Seized chainsaw
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MossRoad
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Piston got more than 1/4" long deep scratch.
MossRoad
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Brightened it up a bit.
Dmacleo
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wow.
who amongst us has never killed a 2 stroke?
be honest, I'll admit to the deaths I've caused.
but that...wow.
my hat is off to you
I kid
who amongst us has never killed a 2 stroke?
be honest, I'll admit to the deaths I've caused.
but that...wow.
my hat is off to you
I kid
BnRidge
Platinum Member
Ok, what the happened. You don't fry something like that without a clue.
RandyT
Elite Member
OP claims straight gas, but that piston looks more like it ate something that it didn't like.
IrishLoader
Silver Member
Maybe part of the ring? Ethenol poisoning will eat up a saw pretty quick. One of the most common terms I have heard right before grenading was, "It was running great!"
For the average home/farm owner I would always try to recommend the various canned versions of ethanol free fuel that was pre mixed. For the record all my small stuff right up to the 18 hp orange motorized goat for trimming the grass gets treated fuel ether pre mix for the 2 strokers and the 4 strokers get Stabil 360. Saves a lot of headaches and "seasons" the various carbs with "clean" fuel and mix/stabilizer.
dodge man
Super Star Member
That’s bad, definitely needs a new piston and cylinder.
MossRoad
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OP never claimed straight gas.
gstrom99
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OUCH. That's one tore up piston! The local Casey's sells non-ethanol gas also. Even though Husq says it can use "up to" 10% ethanol, I always buy the straight stuff, before mixing in oil and stabilizer, for my 2 stroke tools. I have plenty of gas cans around here - I just wish they came with decent (old style) spouts. The pre-mixed stuff is a good, but pricey, option too.
ericm979
Super Member
That's quite a seizure.
Can we get a pic of the piston crown from the top, and from underneath (the inside of the piston, focused on the underside of the crown)? From the one pic it looks like it overheated, maybe caused by detonation. The missing piece of piston was melted away. That's likely detonation. By then the ring was already stuck in the groove and wasn't sealing. Once the piston melted the ring broke. The damage on the skirt is from lack of lubrication.
It's hard to say if the overheating was caused by detonation or caused it, and if the lack of lube on the skirt contributed to overheating or was caused by it.
Based on this I'd be wanting to check that there wasn't something causing it to run lean and hot, like an air leak or fuel blockage or a really bad carburetor setting.
Can we get a pic of the piston crown from the top, and from underneath (the inside of the piston, focused on the underside of the crown)? From the one pic it looks like it overheated, maybe caused by detonation. The missing piece of piston was melted away. That's likely detonation. By then the ring was already stuck in the groove and wasn't sealing. Once the piston melted the ring broke. The damage on the skirt is from lack of lubrication.
It's hard to say if the overheating was caused by detonation or caused it, and if the lack of lube on the skirt contributed to overheating or was caused by it.
Based on this I'd be wanting to check that there wasn't something causing it to run lean and hot, like an air leak or fuel blockage or a really bad carburetor setting.
Snobdds
Super Member
Correct. That honor lies on me.
RandyT
Elite Member
I mistook the post number 2 for the OP which was a mistake
RandyT
Elite Member
I am assuming that is the exhaust port in the cylinder in the picture and not the intake port. The problem is either that is the intake port and the saw ingested a foreign object or the piston was installed backwards at the factory. That piston damage is were the anti-rotation pin would be located which should be installed toward the intake port and would set between the intake port and the transfer port in the cylinder.
MossRoad
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I'd guess the port you can see on the bottom of the picture is the intake port. The exhaust should have the studs on it facing towards the top of the picture. You can't see the exhaust port in that picture.
RandyT
Elite Member
Would be nice to also see the exhaust port to see which side the problem started on. Did the exhaust score first and the limited space drive the piston into the intake side of the cylinder or did the engine eat something and jammed between the piston and cylinder wall causing that damaged area on the piston.
MossRoad
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Here's a pretty good video that shows several causes of scoring. The examples he shows all lean towards raw gas (no or not enough oil). Intake side is scored heavily. I'd like to see the other side of the piston.
Interestingly, around 11:00 he talks about the cold seizure we talked about earlier. Not warming the engine before going full throttle. Not the cause in this case, but a cause of piston scoring nonetheless.
Interestingly, around 11:00 he talks about the cold seizure we talked about earlier. Not warming the engine before going full throttle. Not the cause in this case, but a cause of piston scoring nonetheless.
MossRoad
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I'm guessing he showed us the major damage side. Intake side of the piston and intake side of the cylinder. I'm sticking with raw gas, not enough oil in the mix, or some catastrophic debris injection.
But yes, it would be fun and educational to see the other sides.
Here are some similar links:
