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Tuc

Yugo Gas Tube Piston

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I pulled my gas tube piston out cause the SKS isn't shooting semi-auto (the gas tube is cut on, down and to the right) and I noticed that the piston looks nice and shinny except for the last 3/4" on the small end. it is brown and is about 0.008"-0.010" smaller than the rest of the piston shaft. is this normal or do I need to replace the piston? I figured the reason for it not cycling back is gas escaping. Any info would be great, Thanks!

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I am not sure about the size but the piston on my Yugo is black/brown the last 1/2" or so. The leakage problem would be more to do with the actual piston than the black/brown end of it.

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do you know how to fix the leak? I have heard a bunch of different fixes. does yours do the same thing?

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I had problems with mine cycling once. The 'pin' on top of the gas tube socket (that allows you to lift your grenade sight on Yugos) has to be closed and to the right or gases will escape and the rifle won't cycle. I thought I had major problems with my rifle until I figured this out. Was yours closed?

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I suggest checking for gas leaking from the joint where the tube connects to the valve. (That's where Yugos typically have problems.) The next time you go to the range, bring some talcum powder and sprinke a bunch of it around the valve area. Fire a round and look to see if any was blown away. (Of course, make sure to wear eye protection to keep it from being blown back in your eyes!)

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I had problems with mine cycling once.  The 'pin' on top of the gas tube socket (that allows you to lift your grenade sight on Yugos) has to be closed and to the right or gases will escape and the rifle won't cycle.  I thought I had major problems with my rifle until I figured this out.  Was yours closed?

Yea mine is closed. I have had this one for a couple of years now. when I first got it I thought it was broken. so I put it in the closet until the last few weeks. I read where a guy said to take a piece of 22 gage galivized steel wire and make a metal washer to put in the groove. he said it works for him. does that seem right or should I replace the tube and piston?

Thanks All!!

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Use a rubber oring the size of the shut off valve lip makes it a little hard to get the gas tube back on. I took the valve to the hardware store and matched a thin rubber oring and had no problems since. ok>

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Use a rubber oring the size of the shut off valve lip makes it a little hard to get the gas tube back on. I took the valve to the hardware store and matched a thin rubber oring and had no problems since. ok>

so the rubber o-ring lasts thru the heat and compression?

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A regular rubber O-ring will melt. You'd have to get one that will withstand the heat, one for use in a hydraulic pump rather than just to seal water in a hose.

However, that might not be your problem. You have the gas valve in the correct position, but are the gas ports fouled with carbon crap? Use the tool in your cleaning kit or a pipe cleaner to clean the gas ports in the valve and the barrel. Also check your piston extension rod to make sure its not fouled.

I don't think the smal end of the piston has much to do with the gas seal.

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A regular rubber O-ring will melt.  You'd have to get one that will withstand the heat, one for use in a hydraulic pump rather than just to seal water in a hose.

However, that might not be your problem.  You have the gas valve in the correct position, but are the gas ports fouled with carbon crap?  Use the tool in your cleaning kit or a pipe cleaner to clean the gas ports in the valve and the barrel.  Also check your piston extension rod to make sure its not fouled.

I don't think the smal end of the piston has much to do with the gas seal.

I will look at those tonight when I get home. I just don't know too much about the Yugo SKS.

Thanks Patski

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used it for 1 year now and havent changed it yet the use them on auto airconditioners and they last years under 200psi with more heat than a sks will make. B{

Edited by nientok

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is it the nylon o-rings??

Edited by Tuc

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Never thought of that they should even work better I will give it a try on mine. Make shure you have the valve to the right and check the hole inside and see if it's clear and make sure you have the gas tube real clean and don't oil it that makes deposits worse I have fired over 500 rounds mine and still shooting. ok>

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hmm.. i need to try this. Went to the range today and was forced to play bolt action today. Sounds like an easy fix though. :)

- Brian

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Never thought of that they should even work better I will give it a try on mine. Make shure you have the valve to the right and check the hole inside and see if it's clear and make sure you have the gas tube real clean and don't oil it that makes deposits worse I have fired over 500 rounds mine and still shooting. ok>

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So don't oil the gas tube at all then right?

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Here is a great video on cleaning sks it explains how oil will make gas tube malfunction sks cleaning video watch cleaning video ok>

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cool Thanks!

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