Trusting the Sniff Test...

[Mat H.]

Might be a chunk of bearing cage, worth a careful inspection speaking from experience a few years back

The roller bearings were all there. I meant to look at the damaged piston and got side-tracked making sure there wasn't any broken piston ring in the crankcase. Plus, I had limited time due to Trick or Treating with the little ones.

 

[Mat H.]

If it ran for 30 mins, you would have had oil in the mix!

Tank was 1/4 to half full before adding more fuel.

 

[lone wolf]

Doesn't look like damage from straight gas,
to me......

Over reved!

 

[Mat H.]

All back together. Questionable fuel drained. Missing chunk of piston ring found. Going to try and break Red in tomorrow.

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[grizz55chev]

All back together. Questionable fuel drained. Missing chunk of piston ring found. Going to try and break Red in tomorrow.

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Details!!

 

[Mat H.]

So, here is what I am thinking happen... The saw had between a 1/4 to 1/2 a tank of mix gas in it. I then added what I thought was mix gas, because I thought, for whatever reason, I could tell by sniffing the gas if it was mix. As it turned out, I was dreadfully incorrect. I think that since the mix was now more like 70:1 or 80:1 there was enough to slightly lubricate, but heat generated and the end of the ring played peak-a-boo with the exhaust port.

The only damage is from the ring on the piston and there is no sign of the piston scraping the cylinder wall, other than that gouge above the intake port.

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[HarleyT]

Nahhh.
Not fuel related....

 

[HarleyT]

Global warming maybe...

 

[sb47]

Thats why you should use a two stroke oil that is colored. I use stihl oil witch is blue and turns the gas a dark blue and I use only one can for mixed fuel and use the same can every time.
I bought a 12 pack of the stihl fuel mix in the single one gallon mix size and refill them from a bulk jug to save money. Again I use only one can for mixed fuel and only mix one gallon at a time and it's clearly dark blue in color so there is no mistaking it.

 

[Huskitoter]

The one gal prices have gotten ridiculous for H oil too - like three bucks a pop vs five for a five gal bottle. They can keep the small bottles.

 

[Bobby Kirbos]

Thats why you should use a two stroke oil that is colored. I use stihl oil witch is blue and turns the gas a dark blue and I use only one can for mixed fuel and use the same can every time.
I bought a 12 pack of the stihl fuel mix in the single one gallon mix size and refill them from a bulk jug to save money. Again I use only one can for mixed fuel and only mix one gallon at a time and it's clearly dark blue in color so there is no mistaking it.

Same here. I don't know if EVERY 2 stroke oil is dyed, but I don't remember ever seeing one that wasn't. To be totally honest, I never paid too much attention to it. Also, my mix is always in the same can and it is marked as such.

Hey, you live and learn. Sometimes you learn more from your mistakes than from your success. The real test is whether or not you actually DO learn from your mistakes....

 

[Ryan'smilling]

If there's a question about whether or not gas is mixed, you can slosh a little on some white paper. Straight gas will evaporate completely. Mixed gas will stain because of the oil.

 

[rogue60]

Forgot the oil/mix/gas/sniff thing as HarleyT and others have tried to say a few times this failure has nothing to do with the fuel mix.
The ring has clearly broken all on its own for whatever reason that was? a Friday ring maybe? or it has hung the ring in a port? it could have even been a crap port chamfer?.
Good or bad sniffing mix sensors has had nothing to do with this failure.

 

[grizz55chev]

So, here is what I am thinking happen... The saw had between a 1/4 to 1/2 a tank of mix gas in it. I then added what I thought was mix gas, because I thought, for whatever reason, I could tell by sniffing the gas if it was mix. As it turned out, I was dreadfully incorrect. I think that since the mix was now more like 70:1 or 80:1 there was enough to slightly lubricate, but heat generated and the end of the ring played peak-a-boo with the exhaust port.

The only damage is from the ring on the piston and there is no sign of the piston scraping the cylinder wall, other than that gouge above the intake port.

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What’s all back together, the one that broke the ring, or the one in the pic in post#44? New piston? New cylinder? Condition of the bearings in the lower end? Pics of reassembly?

 

[Mad Professor]

So, here is what I am thinking happen... The saw had between a 1/4 to 1/2 a tank of mix gas in it. I then added what I thought was mix gas, because I thought, for whatever reason, I could tell by sniffing the gas if it was mix. As it turned out, I was dreadfully incorrect. I think that since the mix was now more like 70:1 or 80:1 there was enough to slightly lubricate, but heat generated and the end of the ring played peak-a-boo with the exhaust port.

The only damage is from the ring on the piston and there is no sign of the piston scraping the cylinder wall, other than that gouge above the intake port.

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Ring broke on intake side near the pin.

Unless piston was in backwards.............

Edit: pic on post #1 has piston installed correctly. What does intake port look like?

 

[Mad Professor]

We were always taught the scratch and sniff test.

 

[Mat H.]

Not sure if you can see the smoke, but RED LIVES!

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[Bobby Kirbos]

Not sure if you can see the smoke, but RED LIVES!

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Nice!

 

[HarleyT]

She can see it!!

 

[burnses]

nice job getting it back together....on original picture I can see a shadow on the rings where it looks like note really fitting the bore to well. Also possibly the ring bottoming in the ring groove "back clearance" could be ring end gap butted together and ring edge jammed on the port breaking the ring.....Looks mechanical and just happened to happen when ya had unmixed fuel.....youll find out soon enough.. Two ring piston could have broke the ring in install and it just broke at a later time...

good luck
the can