Author Topic: Yugo gas tube (Read 11845 times)

SmittySKS · « **on:** October 22, 2016, 01:38:24 AM »

So my new to me Yugo wont cycle. I believe the gas tube (not original to rifle) is pretty much shot. Looking at it theres alot of pitting and the piston is doesn't seal in the tube. I see that the yugo gas tube is not the same as other models. Can anyone tell me what the difference is? I really don't want to bubba it up if I don't have to. Also, can anyone tell me if the piston should fit snug between the valve and the piston extension or should there be a gap?

Thanks all

armedhippie · « **Reply #1 on:** October 22, 2016, 02:10:31 AM »

Hiya Smitty! So...the number 1 question asked about Yugo's, involves cycling issues. So if you know this 1 allready no worries, but we gotta ask. What position is your gas valve in? Is the push button up or down to the side? Also does it fire the 1st round you manually charge?

Welcome man, Hope we can help

carls sks · « **Reply #2 on:** October 22, 2016, 09:14:01 AM »

you could also take a look on u/tube, might find some info. I have learned a lot from vids there.

Justin Hell · « **Reply #3 on:** October 22, 2016, 10:50:45 AM »

The first time I fired a Yugo...it didn't cycle. Chalk that up to the valve being in the wrong position.

I wouldn't think the gas tube being a bit pitted would be the problem. Most of the cycling issues are valve related...if the piston moves freely for the first two inches of movement, it should be capable of doing it's part. There should be plenty of gases to cycle it. When shooting it, have someone watch to see if any gases are visible escaping from the breathing holes in the tube. If none are seen, also check to see if any residue is left in their vicinity. Those holes are to prevent pressure building up in the tube behind the head of the piston within the tube...and don't expect it to be totally air tight...it should be more like an engine piston that is close to needing new rings. If it is too excessive, residue should be seen after several rounds around those holes...which should be blasting a lot of gasses out if the tube/piston are the problem.

You might also check the operating rod inside the rear sight housing to ensure it is not stuck, this is what the piston is trying to move. If it is frozen, all the gases will have no choice but to push the bullet harder and not cycle the rifle...and probably end up bending the piston over time.

All that being said, if the valve itself or it's ring/gasket are badly corroded the proper amount of gas can't get by and you will get the same result. This often can be fixed with a little MacGuyver ingenuity and a paper clip.

You didn't say whether it was giving any indication of partial cycling, like the op rod poking out and sticking, holding the bolt open, or partial extraction...so I am assuming zero indication of cycling at all.

hope that helps...

Loose}{Cannon · « **Reply #4 on:** October 22, 2016, 10:54:05 AM »

Most the time, the issue with yugos is the gas valve being corroded and gas escaping from around it and out of the button area and where the gastube slides over the end of the valve.

Can you remove the valve and take pics of its outside, and perhaps the inside rim of the tube?

Murray from Murray's Gunsmithing (vender here) makes a new gas valve that is over sized to correct this very issue.

SmittySKS · « **Reply #5 on:** October 22, 2016, 02:13:43 PM »

Thanks guys for the responses...I guess I'm kinda taking a shotgun approach to this problem.
New SS gas valve on the way from Murray's. Old one looks OK to me but....WTH.

Also a new bubba gas tube assm from Tapco. I hate the look! No one makes something better???
I've watched a bunch of Utubes on this problem and the one that really lead me to believe the gas tube is shot was one that showed if you put your finger over the top of the GT with the piston in the tube and turned it the tube straight up, the piston should drag from suction. Mine just drops. I tried to get a measurement on the ID of the tube but its so eroded that I couldn't get a good #.. Does anyone know if the piston should have .025 gap between the valve and the operating rod?
I only shot 9 rounds and my buddy said he thought the bolt was only going back an inch so I stopped firing it.

Loose}{Cannon · « **Reply #6 on:** October 22, 2016, 02:29:54 PM »

Quote

Does anyone know if the piston should have .025 gap between the valve and the operating rod

Not sure what/where you are referencing here...

Quote

the piston should drag from suction

Not a good test in my opinion, but a really corroded tube having too large of a diameter isnt ideal.

The new valve is over sized and will close up the gaps inside the gas block where it resides, and possibly the fitment to the tube. I would just wait and see how it acts with the new valve, and go from there.

SmittySKS · « **Reply #7 on:** October 22, 2016, 03:44:29 PM »

Should the piston "rattle" back and forth?

Quote from: Loose}{Cannon on October 22, 2016, 02:29:54 PM

Quote
Does anyone know if the piston should have .025 gap between the valve and the operating rod

Not sure what/where you are referencing here...
The length of the piston. It has a gap. In other words it seems short by .025. Will the new valve be longer or is it just wider?

Quote
the piston should drag from suction

Not a good test in my opinion, but a really corroded tube having too large of a diameter isnt ideal.

The new valve is over sized and will close up the gaps inside the gas block where it resides, and possibly the fitment to the tube. I would just wait and see how it acts with the new valve, and go from there.

Loose}{Cannon · « **Reply #8 on:** October 22, 2016, 03:57:49 PM »

Looks toast.... but still, see what the valve does.

