Depot, Lowes, etc). They appeared to seal properly, but produced inconsistant velocities after the gearbox was reassembled.

 

You can buy an O ring for a couple of bucks:

http://www.airsoftgi.com/product_info.php?...roducts_id=1815

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I would try lubing it first (as previously suggested).

 

I tried #14 O rings (available at Home Depot, Lowes, etc). They appeared to seal properly, but produced inconsistant velocities after the gearbox was reassembled.

 

You can buy an O ring for a couple of bucks:

http://www.airsoftgi.com/product_info.php?...roducts_id=1815

 

Ugh, Sold Out at airsoftgi :)

 

Ok, I tried the lube job and no luck.. Also went to Home Depot and found the o-ring you mentioned but they are slightly smaller than the bore up.. So, I will look through a few airsoft sites for a replacement.. if anyone comes across any, let me know.

 

thx!!

Edited by $alinas

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when your testing it by hand there shouldnt be very much compression. because the spring pushes your piston a lot faster than your hand can. the little holes fill up with air and puch the o ring out which makes compression. so I would put the gear box togather first and test it before you get a new o ring

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Guest Whorify

actually no, good cylinder compression would be zero compression loss with a hands test. unfortunately boreup kits are suppose to have small Orings, they're suppose to be used with springs rated over 430 fps and higher. but to use it in a lower fps system, you'd need to increase the size of the Oring. try local hardware stores and bring in the boreup kit with you and test fit the Orings on site. a good hardware store (unlike homiedepot) will help serve you. look into metric sized Orings.

 

Trichrome also suggested in previous boreup threads that he used a stretching method. stretching the Oring over the cylinder and leaving it that way for a day.

Edited by Whorify

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Guest TriChrome
Trichrome also suggested in previous boreup threads that he used a stretching method. stretching the Oring over the cylinder and leaving it that way for a day.

I use Systema bore-up kits in all my guns (basically because I've never broken one in over 3 years of hard tuning). My guns shoot from 350 FPS to 450 FPS. The o-rings all needed to be stretched; and any time I open up the gearbox for tuning I stretch them again. I believe the myth about bore-up kits not working on lower powered guns is attributed to this.

 

Anyway, take your bore-up o-ring you got with the kit and put it over the end of the cylinder. Take a lighter and heat the o-ring; should take about 5 seconds (while rotating the cylinder in your hand) to do the entire thing. Let it cool for a minute or so, and do it another two times. Let it cool for 5 minutes before installing on the gun. That will stretch it perfectly, and give you a good seal.

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I have taken a stock ECHO 1 gearbox apart and re-assembled it with the only change being a stretched and heated O-Ring (as Tri-Chrome mentioned above) and the difference in velocity was 15 fps. and that was on stock components, nothing else in the gun changed.

 

Stretching the O-ring works. But get it nice and lubed.

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I use Systema bore-up kits in all my guns (basically because I've never broken one in over 3 years of hard tuning). My guns shoot from 350 FPS to 450 FPS. The o-rings all needed to be stretched; and any time I open up the gearbox for tuning I stretch them again. I believe the myth about bore-up kits not working on lower powered guns is attributed to this.

 

Anyway, take your bore-up o-ring you got with the kit and put it over the end of the cylinder. Take a lighter and heat the o-ring; should take about 5 seconds (while rotating the cylinder in your hand) to do the entire thing. Let it cool for a minute or so, and do it another two times. Let it cool for 5 minutes before installing on the gun. That will stretch it perfectly, and give you a good seal.

wait so you attach the oring like it would normally be and then you basically shrink it so that it is flush with the piston head?

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wait so you attach the oring like it would normally be and then you basically shrink it so that it is flush with the piston head?

 

 

Take the Oring and put around the actual cylinder NOT the piston head. (eg. http://www.airsoftgi.com/images/imagecache...ap-cylinder.jpg ) This will help strectch the O Ring bigger. You can heat it by lighter, boiling water, hair dryer etc. Hairdryer and boiling water seems safer to me. Then let it cool to "set" the Oring to it's new expanded size.

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Take the Oring and put around the actual cylinder NOT the piston head. (eg. http://www.airsoftgi.com/images/imagecache...ap-cylinder.jpg ) This will help strectch the O Ring bigger. You can heat it by lighter, boiling water, hair dryer etc. Hairdryer and boiling water seems safer to me. Then let it cool to "set" the Oring to it's new expanded size.

oh gotcha :a-thumbsup:

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The correct cylinder head o-ring size for Marui compatible aeg is 24 mm 19 x 24 x 2.5 o-ring . material nitrile, viton or sillicone for low temperature.


#14 o-ring is 15/16 inch 23.81 mm so you lose .19 mm of material.

Also stretching o-ring and heating it will not help it will revert to it size after some time.

Edited by nekro-christ

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