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Busted a ring this morning ??

redline4

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Maybe the ring was put in upside down causing it to expand and snap? Just thinking outloud. Glad it didnt do to much damage.
Cool trick there Ed.

Thanks Jeff.
It doesnt stress the ring like using expanders or simply prying it open and over the o.d. of the piston.
If you have an old piston laying around, give it a try. It's super easy to remove or install.
 

RI Chevy

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I broke the last ring I took off. I will try this trick next time. [emoji106]
 

Wonkydonkey

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Does this gooder way of installing rings work with a two ring piston, or is there another way
Edit: I just inlarged the vid I now see it is a 2 ringed piston :facepalm:
And do you do the bottom ring the same way :eusa_whistle: just asking to be sure..

Btw that vid sure made it look cool and easy. Cheers redline4
 
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redline4

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@Wonkydonkey yes, it works on any 1 or 2 ring piston.
I work at a GM dealer, so Im doing large 4 stroke pistons, but I install the oil ring, which is a 3 piece ring and both compression rings on them this same way.

The further down from the crown the ring land is, one just needs to move slower. The closer to the crown, the easier it is.
 

Al Smith

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The last time I used a ring expander on anything was over 50 years ago and I broke a ring on a 1938 Allis Chalmers model B engine .I use nothing but my fingers on anything from tiny little chainsaw piston rings to over 5" rings for diesels .I don't even use a ring compressor on chainsaw pistons ,haven't broken one yet .
 

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Thanks everyone, I appreciate you all. I’ll come back after I’ve successfully repaired the saw. Who said 2-strokes were simple? LOL

Are you still waiting on parts?

Or what was the resolve to that busted ring?
 

av8or3

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Are you still waiting on parts?

Or what was the resolve to that busted ring?
No, I got parts, and more parts. I cleaned up the cyl and it looked useable and installed another new Meteor piston. I did check the ring end gap and filed them for the .008 gap. Less than 1/2 tank of fuel and the very same failure occurred again. Ruined piston and another chunk missing from the exhaust port. This time I threw out both the cyl and the piston and replaced them with a new OEM kit I recently acquired. Press/vac tested on reassembly successfully and away we go. I’m now into the 4th tank and the saw has settled down into normal behavior.
I’m not sure exactly why I was having that problem. When I bought the refurbished OEM cylinder I was surprised to find the exhaust port beveled quite a bit. In the cyl’s I’ve cleaned up, all that was necessary was Scotchbrite and Purple Morado (caustic soap) used to attack the aluminum transfer. I’ve never had to grind on anything. I can’t say for sure why the pistons failed, but after two, I’m not risking a third.
The failures mimic that which occurs when overspeeding the engine according to a very informative Madsen site diagnosing piston damage. But I’m certain that wasn’t the case here. Don’t know what happened, but OEM stuff appears to have fixed it , so far. Although this saw was built for a friend, I’ll be keeping this one for a while and using it, rather than risk a failure with him. Appreciate all the interest and suggestions.
 

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Thanks for the update, if I don’t learn something new everyday I must have died!

That’s a very strange problem right there, since it repeated itself.

I have reworked only one cylinder that someone literally put a square shanked screwdriver into the exhaust port to act as a piston stop to remove the clutch, but it ran fine afterwards.

Quite a bit of the exhaust port top was removed, reshaped, & re-chamfering was required to get that “dent” out, lol.

Good that you’ve got it running again.
 

BuckthornBonnie

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@av8or3 what do you mean by stretching the rings?

I put on hundreds of them a year. I always roll them on. I made a quick vid to demonstrate.


That way has never failed me or broken a ring.

I remove them the same way, just reverse motion.
At the end where you adjusted the ring in its groove... does it ever scratch the piston when you settle it in? New rings, especially.

Nice technique, though.
 

BuckthornBonnie

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No, I got parts, and more parts. I cleaned up the cyl and it looked useable and installed another new Meteor piston. I did check the ring end gap and filed them for the .008 gap. Less than 1/2 tank of fuel and the very same failure occurred again. Ruined piston and another chunk missing from the exhaust port. This time I threw out both the cyl and the piston and replaced them with a new OEM kit I recently acquired. Press/vac tested on reassembly successfully and away we go. I’m now into the 4th tank and the saw has settled down into normal behavior.
I’m not sure exactly why I was having that problem. When I bought the refurbished OEM cylinder I was surprised to find the exhaust port beveled quite a bit. In the cyl’s I’ve cleaned up, all that was necessary was Scotchbrite and Purple Morado (caustic soap) used to attack the aluminum transfer. I’ve never had to grind on anything. I can’t say for sure why the pistons failed, but after two, I’m not risking a third.
The failures mimic that which occurs when overspeeding the engine according to a very informative Madsen site diagnosing piston damage. But I’m certain that wasn’t the case here. Don’t know what happened, but OEM stuff appears to have fixed it , so far. Although this saw was built for a friend, I’ll be keeping this one for a while and using it, rather than risk a failure with him. Appreciate all the interest and suggestions.
Interested in finding out the why, too. If your new top end goes, check the crank, bearings, and case area. It’s unlikely to be any of those, though.

If that was an eBay refurb, I bet the guy does a bunch of cleanups using dremels and the like. It’s possible that it’s out of round or the port shape has been drastically changed. Dumb question- but everything was the correct size, right? Bore, rings, piston?
 

redline4

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At the end where you adjusted the ring in its groove... does it ever scratch the piston when you settle it in? New rings, especially.

Nice technique, though.


If you just jam it down, yes you could, but I keep a small amount of pressure on it with my finger to keep it off the side of the piston.

1.4L pistons I just did Friday.
20190613_161621.jpg
 

cuinrearview

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Interested in finding out the why, too. If your new top end goes, check the crank, bearings, and case area. It’s unlikely to be any of those, though.

If that was an eBay refurb, I bet the guy does a bunch of cleanups using dremels and the like. It’s possible that it’s out of round or the port shape has been drastically changed. Dumb question- but everything was the correct size, right? Bore, rings, piston?
If this is the jug @av8or3 got from me it came from a running red lever saw. It had some slight transfer but no scratches. The cleanup with 240 and 500 grit was easy, the same as others that I have done and used. No changes were made to the port shape and no work was done to the bevels. It was as it came from the factory. I was never contacted, but if I was and the cylinder was suspected I would have bought it back to diagnose.
 

BuckthornBonnie

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If this is the jug @av8or3 got from me it came from a running red lever saw. It had some slight transfer but no scratches. The cleanup with 240 and 500 grit was easy, the same as others that I have done and used. No changes were made to the port shape and no work was done to the bevels. It was as it came from the factory. I was never contacted, but if I was and the cylinder was suspected I would have bought it back to diagnose.

Nice. Something else was wrong, then.
 
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