SmittySKS · « **Reply #9 on:** October 22, 2016, 04:20:11 PM »

Should be here early next week. I'll keep ya posted.
But...if I do need to replace the GT, How much different is the Yugo from the others? I see a tube only for sale at Sarco. I really don't like the looks of the Tapco. Any way to retro fit the Tapco GT or one from another SKS? I don't see any Yugo GTs available. The guy I purchased the rifle from said he paid $100 for this one because when he got it, it had a tapco on it and he wanted it stock.. Claimed he never fired it.

firstchoice · « **Reply #10 on:** October 29, 2016, 04:22:20 AM »

Hey SmittySKS! How did the valve replacement go? Your original GT looks pretty rough. Judging from your other post, your Yugo isn't matching #'s, so look for a decent used replacement Yugo GT from ebay or other online parts outlet. The price shouldn't be too high. You're on the right track in keeping with original Yugo parts for a Yugo rifle. (up front disclaimer: I'm a purist, no hiding that.

) Many parts will interchange on the SKS, but a collector, or those dang purists, will see the difference. And, more often than not, you'll have better performance and reliability with original manufacturer parts.

Post some pics of your Yugo. We always like to see the pics! And welcome to the board!

firstchoice

SmittySKS · « **Reply #11 on:** October 29, 2016, 02:17:51 PM »

Was gonna wait till I get to the range again but this is what I've found so far.
With the new Murray valve and OEM GT, the gun cycles, but not well. It would stovepipe or just not eject the round. Which it didn't do before with the old valve. It just wouldn't cycle at all.
With the Tapco GT I couldn't get it to seat.The Murray valve is a bit longer. So I put the old GV back in. It looks like it had been changed already. No pitting but not SS like the Murray valve. So then the Tapco would seat but wouldn't latch. I swear it did when I tested the fitment at home!

Just took a few rounds (holding the GT down) to see if it would at least cycle. It wouldn't. Took the GT back out and noticed the piston would stick in the tube when clocked at different spots in the tube. Seemed there was a slight bend in the tube and a burr or something. Back in my shop I ran a rat tail file up the tube till the piston shaft ran free. Then found the high spot on the new GT and gently reworked the tube till the piston slid free. Thats where I'm at now. Waiting for an ammo shipment thats due next week before I go to the range for a test. Also, still looking for an answer to the piston length. I'm wondering if thats wrong.
Oh and I did get that paratrooper. Pics to follow. Looks to be in much better shape. All#matching but the stock doesn't have a # on it. Is that normal for paratrooper or is this a replacement stock?

Loose}{Cannon · « **Reply #12 on:** October 29, 2016, 07:01:44 PM »

I don't know what length your looking for...

SmittySKS · « **Reply #13 on:** October 30, 2016, 01:01:44 AM »

Quote from: Loose}{Cannon on October 29, 2016, 07:01:44 PM

I don't know what length your looking for...

The total length. How long is it and is it different then other SKS models.

Direct Connection · « **Reply #14 on:** October 31, 2016, 10:23:27 PM »

Sounds to me like your still leaking air/gas . Ive owned 1 59/66 and had the same problem but the Murrays valve fixed it. I would tear a piece of a white thin t-shirt and wrap it around the end where the gas tube meets with the valve and shoot it to see if your still getting leakage at the connection.. Should leave traces of powder or dirty air ect.. Good Luck

SmittySKS · « **Reply #15 on:** October 31, 2016, 10:58:52 PM »

Have a new GT coming from a guy in Croatia. He says its new. So we'll see.
Heres a few pics of my SKskenstein.

and one of my new paratrooper

Greasemonkey · « **Reply #16 on:** November 01, 2016, 10:37:28 PM »

Ok.. one thing I want to ask, because I see a new guy with a new to him SKS(no offence intended Smitty

), no one at all bought this question up at all in this "troubleshooting" and it's been eating me.. While the gas system is so easy to point at and fault.....this is one of those simple things can kick you in your bits.

Is the recoil spring installed correctly, is the squiggly end of the spring shoved in the carrier and not the straight side of the spring.

You have the right way and the wrong way it can be installed.

If it's installed backwards, it could short stroke when the spring binds up, imitating a leaking gas system, or making a slightly leaking gas system that works seem even worse.

Ya'll do what ya want... It's just a thought..

K.I.S.S. Keep It Simple Stupid

running-man · « **Reply #17 on:** November 01, 2016, 10:56:07 PM »

Leave it to GM to tell a guy that his fly is down...

He's right though, eliminate the easiest most obvious things first. If not the recoil spring, a good chamber cleaning with a 20 ga bore brush, some good solvent, and a drill motor is what I'd look at next before tossing parts at it.

Loose}{Cannon · « **Reply #18 on:** November 01, 2016, 11:51:49 PM »

ll good points. I tend to give benefit of the doubt that the return spring is in correctly. I woukd assume he does seing that a new valve made it mostly cycle.

Greasemonkey · « **Reply #19 on:** November 02, 2016, 12:14:56 AM »

I'm just going off no assumptions.. it's a simple, common, easy thing to overlook and everyone who has one, has done it at least once

There is no shame in it, it happens. I have bought them from individuals and shops and found them installed backwards. And if the new gas valve made it partially cycle, or short stroke, a backwards spring could be the final cause and remedy. A good chamber cleaning like RM suggested is always a good preventative measure as well.

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Author Topic: Yugo gas tube (Read 11845 times)